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Period tracker calculator

When is my next period?

When your next period is due, and where you are in the current cycle.

Your usual cycle length

days

First day of one period to the first day of the next

How long your period lasts

days

Days since your period started

days

0 if it started today

These are example numbers. Replace them with yours, then press Calculate.

Example answer

14days to next period

more than a week away

Earlier in the cycle. The fertile window shown above is the part that matters if you are trying.

This is a guide, not a diagnosis. Share the result with your doctor.

Your result on the scale

The ranges this calculator uses. Yours is highlighted.

Your numbers

Everything worked out from what you entered.

Cycle day today: day 15
Next period: in 14 day(s)
Period expected to last: 5 day(s)
Estimated ovulation: around day 14
Fertile window: day 9 to day 15

What each result means

Your result is highlighted. Your own clinic's advice always comes first.

Your resultoverdue

Your period is later than your usual cycle length. A pregnancy test is the first thing to do. Occasional late or missed periods also follow illness, stress, weight change or travel.

Your resultdue today

Due today based on your usual cycle. Cycle length normally varies by a few days either side.

Your resultwithin a week

Approaching. If you are tracking to conceive, the fertile window has already passed for this cycle.

Your resultmore than a week away

Earlier in the cycle. The fertile window shown above is the part that matters if you are trying.

Where this fits in your journey

The usual order, from trying to conceive to pregnancy. Not everyone needs every stage. This calculator belongs to stage 1.

Stage 1 · you are here

Trying to get pregnant

Timing and the basics, before any treatment.

This calculator: When is my next period?

Calculators for what comes next

How this is worked out

Date calculationExact arithmetic on the dating convention named below. Scan dating by your clinic takes precedence.

Projects your next period from your own cycle length. Useful for planning; not reliable as contraception, and not a substitute for a pregnancy test if a period is late.

About this calculator

?What it tells you

Your next six periods, and whether your cycle looks regular. When your next period is due, and where you are in the current cycle.

✓When to use it

Monthly, or when your cycle has changed and you want to check

iWhat you need

Your usual cycle length (days)
How long your period lasts (days)
Days since your period started (days)

!What it cannot tell you

A projection from your usual cycle length. Cycle length varies between cycles in most people.

Common questions

My cycle length changes every month. What should I enter?

Use your average over the last few months. If it varies by more than about four days, treat the result as a rough guide, and consider that persistently irregular cycles are worth investigating.

Does a late period always mean pregnancy?

No. Illness, stress, weight change, travel, thyroid problems and PCOS all delay periods. A test is still the quickest way to rule pregnancy in or out.

Sources

Projection from the cycle length you enter, assuming a 14-day luteal phase. Cycle length varies between cycles in most people. Not a contraceptive method.

In an emergency

If you have any of the warning signs listed here, don't wait for a test result or a calculator. Get help now.

112All emergencies, anywhere in India 108Ambulance

Also call your IVF clinic. Most clinics give an emergency number on your treatment or discharge sheet. Save it in your phone now, before you need it.