The Best Period Tracker for Irregular Periods in 2026
We compared 8 period trackers on how they handle cycles that change length, from honest date ranges to ovulation tests, next to what doctors call irregular.
9 min read
How we review
Period Tracker Apps is run by the team that makes Hello Phase, the app ranked first on this list. We checked every app against its store listings, pricing, privacy label, help pages and recent reviews that mention irregular cycles on 26 October 2026, without hands-on testing of each one, and medical facts come from the Office on Women's Health, ACOG and FIGO. There are no affiliate links, and our review method explains how we rank our own app.
Our pick
Hello Phase Our app
Best for irregular periods on Android- Shows your next period as a range that widens when your cycles vary
- Says how many cycles it learned from and how close each forecast was
- Needs no account, with a free CSV and PDF summary for your doctor
Quick answer. Hello Phase is the best period tracker for irregular periods on Android because it shows your next period as a date range that gets wider when your recent cycles vary more, says how many cycles it has learned from, tells you after each period how close the forecast was and lets you pause predictions when something changes, all free and without an account. drip is the free open source option that also shows a range. On iPhone, Apple Health's free Cycle Tracking can flag irregular cycles from six months of logs, and if you need to know when you actually ovulate, a temperature or hormone method such as Natural Cycles or Inito measures it instead of counting days.
Top picks at a glance
- 1Hello PhaseBest for irregular periods on Android
- 2
drip period & cycle trackerFree, shows predictions as a range - 3
Clue Period & Cycle TrackerLets you hide unusual cycles - 4Apple Health Cycle TrackingFree irregular cycle alerts on iPhone
- 5
FloA large app with a doctor report - 6
Natural CyclesConfirms ovulation with temperature - 7
Premom Ovulation TrackerReads ovulation test strips - 8
Inito Fertility MonitorMeasures four hormones at home
What counts as an irregular period?
There is no single number, and the official sources do not agree. The US Office on Women's Health says a normal cycle lasts 24 to 38 days and that periods can be irregular if your cycle length varies by more than 20 days from month to month. ACOG puts normal at 21 to 35 days and counts cycles that vary by more than 7 to 9 days as irregular, and FIGO, the international federation of gynecologists, allows up to 9 days of variation at ages 18 to 25 and 42 to 45, and up to 7 days at ages 26 to 41.
| Source | Typical cycle | Called irregular when |
|---|---|---|
| Office on Women's Health (US HHS) | 24 to 38 days | Cycle length varies by more than 20 days from month to month |
| ACOG | 21 to 35 days | Cycle length varies by more than 7 to 9 days |
| FIGO | 24 to 38 days | Variation over 9 days at ages 18 to 25 and 42 to 45, over 7 days at ages 26 to 41 |
| Apple Health Cycle Tracking | Not stated | Cycle lengths vary by 17 days or more in two back-to-back 90-day windows |
Uneven cycles are expected in the first years after your first period, and ACOG's guide for teens says cycles of 21 to 45 days are normal and that it may take 6 years or more for your cycle to get regular. They are also common in perimenopause. The Office on Women's Health lists thyroid problems, long-term stress, gaining or losing a lot of weight, breastfeeding and PCOS among the causes, and says about 1 in 10 women with irregular menstrual cycles has PCOS, while Cleveland Clinic notes that periods can be irregular for up to six months after you stop the pill.
When should you see a doctor about irregular periods?
The Office on Women's Health says to call your doctor or nurse if any of these happen.
- Your periods become irregular after having been regular.
- Your period comes more often than every 24 days or less often than every 38 days.
- Your period lasts longer than eight days.
- You have gone three months without a period and are not pregnant or breastfeeding.
Hello Phase gives similar advice inside the app, using the 21 and 35 day limits that ACOG uses, and none of the apps on this page can tell you why your cycles are irregular.
Can a period app predict irregular periods?
Less well, and the research says so. A 2021 study of Clue data found that more variable users are "generally more difficult to predict", and in a small 2025 study of a Huawei wristband, with Huawei authors, its period predictions were right 75.0% of the time for regular cycles and 50.8% for irregular ones. A 2026 review of the store descriptions of 10 popular period trackers found that none warned that their predictions may be inaccurate.
