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Track your menstrual cycle, predict your next period, and plan ahead with ease. Get accurate estimates based on your personal cycle details.
Better cycle
Awareness
for a healthier
you
Fill in the details below to get the estimated period dates and cycle calendar.
Enter your details and press Calculate to see your estimated dates here.
A period calculator is a projection based on the average of your past cycles, not a measurement. If your cycles are genuinely regular, predictions usually land within a few days. If they vary, a prediction can be out by a week or more — which is exactly why we show a window and not a single guaranteed date.
Use your average from the last few cycles rather than a single cycle, and treat the result as a rough guide. Irregular cycles are common and often benign, but if yours change suddenly, stop, or come with heavy bleeding or pain, a healthcare professional should take a look rather than a calculator.
Yes, it is useful for understanding your cycle and roughly when you are fertile. It is not a medical assessment of fertility, and calendar timing cannot guarantee conception. If you have been trying for 12 months under 35 or six months over 35 without success, speak to a clinician.
The most common reasons are stress, illness, a change in routine, weight change, or ovulation happening later than usual in that cycle. Hormonal contraception and pregnancy are also common causes. A single late period is usually not a concern on its own, but repeated missed periods are worth investigating.
Estimate as closely as you can — the day you first noticed bleeding is the best anchor available. Being a few days out will shift every predicted date by the same amount, so the pattern stays useful even when the exact day is uncertain.
No. This is a general educational tool that performs date arithmetic. It cannot diagnose anything, cannot confirm or rule out pregnancy, and is not a substitute for professional care. For anything that affects your health, speak to a qualified healthcare professional.
Understand your cycle, track important dates, and take charge of your reproductive health.
Explore Health HubThere are only two inputs and one repeating rule. Once you understand the rule you can reproduce any date on this page by hand.
Ovulation is estimated at cycle length minus 14 days, the widely used convention that assumes a roughly two-week gap between ovulation and your next period. Every other figure here — the fertile window, the ovulation day, the coloured bands on the calendar — is derived from that same anchor date, so they cannot contradict each other.
A prediction is a projection, not a promise. Knowing which of these applies to you is more useful than recalculating.
Two or more missed periods in a row, or a cycle that suddenly becomes much longer or much shorter, is worth raising with a healthcare professional rather than recalculating.
The calendar switches between monthly, three-month and six-month views so you can see either the detail or the pattern.
Two habits make the output far more accurate. Use the average length of your last few cycles rather than a single cycle, and log the actual start date when it arrives — if the prediction is consistently a few days out, your real cycle length is simply not the number you assumed.
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