Flo Premium — Cycle & Fertility Tracker

Flo works by learning from what you log — period dates, symptoms, basal temperature if you take it, ovulation test results if you use them — and its fertile-window predictions get noticeably sharper the more consistently you feed it data over two or three cycles. The daily check-ins and symptom insights make the trying-to-conceive process feel less like a black box, with the app flagging your predicted fertile window and offering context on what different symptoms might mean rather than leaving you to interpret everything yourself.

Used alongside the Femometer basal thermometer in this category, the two genuinely complement each other rather than compete: Flo predicts your upcoming fertile window from patterns and cycle history, while the thermometer confirms after the fact that ovulation has actually happened via the temperature shift. Flo alone is prediction, not confirmation — it cannot tell you with certainty that ovulation occurred, only that it is statistically likely around a given date based on your history, which is a meaningful distinction if you are trying to pinpoint fertile days with precision rather than a general estimate.

This suits people who want an easy, low-effort way to track cycles and get predictive insight without manually charting anything, and who are likely already comfortable using period-tracking apps. It is the natural default given how widely used it already is — no learning curve, slick interface, works quietly in the background of your day. If you want hard physiological confirmation of ovulation rather than a prediction, or you are trying to conceive with genuinely irregular cycles that make pattern-based prediction less reliable, pairing it with (or leaning more heavily on) basal temperature tracking makes more sense.

The catch is the subscription: £8.99 a month or £39.99 a year is a real ongoing cost, and it is only worth paying for the trying-to-conceive-specific features — ovulation predictions, symptom insights, TTC-focused content — if you are actively using them. If you only want basic period logging, the free tier covers that perfectly well, so it is worth being honest with yourself about which features you will actually use before committing to the paid tier.