We found no independent study from 2023 to 2026 that compares named apps for irregular cycles, so the useful test is whether an app shows you its uncertainty, lets you set an unusual cycle aside, or measures ovulation instead of counting days.
Honest predictions
Ranges, or set odd cycles aside
- Hello Phase
- drip
- Clue
Alerts or a doctor report
Flags patterns, exports a summary
- Apple Health
- Flo
Know when you ovulate
Temperature or hormone tests
- Natural Cycles
- Premom
- Inito
Think you might have PCOS? Our guide to the best PCOS apps covers what to log for your doctor.
How we picked the apps
We looked for features built for uneven cycles, such as a date range instead of one confident day, a way to set an unusual cycle aside, alerts for irregular patterns and ways to confirm ovulation, then checked each app's store listing, US price, privacy label and recent reviews that mention irregular cycles. Hello Phase ranks first on Android for showing its uncertainty openly without an account, drip ranks second as the free open source option that also shows a range, and Apple Health is our free pick on iPhone.
Side by side
| App | Best for | How it handles uneven cycles | Ovulation from | Price per year (US) | Platforms |
|---|---|---|---|---|---|
| Hello Phase | Best on Android, no account | Range of 1 to 7 days either side from your last six cycles, shows cycles learned and how close each forecast was | Calendar estimate | $39.99 for optional Plus | Android |
| drip period & cycle tracker | Free and open source | Marks extra possible start days when cycles vary, skips cycles over 99 days | Temperature and cervical mucus you log | $0 | iPhone, Android |
| Clue Period & Cycle Tracker | Setting odd cycles aside | Lets you hide a cycle from predictions, says it needs more data when cycles are irregular | Calendar estimate | $39.99 for Clue Plus | iPhone, Android |
| Apple Health Cycle Tracking | Free alerts on iPhone | Flags irregular, infrequent or prolonged periods from six months of logs | Calendar, or wrist temperature on Apple Watch Series 8 or later | $0 | iPhone, Apple Watch |
| Flo | A large app with a doctor report | Widens the fertile window to about 14 days when unsure | LH test results and temperature you log | Not labeled, $1.99 to $59.99 listed | iPhone, Android |
| Natural Cycles | Confirming ovulation, birth control | Says effectiveness is not affected, with more Red Days | Temperature from its band or a wearable | $149.99 | iPhone, Android |
| Premom Ovulation Tracker | Reading LH test strips | Calendar adjusts from your test and temperature data | LH strips scanned with your camera | Not labeled, $20.49 to $37.99 listed | iPhone, Android |
| Inito Fertility Monitor | Hormone numbers at home | Number of tests depends on your cycle length | Estrogen, LH, PdG and FSH in urine | $119 monitor with a code, $49 for 15 strips | iPhone, Android |
If you want predictions that admit uncertainty
A single confident date is the wrong answer when your cycles move around. These three apps either show a range that reflects how much your cycles vary or let you keep one odd cycle from skewing the next forecast.
Hello Phase
Best for irregular periods on Android- $39.99 for optional Plus
- Android
- No Play rating yet, 1K+ installs
- Privacy declaration
- Play "No data shared", some data collected
What stands out
- Hello Phase is our app, and it shows your next period as a date range instead of a single day. The range is set by how much your last six cycles varied, from a day either side when they are steady to a week either side when they swing, and a line under the forecast says how many cycles it has learned from.
- Each new cycle counts a little more than older ones, so the forecast follows real changes without jumping at one unusual month, and after every period it tells you the date it expected and the date your period came.
- When a period is late, the calendar says by how many days, and Something changed lets you pause predictions for a pregnancy, a recent birth, a pregnancy loss or another reason while your logs stay saved. The free plan covers your next three periods, and you can export every logged day as a CSV file or a one-page PDF summary of your cycle lengths.
Watch out for
- It is Android only, and with 1K+ installs it has no Google Play rating yet.
