Disclosure first, because it matters: this is the blog of Ebb, a period tracker we built specifically for irregular cycles. You should read everything below knowing that, and we've written it so that it stays useful even if you end up choosing someone else's app. Several of the apps here are genuinely good; we'll say so plainly.
Now, the actual problem. If your cycles vary (26 days, then 38, then 31), most period trackers fail you in the same specific way: they predict a single confident date by averaging your history, your body ignores the average, and the app spends half the month telling you you're "late." So the question isn't "which tracker has the most features." It's: which trackers are honest about uncertainty, and which just decorate a guess?
Here's how the field actually looks, judged on three things that matter for irregular cycles: prediction honesty · irregular/PCOS awareness · data privacy.
The short version
| App | Prediction approach | Best for |
|---|---|---|
| Ebb (ours) | Range + confidence level, built for irregularity; on-device | Irregular/PCOS cycles wanting honest predictions + privacy |
| Bearable | Deliberately makes no predictions | Symptom-pattern tracking without prediction theater |
| Clue | Single-date predictions, science-forward brand, flags irregularity | Mainstream tracking with good education content |
| Drip / Euki | Basic or no predictions; fully on-device, open source | Maximum-privacy minimalists |
| Flo | Single-date predictions, huge feature set | Feature breadth; less suited to prediction honesty |
| MyFlo / Ovia and similar | Single-date with condition toggles | Condition-aware content, conventional predictions |
The longer, fairer version
Ebb: what we built and why. Everything on this list annoyed us into existence. Ebb predicts your period as a range with a stated confidence ("Jul 14–24 · 75% confident"), computed by an engine designed around cycle variability rather than averages, so when your cycles wobble, the range honestly widens instead of the app pretending. It's built to be useful specifically for PCOS-pattern cycles, and everything runs on your phone: no account, nothing uploaded (why we think that's non-negotiable). The free tier includes the full prediction engine, and the paid tier's price is shown up front. What Ebb is not: a pregnancy platform, a community, or a contraception method; apps below do some of those better.
Bearable: the honest outsider. Not strictly a period app: it's a symptom-and-factors tracker with cycle logging, and it wins our respect by refusing to predict at all: no due dates, no "you're late." If your goal is correlating symptoms with cycle phases (very useful for PCOS) and you don't want predictions, it's excellent. You give up prediction entirely, which is the honest version of not doing it well.
Clue: the best of the mainstream. Berlin-based, GDPR-governed, refreshingly scientific in its content, and upfront that predictions are less reliable for irregular cycles. Its predictions are still single-date-style and cloud-synced with an account (two structural choices that don't fit irregular cycles or strict privacy), but among big-name apps, it's the one we'd point a friend to.
Drip and Euki: the privacy champions. Open-source, repeatedly praised in Mozilla's privacy reviews, all data on-device. Prediction is basic (Drip) or absent (Euki); these are trackers first, forecasters barely, but if privacy outranks everything else and you want a free, audited tool, they're the honorable choice. We recommend them without hesitation to people who don't need prediction.
Flo: the giant. The most-downloaded tracker on earth, with genuinely useful content and features, an Anonymous Mode added post-2022 and, relevant here, a prediction model still built around confident single dates that irregular cycles routinely embarrass. If your cycle is regular, Flo is fine. This article isn't for regular cycles.
MyFlo, Ovia, and the condition-aware tier. Several apps let you flag PCOS or other conditions and adapt their content (useful), but under the hood, predictions remain conventional single-date output. Better bedside manner, same math.
How to choose in 60 seconds
- Cycles vary by a week or more, and you still want predictions → you want range-based honesty: that's Ebb's lane, by design.
- You want no predictions, deep symptom correlation → Bearable.
- You want zero-compromise privacy and minimal features, free → Drip/Euki.
- Your cycle is actually fairly regular and you want the full ecosystem → Clue, or Flo with Anonymous Mode.
And whichever you pick: log start dates consistently for three months before judging any app. Every engine on this list (ours included) is only as good as the history it's given. (Why predictions fail without it.)
FAQ
What's the most accurate period tracker for irregular cycles?
Reframe "accurate": for a variable cycle, a single-date prediction is never accurate except by luck. The accurate representation is a range with a confidence level that reflects your actual variability, which is the design premise of Ebb, and the reason Bearable opts out of predicting entirely.
Is there a period tracker made for PCOS?
Several apps offer PCOS content modes; fewer change their prediction math for PCOS-pattern cycles. Range-based prediction plus long-cycle tolerance is what to look for: more on PCOS-specific prediction here.
Which period trackers don't share your data?
The on-device set: Drip, Euki, Periodical, and Ebb. Full privacy breakdown here.
Do free period trackers work for irregular cycles?
Drip and Euki are free and private. Ebb's free tier includes the full range-prediction engine. "Free" mainstream apps monetize otherwise, and it's worth understanding how before logging intimate data.