Irregular cycle & ovulation calculator.
Three inputs, an honest estimate. With PCOS, cycles are often irregular — so treat this as a map of the average, not a promise.
The first day of bleeding, not the last.
First day of one period to the first day of the next. If it varies, use your best average.
How many days you usually bleed.
About this calculator.
As orientation, yes — as a prediction, less so. Cycles longer than 35 days or fewer than 8 periods a year are a common PCOS sign, and they make calendar math unreliable. Tracking symptoms alongside dates (the guide's trackers are built for this) gives you far better information than any calculator.
No. Calendar estimates are not contraception and not fertility treatment — especially with irregular ovulation. If you're trying to conceive or avoid conceiving, talk to your clinician about methods that measure ovulation directly.
In short: higher androgens and insulin can disrupt the hormonal handoff that triggers ovulation. No ovulation, no predictable luteal countdown, no predictable period. Chapters 2, 3 and 6 of the guide draw the full picture in plain language.
Calculators are a guide. The Companion is the plan.
Understand what your cycle is doing and why — 46 pages, 32 lessons, printable trackers.
One-time $27 · 14-day refund, no questions.
Keep exploring the numbers.
PCOS symptom quiz.
Twelve questions, one per screen. See where your symptoms cluster.
Insulin-resistance checker.
A screening approximation of the mechanism behind many PCOS symptoms.
BMI calculator.
The reference metric, with interpretation written for PCOS.
Notice: this calculator is an educational estimate, not a medical device. It cannot diagnose PCOS, predict ovulation reliably in irregular cycles, or replace clinical fertility assessment. Nothing you enter is stored or sent anywhere.