- Predicted cycles are kept between 21 and 45 days and gaps over 90 days are left out, so very long cycles will be forecast early. Its fertile window is a calendar estimate, because it does not read ovulation tests or temperature.
See the pricing page and the Hello Phase FAQ. The 12-month forecast is part of Plus.
Get it onGoogle Play
Price, account and privacy details
- Best for
- Irregular periods on Android, with date ranges sized by how much your cycles vary, cycles learned, a check after each period and a pause for life changes, all without an account
- Price (US, checked 26 Oct 2026)
- Free for tracking and your next three periods. Plus is $39.99 a year or $12.99 a month on Google Play and adds the 12-month forecast.
- Platforms
- Android. There is no iPhone version yet.
- Account
- None, with no sign up and no login
- Predictions
- The next start date plus or minus 1, 3, 5 or 7 days, based on the spread of your last six cycles. Cycle lengths from 15 to 90 days are counted, and predictions stay between 21 and 45 days.
- Privacy
- No ads and no third-party trackers. Google Play Data safety says no data is shared with third parties and lists some data types as collected.
- Ratings
- No Google Play rating yet, 1K+ installs, updated Oct 1, 2026
drip period & cycle tracker
Free, shows predictions as a range- Free
- iPhone, Android
- 4.02 (59) App Store
- 4.2 (470) Google Play
- Privacy declaration
- Apple "Data Not Collected", Play "No data collected"
What stands out
- After three complete cycles drip predicts your next three period starts, and when your cycle lengths vary more it marks four possible extra days around each one instead of two, so the calendar shows its uncertainty.
- It will not guess your fertile days from bleeding alone, is free with no account, and both stores show it declaring no data collected.
Watch out for
- drip skips cycles longer than 99 days, and a 2026 App Store reviewer wrote "i really wish it let me track cycles longer than 100 days".
On the App Store and Google Play, and the drip FAQ.
Price, account and privacy details
- Best for
- A free, open source tracker that shows predictions as a range
- Price (US, checked 26 Oct 2026)
- Free, with no in-app purchases on either store
- Platforms
- iPhone and Android
- Account
- None
- Privacy
- Apple label "Data Not Collected". Google Play Data safety says no data is collected or shared.
- Ratings
- 4.02 (59 US ratings) on the App Store, 4.2 (470 reviews) on Google Play
Clue Period & Cycle Tracker
Lets you hide unusual cycles- $39.99 for Clue Plus
- iPhone, Android
- 4.76 (406,487) App Store
- 4.5 (1.5M) Google Play
- Privacy declaration
- Apple "Data Used to Track You", Play lists some data shared
What stands out
- Clue lets you hide specific cycles so they do not throw off your future predictions, which helps after one very long or very short cycle, and its Analysis tab shows how much your cycles vary.
- Clue says its algorithm needs 3 past cycles for its core predictions, and that with irregular cycles it may need more cycle data before becoming precise.
Watch out for
- You need an account, and in our Clue alternatives guide half of the recent low-star US reviews complained about Clue Plus pop-ups. One reviewer in August 2026 wrote "clue continues to assume I'll, what, magically stop being irregular or having short cycles?"
On the App Store and Google Play.
Price, account and privacy details
- Best for
- Hiding an unusual cycle so it does not skew predictions, on both phones
- Price (US, checked 26 Oct 2026)
- Free plan. Clue Plus is $39.99 a year or $9.99 a month in the App Store.
- Platforms
- iPhone and Android
- Account
- Required for new users since 2019, with data kept on servers in the EU
- Privacy
- Apple label "Data Used to Track You" for identifiers. Google Play Data safety lists some data shared, including device IDs for advertising or marketing.
- Ratings
- 4.76 (406,487 US ratings) on the App Store, 4.5 (1.5M reviews) on Google Play, updated Oct 21, 2026
If you want an alert or a report for your doctor
Both apps below can turn months of logs into something to show a doctor, and Apple Health will also tell you when your pattern looks irregular.
