What’s the best period tracker for irregular cycles and PCOS?

Why single dates let you down

When cycles vary, a single predicted day is often wrong, and an app that keeps moving it can feel like your body is failing. A range is more honest: it says when your period is likely, and how sure the app is. The NHS says irregular periods are common and not usually a sign of anything serious, but worth checking with a GP if they change.

What to look for

• A range, not a date. And one that widens when your cycles vary.
• A way to tell the app. A setting for irregular cycles or PCOS.
• Learning from your own cycles. Not a fixed 28-day average.
• Ways to refine it. Logging temperature or ovulation tests can narrow the window.
• When to see a doctor. Gentle prompts if cycles are very short, very long, or stop.
• A doctor summary. Dates, lengths and symptoms on one page.

How the apps compare

• Seventh: predictions are always a range. Irregular-cycle and PCOS settings widen it, and a confirmed temperature rise or a positive ovulation test can narrow it. It prompts you to check with a doctor if a period hasn’t come for 90 days. The doctor summary is free.
• Flo: its help centre describes a countdown to your period with predicted days in the calendar. Flo Premium includes a Symptom Checker that asks whether symptoms may match PCOS or endometriosis; Flo says it isn’t available in the UK or EU.
• Clue: predictions use up to your last 12 cycles, and you can hide atypical cycles from the calculation. We found no PCOS-specific feature in Clue’s help centre on 28 October 2026.

How Seventh handles your data

Seventh never sells your data, shows no ads, and has no third-party trackers or advertising SDKs. It works without an account; if you sign in, your cycle is backed up to our servers so it can be restored. Seventh counts app usage itself, without any health values. Every detail is in Seventh’s privacy policy.