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Yellow is normal — especially early on. It means Daysy is still building your personal pattern and isn't ready to classify the day with certainty. Most women see more yellow in their first one to three cycles, with green days increasing as the algorithm learns their rhythm. Yellow isn't a problem. It's Daysy being careful before it commits.

Most users see green days within their first cycle. The number grows as Daysy learns your pattern — by cycle two or three, most women have a clear, consistent picture of their fertile and non-fertile days. The first cycle has more yellow days than later ones, and that's expected. Daysy is building your personal baseline from scratch — give it the full cycle and the picture becomes clearer.

Yes — and it handles variation better than most tracking methods. Daysy evaluates each cycle individually rather than averaging your history, so it adapts whether your cycle runs 28 days one month and 36 the next.

Early cycles will have more yellow days as Daysy builds your personal pattern - that's the algorithm learning, not a limitation. If your cycles are consistently longer than 40 days, speak with a clinician before purchasing. If you're unsure whether Daysy is right for your situation, your clinician is the right first conversation.

With irregular cycles, Daysy typically needs one to three cycles to build a reliable pattern. You'll likely see more yellow days in the first cycle — that's Daysy learning your rhythm, not a sign something's wrong. Most women in this situation have a much clearer picture by cycle three, as the algorithm adapts to your specific temperature signals.

Daysy handles cycle variability well. Its algorithm evaluates each cycle individually rather than averaging your history — so it adapts whether your cycle runs 28 days one month and 38 days the next. That's what makes it different from apps that predict based on past averages: Daysy responds to what your body is doing now, not what it did last time.

Daysy works for cycles between 19 and 40 days. If your cycles regularly exceed 40 days, it's outside the range Daysy is designed for — the algorithm needs data within that window to classify with confidence. For cycles consistently above 40 days, we recommend speaking with a clinician before purchasing. When cycle length sits outside typical range, clinical investigation gives you better answers than any tracking device can. If your cycle occasionally runs longer but isn't consistently above 40 days, that's a different picture — Daysy can still build a reliable pattern for you.

Not yet — but the timing is closer than most women expect. Prolactin, the hormone that supports milk production, suppresses ovulation and affects basal body temperature, which means the signals Daysy relies on aren't reliable during this period. Most women start using Daysy once their first postpartum cycle returns, typically around six weeks after breastfeeding ends. If you're unsure about timing, your GP or midwife can advise.

Yes. Missing an occasional reading won't erase your progress — Daysy recognises patterns over time, not through perfect daily input. Daysy needs at least three hours of uninterrupted sleep before your morning reading, so on nights that weren't settled — shift changes, jet lag, illness, or a rough night — skip the reading. Consistent readings on settled mornings are what build your cycle picture. Daysy is designed for real life, not laboratory conditions.

Yes. The DaysyDay app is included at no additional cost and has no subscription fee. Your S$449 covers the device and lifetime app access on iOS and Android.

Three differences that matter: Daysy measures to 0.018°C — about five times more precise than wearable alternatives. There's no subscription and no separate thermometer required. And Daysy's algorithm is built on 40 years of research and reads your actual temperature each morning, rather than predicting from cycle averages the way apps do.

It means the accuracy figure has been tested in published research, not just claimed. A peer-reviewed study followed 5,328 users across approximately 107,000 cycles — published in the European Journal of Contraception & Reproductive Health Care (van de Roemer et al., 2021). Daysy's algorithm has been evaluated across 17 clinical studies in total. Clinically validated means there is a body of evidence.