Apple Health Cycle Tracking
Free irregular cycle alerts on iPhone- Free
- iPhone, Apple Watch
- Built in, no store rating
- Privacy declaration
- Encrypted on a locked iPhone, end-to-end iCloud backup with two-factor authentication
What stands out
- Cycle Tracking can tell you if six months of logs show irregular cycles, infrequent periods, prolonged periods or persistent spotting, and the Apple Women's Health Study describes the irregular alert as cycle lengths that vary by 17 days or more.
- You can export the last 12 months of your cycle history as a PDF to share with your healthcare provider.
Watch out for
- The fertile window is a calendar estimate, alerts switch off while you have a cycle factor such as pregnancy logged, and it works only on iPhone.
See Apple's Cycle Tracking guide.
Price, account and privacy details
- Best for
- Free alerts for irregular cycles on iPhone, with a 12-month PDF for your doctor
- Price (US, checked 26 Oct 2026)
- Free, built into the Health app
- Platforms
- iPhone and Apple Watch. Wrist temperature needs Apple Watch Series 8 or later, or any Ultra.
- Account
- Your Apple ID only
- Privacy
- Health data is encrypted when your iPhone is locked. With iOS 12 or later and two-factor authentication, Apple says it cannot read the Health data in your iCloud backup.
- Ratings
- Built in, so there are no store ratings
Flo
A large app with a doctor report- Not labeled, $1.99 to $59.99 listed
- iPhone, Android
- 4.74 (2,005,621) App Store
- 4.7 (5.16M) Google Play
- Privacy declaration
- Apple "Data Used to Track You", Play "No data shared"
What stands out
- Flo lets you log LH test results and basal body temperature, offers cycle report summaries you can download and share with your doctor, and says that when it cannot predict your cycle length well it widens your fertile window to around 14 days.
Watch out for
- A Google Play reviewer wrote in July 2026 that "It will not recognize cycles shorter than 21 days", and in June 2021 the FTC finalized an order over allegations that Flo shared health data with Facebook and Google.
On the App Store and Google Play, and how Flo describes its accuracy.
Price, account and privacy details
- Best for
- A large app with LH and temperature logging and a cycle report for your doctor
- Price (US, checked 26 Oct 2026)
- Free plan. The App Store lists Flo Premium at five prices from $1.99 to $59.99 without saying how long each one lasts.
- Platforms
- iPhone and Android
- Account
- Sign-in, with Anonymous Mode
- Privacy
- Apple label "Data Used to Track You" for purchases, location, identifiers and usage data. Google Play Data safety says no data is shared.
- Ratings
- 4.74 (2,005,621 US ratings) on the App Store, 4.7 (5.16M reviews) on Google Play
If you need to know when you ovulate
Calendar apps count back from your next expected period, which is the part irregular cycles break. A 2018 study by the maker of Clearblue tests found that apps predicted the day of ovulation no better than 21% of the time, so if timing matters for getting pregnant or for birth control, the three apps below measure a body signal instead.
Natural Cycles
Confirms ovulation with temperature- $149.99
- iPhone, Android
- 4.79 (30,293) App Store
- 4.4 (23.5K) Google Play
- Privacy declaration
- Apple "Data Used to Track You", Play "No data shared"
What stands out
- Natural Cycles uses your temperature from its own NC° Band or a wearable such as Apple Watch or Oura Ring to detect ovulation instead of assuming it, it is FDA cleared as birth control, and its help center says "Yes, you can use Natural Cycles if you have irregular cycles."
- It says its effectiveness as birth control is not affected by irregular cycles, and suggests adding ovulation tests to narrow down your fertile days.
Watch out for
- Irregular cycles bring more Red Days, when it tells you to use protection, and a Google Play reviewer wrote "If you have an even slightly irregular period you will have so many red days it's useless." It is also the most expensive app here.
On the App Store and Google Play, and Natural Cycles on irregular cycles.
Price, account and privacy details
- Best for
- Confirming ovulation with temperature, and FDA-cleared birth control
- Price (US, checked 26 Oct 2026)
- Annual $149.99 or Monthly $21.99 in the App Store
- Platforms
- iPhone and Android
- Account
- Required. A Go Anonymous option separates your identity from your fertility data.
- Privacy
- Apple label "Data Used to Track You" for contact info. Google Play Data safety says no data is shared.
