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SEHATDOC clinic and hospital software

Period calculator

Enter the first day of your last period to predict your next periods. Nothing you type leaves your browser.

Your result appears here as you type.

How it works

Your cycle runs from the first day of one period to the first day of the next. A cycle of 21 to 35 days is usual in adults, and this calculator adds yours to the date you enter. If you do not know your cycle length, it uses 28 days.

When to see a doctor

  • Your cycle is often shorter than 21 or longer than 35 days.
  • You have missed three periods in a row and are not pregnant.
  • Bleeding is very heavy, or lasts more than seven days.
  • You have severe pain, or bleeding between periods or after menopause.

Last checked 31 October 2026. This calculator gives an estimate for information. It is not a diagnosis or medical advice, so talk to a doctor about your result.

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Common questions

Still unsure? Send us the question and a person — not a bot — will answer it.

How do I calculate my next period?

Add your usual cycle length to the first day of your last period. With a 28-day cycle starting on 1 March, the next period is due around 29 March.

What is a normal cycle length?

For most adults it is 21 to 35 days. It can vary by a few days from month to month.

Why is my period late?

Pregnancy is the first thing to rule out. Stress, weight change, illness, thyroid problems and polycystic ovary syndrome can also delay it.

Try it with next week’s patients

Plans start at PKR 4,000 a month, billed in rupees, with setup and staff training included. Bring over next week’s patients and see whether the evening session runs any easier.

Create your clinic accountBook a walkthrough instead

Setup help and staff training are included on every plan.