No. The Nadi calendar tool overlays onto the calendar you already use — Google or Apple. Nothing new to download. And our education and support doesn’t require any app at all, it will be provided through newsletters and events.

No. Nadi provides education and awareness, not diagnosis or treatment. We always encourage professional support where appropriate.

Period tracking gives you dates you will bleed. Nadi helps you understand all the phases of your cycle, and helps you understand what those phases might mean for your energy, focus, and capacity.

No. We’re not about rigid rules. We’re about understanding your patterns so you can plan more realistically.

No. Irregular cycles still offer useful patterns and signals. Nadi supports awareness, not perfection.

Nadi uses three inputs you provide: your last period start date, your average period length, and your average cycle length. From these, it calculates your four phases — menstrual, follicular, ovulatory, and luteal. The ovulatory window is estimated by counting backwards from the predicted start of your next cycle, based on the well-established principle that ovulation typically occurs 12–16 days before your next period begins.

Yes. The core approach is grounded in peer-reviewed research. The 6-day ovulatory window is based on landmark studies by Wilcox, Weinberg, and Baird (New England Journal of Medicine, 1995) which established that conception can only occur during the 5 days before ovulation plus the day of ovulation itself. This was confirmed in a follow-up study in the BMJ (2000) analysing 696 cycles using urinary hormone markers.

Nadi provides estimates based on your averages, not precise predictions — and we’re upfront about that. Research confirms that no calendar-based method can pinpoint the exact day of ovulation (Johnson, Marriott & Zinaman, Current Medical Research and Opinion, 2018). Only methods using physiological markers like hormone testing or basal body temperature can do that. What Nadi does is give you a useful, research-grounded framework for understanding your cycle phases so you can plan with more awareness.

This is a common assumption, but the science says otherwise. A large-scale study of over 612,000 cycles (Bull et al., npj Digital Medicine, 2019) found the average luteal phase was 12.4 days, with a range of 7–17 days. A 2024 study in Human Reproduction (Henry et al.) tracked women over a full year and found that 55% experienced at least one short luteal phase during that time. Cycles are more variable than textbooks suggest — which is exactly why awareness tools like Nadi are useful.

No. Nadi is a cycle awareness and wellbeing tool. It’s designed to help you understand your patterns, not to replace medical advice or contraception. If you need precise ovulation detection, we’d encourage you to speak to a healthcare professional about methods that use physiological markers.

Wilcox, A.J., Weinberg, C.R., & Baird, D.D. (1995). New England Journal of Medicine, 333(23), 1517–1521.

Wilcox, A.J., Dunson, D., & Baird, D.D. (2000). BMJ, 321(7271), 1259–1262.

Bull, J.R., Rowland, S.P., Scherwitzl, E.B., et al. (2019). npj Digital Medicine, 2, 83.

Henry, S., Shirin, S., Goshtasebi, A., & Prior, J.C. (2024). Human Reproduction, 39(11), 2565–2574.