- Ratings
- 4.79 (30,293 US ratings) on the App Store, 4.4 (23.5K reviews) on Google Play, updated Oct 15, 2026
Premom Ovulation Tracker
Reads ovulation test strips- Not labeled, $20.49 to $37.99 listed
- iPhone, Android
- 4.78 (60,635) App Store
- 4.3 (38.7K) Google Play
- Privacy declaration
- Apple no tracking, Play lists data shared, including location and device IDs
What stands out
- Premom scans your ovulation test strips with your phone camera and puts a number on your LH level, and it says its period calendar "adjusts based on your ovulation test and BBT data" rather than on dates alone.
Watch out for
- It needs an account, Google Play reviewers in September 2026 said their past cycles now sit behind the paywall, and in May 2023 the FTC announced a proposed order barring Premom from sharing health data for advertising.
On the App Store and Google Play.
Price, account and privacy details
- Best for
- Reading and logging LH test strips when your ovulation day moves around
- Price (US, checked 26 Oct 2026)
- Free to download. The App Store lists Premium at $20.49 to $37.99 without billing periods.
- Platforms
- iPhone and Android
- Account
- Required
- Privacy
- Apple label shows no tracking and lists health, location and identifiers as linked to you. Google Play Data safety lists data shared, including app activity, location and device IDs.
- Ratings
- 4.78 (60,635 US ratings) on the App Store, 4.3 (38.7K reviews) on Google Play, updated Oct 22, 2026
Inito Fertility Monitor
Measures four hormones at home- $119 monitor with a code, strips extra
- iPhone, Android
- 4.94 (5,302) App Store
- 4.7 (108) Google Play
- Privacy declaration
- Apple links contact info only, Play "No data shared"
What stands out
- Inito reads estrogen, LH, PdG and FSH from one urine strip and confirms whether you ovulated, and its FAQ says it gives "actual urinary hormone values" even with irregular cycles. The app itself is free.
Watch out for
- Inito says someone with a 30-day cycle may need 12 to 15 tests, so long cycles use more strips, or as one App Store reviewer put it, "those who have 40-50 days long cycles I feel for your wallet".
On the App Store and Google Play, and Inito FAQs.
Price, account and privacy details
- Best for
- Measuring hormone levels at home when your ovulation day is hard to pin down
- Price (US, checked 26 Oct 2026)
- The monitor with 15 strips is $169, or $119 with a code shown in Inito's shop, and more strips are $49 for 15. The app is free.
- Platforms
- iPhone and Android. Inito says the monitor is sold in the US only.
- Account
- Not stated
- Privacy
- Apple label lists contact info as linked to you. Google Play Data safety says no data is shared or collected.
- Ratings
- 4.94 (5,302 US ratings) on the App Store, 4.7 (108 reviews) on Google Play
Find the right app for you
What should you log before a doctor visit?
ACOG suggests keeping track for several weeks before your visit, noting the dates, length and type of your bleeding, whether light, medium, heavy or spotting, and says a smartphone app designed to track menstrual cycles works for this. Hello Phase logs flow as none, spotting, light, medium or heavy each day, and its free one-page PDF summary lists each cycle's start date, cycle length and period length.
Apps we left out and why
Ovia says it supports irregular cycles, but its reviews that mention irregular cycles had more one-star ratings than any other app we checked, and several said it fills in a predicted period by itself. A Glow reviewer said temperature could only come from a Glow thermometer, Stardust makes no claim about irregular cycles and Mozilla's 2026 study found it shared health data with an analytics firm, and Period Calendar Period Tracker is free on Android but lists no feature for irregular cycles beyond saying it works for them.
How to choose
On Android, start with Hello Phase if you want a forecast that tells you how sure it is, or drip if open source code matters most. On iPhone, turn on Apple Health's cycle deviation alerts. If you are trying to get pregnant or need birth control, a single date from any calendar app is not enough, so look at Natural Cycles, Premom or Inito, and if your cycles are often longer than 35 days, our guide to the best PCOS apps explains what to bring to your doctor.
Questions people ask
What is the best period tracker for irregular periods?
