Frequently asked questions

What is Period Calc?

Period Calc (حاسبتي in Arabic) is a period tracker and planner for iPhone made for Muslim women. It predicts your next period, fertile days and ovulation, shows the Hijri date on every calendar day, lists your fasting days each month and includes a prayer & purity guide.

How does Period Calc predict my period, and how accurate is it?

It averages the length of your last six logged cycles, ignoring gaps longer than 90 days such as a pregnancy. Until you have logged two periods, it uses the cycle length you chose. Ovulation is estimated 14 days before your next expected period, and your fertile window runs from 5 days before ovulation to 1 day after. The more you log, the closer the estimates get, and the app tells you when your cycles vary a lot. You can try the same rule in the free period calculator. Predictions are estimates — not medical advice and not a method of contraception.

I don’t remember the exact day my last period started. Can I still begin?

Yes — a close guess is fine. You can change the date later, and the more periods you log, the closer the predictions get.

Which languages does Period Calc support?

More than 50. The app starts in your phone’s language, and you can change it any time in Settings.

Is Period Calc available on Android?

Not yet. Period Calc is available for iPhone on the App Store. The free period, ovulation and due date calculators on this website work in any browser, on any phone.

Where is my data stored?

On your phone only. There is no account and no sign-in, and your cycle data and notes are never sent to us. The app sends anonymous usage steps — which screens and buttons are used, never your health data — and you can turn them off in Settings › Privacy. Read the Privacy Policy.

Can I lock the app?

Yes. Turn on the app lock to protect it with a 4-digit PIN, and unlock it with Face ID or Touch ID if you like. Reminders are discreet by default, with no details unless you turn them on.

Do the calculators on this website save what I type?

No. They run entirely in your browser. This website uses no cookies and no analytics, and loads nothing from other companies.

Which Hijri calendar does Period Calc use?

The Umm al-Qura calendar. If the month starts a day earlier or later where you live, adjust the Hijri date by one or two days in Settings › Language & calendar.

What does the prayer & purity guide do?

While you bleed, it shows which day of your bleeding it is and the general limits of the Hanafi, Maliki, Shafi’i and Hanbali schools; when your period ends, it explains ghusl and the signs of purity. It gives general rules, not a fatwa — for your own case, ask someone whose knowledge you trust.

Does Period Calc help with fasting?

Yes. Every month it lists your fasting days — Mondays and Thursdays, the White Days, Arafah, Ashura and the six days of Shawwal — and marks the days your period is expected. With Premium you get a reminder the evening before, and a plan to make up missed Ramadan fasts on days your period is not expected.

Is Period Calc free?

Yes. Period predictions, the calendar with Hijri dates, your fasting days, trying-to-conceive dates, the prayer & purity guide, reminders, the app lock and pregnancy mode are free. Premium is an optional subscription for planning ahead.

What does Premium add?

The fasting planner with reminders, your best days to conceive and today’s chance of pregnancy, a PDF report for your doctor, purity reminders, a 12-month forecast, daily tips and symptom patterns, the make-up fast, Ramadan and Hajj planners, and CSV export.

How do I cancel Premium?

On your iPhone, open Settings › your name › Subscriptions, choose Period Calc and tap Cancel Subscription. Cancel at least 24 hours before the renewal date; you keep Premium until the end of the period you paid for. More help.