On Android, Hello Phase is the best period tracker for irregular periods, because it shows your next period as a date range sized by how much your cycles vary, says how many cycles it learned from and tells you how close each forecast was, for free and without an account. drip is a free open source option that also shows a range, Apple Health is the free pick on iPhone, and Natural Cycles or Inito measure ovulation directly.
What counts as an irregular period?
It depends on the source. The Office on Women's Health says a normal cycle is 24 to 38 days and that cycles varying by more than 20 days from month to month are irregular, while ACOG uses 21 to 35 days and counts variation of more than 7 to 9 days as irregular.
Can a period app predict irregular periods?
Only roughly. Research on Clue data found that people with more variable cycles are harder to predict, and in a small 2025 wristband study, period predictions were right 50.8% of the time for irregular cycles against 75.0% for regular ones. Look for an app that shows a range and says how many cycles it learned from.
When should I see a doctor about irregular periods?
The Office on Women's Health says to see a doctor or nurse if your periods become irregular after being regular, come more often than every 24 days or less often than every 38 days, last longer than eight days, or stop for three months when you are not pregnant or breastfeeding.
What is the best app for irregular periods on iPhone?
Apple Health's built-in Cycle Tracking is free and can alert you when six months of logs show irregular, infrequent or prolonged periods. drip, Clue, Flo, Natural Cycles, Premom and Inito are also on iPhone, while Hello Phase is Android only for now.
Can I use a period app as birth control if my cycles are irregular?
Only an app cleared for that use. Natural Cycles is FDA cleared as birth control and says irregular cycles do not change its effectiveness, although you will get more Red Days. The other apps here, including Hello Phase, give estimates that should not be used to prevent pregnancy.
Can irregular periods be a sign of PCOS?
They can. The Office on Women's Health says about 1 in 10 women with irregular menstrual cycles has PCOS, and the 2023 international PCOS guideline says a diagnosis of PCOS should be considered when irregular cycles are present, so talk to a doctor rather than relying on an app.
Try Hello Phase
Hello Phase is free on Android with no account, no ads and no third-party trackers, and it shows your next period as an honest date range that narrows as it learns your cycles.
Get it onGoogle PlayReferences
Store listings for every app are linked from its card above and were checked on 26 October 2026.
- Office on Women's Health, Your menstrual cycle
- Office on Women's Health, Period problems
- ACOG, Abnormal uterine bleeding
- ACOG, Your first period
- Jain V et al. 2023, FIGO systems for abnormal uterine bleeding, Int J Gynaecol Obstet
- Teede HJ et al. 2023, international PCOS guideline, J Clin Endocrinol Metab
- Cleveland Clinic, abnormal menstruation
- Li K et al. 2021, cycle variability and prediction accuracy in Clue data, J Am Med Inform Assoc
- Luo C et al. 2025, wristband menstrual prediction in regular and irregular cycles, Reprod Biomed Online
- Graham A et al. 2026, store descriptions of popular period tracker apps, Hum Fertil
- Johnson S et al. 2018, accuracy of ovulation prediction by apps, Curr Med Res Opin
- Zhang S et al. 2023, Apple Women's Health Study menstrual patterns, Am J Obstet Gynecol
- Apple Support, Cycle Tracking
- Apple Platform Security, protecting access to Health data
- Clue help, how Clue predictions work
- Clue help, hiding cycles
- drip FAQ, predictions
- Flo, accuracy of predictions
- FTC, order finalized with Flo Health, June 2021
- Natural Cycles help, using Natural Cycles with irregular cycles
- FDA, De Novo DEN170052 decision summary, Natural Cycles
- Natural Cycles help, What is Go Anonymous
- FTC, proposed order against Premom, May 2023
- Inito FAQs
- Inito, monitor and strip prices
- TechCrunch, Stardust shares health data with analytics firm, July 2026
- Hormone Tracker - Hello Phase on Google Play
- Hello Phase privacy policy
History of updates
- , first published
Hello Phase is for tracking and learning about your cycle. It is not a contraceptive and it does not diagnose medical conditions. Nothing on this page is medical advice.
