Period & Cycle Health

Period Calculator

Predict your next period date, see your next 12 periods on a calendar and check whether your period is late — made for Indian women.

Next 12 Periods Cycle Calendar Private — Nothing Saved

Enter your cycle details

Takes 20 seconds · No login required · Your dates never leave your device

Your name (optional)

First day of your last period

Average cycle length (days)

days

Period length (days)

days

Cycle length is counted from the first day of one period to the day before the next. Usually 28. If unsure, use 28.

Your Period Result

Next period & cycle estimate

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days to go

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Period Fertile window Ovulation

Next Period

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Period Lasts

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Next Ovulation

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ℹ

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Your period calendar

Your period Predicted period Fertile window Ovulation day Today

Your next 12 periods

⚠ Talk to a doctor if: your periods are often shorter than 21 or longer than 35 days apart, you miss three periods in a row, bleeding lasts more than 7 days or soaks through a pad or tampon every hour for several hours, you have severe pain, or you bleed between periods or after sex.

Medical Disclaimer: This calculator is for informational purposes only and is not a substitute for professional medical advice. Period dates are estimates and can vary from month to month. Please consult a qualified doctor for personalised guidance.

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Data Sources & Methodology

Clinical guidance and reference data behind this calculator

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Menstrual Cycle as a Vital Sign

ACOG · Committee Opinion 651

World Health Organization

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Your Menstrual Cycle

Office on Women's Health · US HHS

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WHO PCOS Fact Sheet

Irregular periods · WHO

What is a Period Calculator?

Period Calculator — Predict Your Next Period Date

A period calculator predicts when your next period will start, based on the first day of your last period and the length of your cycle. It is the quickest way to answer "when is my next period?".

Enter your details in the calculator above — no login, no signup. This period date calculator shows your next period date, how long it should last, your next 12 periods on a period calendar, and whether your period is late. If your cycles are irregular, add your shortest and longest cycle to see a likely range instead of a single date. Nothing you type is sent to our server.

How to Use This Period Calculator

Enter your last period

Choose the first day of your most recent period (the first day of bleeding).

Add cycle and period length

Use your usual cycle length (28 days if unsure) and how many days you bleed.

See your next period

Get your next period date, a countdown, and the next 12 periods on the calendar.

Check if it is late

If your period is late, the result tells you when to take a pregnancy test.

Period Formula

How Your Next Period Date Is Calculated

Your next period starts one cycle after your last one. There is only one calculation to do.

The period date formula

Next period = First day of last period + Cycle length

Period end date = Period start date + Period length − 1 day. Ovulation is about 14 days before the next period.

Worked Example

If your last period started on 5 Jan 2026, your cycle is 28 days and you bleed for 5 days, your next period is expected on 2 Feb 2026 and should end around 6 Feb. The next periods follow every 28 days:

Period	Dates	Starts on
Last period (entered)	5 Jan 2026 – 9 Jan	Monday
Predicted period 1	2 Feb 2026 – 6 Feb	Monday
Predicted period 2	2 Mar 2026 – 6 Mar	Monday
Predicted period 3	30 Mar 2026 – 3 Apr	Monday
Predicted period 4	27 Apr 2026 – 1 May	Monday
Predicted period 5	25 May 2026 – 29 May	Monday

Last period (entered)
5 Jan 2026 – 9 Jan
Starts on Monday

Predicted period 1
2 Feb 2026 – 6 Feb
Starts on Monday

Predicted period 2
2 Mar 2026 – 6 Mar
Starts on Monday

Predicted period 3
30 Mar 2026 – 3 Apr
Starts on Monday

Predicted period 4
27 Apr 2026 – 1 May
Starts on Monday

Predicted period 5
25 May 2026 – 29 May
Starts on Monday

Menstrual Cycle Phases

The Four Phases of the Menstrual Cycle

Your cycle is controlled by hormones and has four phases. The table below shows a typical 28-day cycle; the timing shifts if your cycle is shorter or longer.

Phase	Days (28-day cycle)	What happens
Menstrual phase	Days 1 to 5	The uterine lining is shed as your period. Estrogen and progesterone are at their lowest.
Follicular phase	Days 1 to 13	The ovary develops follicles, each holding an egg. Estrogen rises and the uterine lining rebuilds.
Ovulation	Around day 14	A mature egg is released. This is the most fertile time of the cycle.
Luteal phase	Days 15 to 28	Progesterone rises to prepare the uterus for pregnancy. If no pregnancy occurs, hormone levels fall, PMS symptoms may appear and the next period starts.

Menstrual phase · Days 1 to 5
The uterine lining is shed as your period. Estrogen and progesterone are at their lowest.

Follicular phase · Days 1 to 13
The ovary develops follicles, each holding an egg. Estrogen rises and the uterine lining rebuilds.

Ovulation · Around day 14
A mature egg is released. This is the most fertile time of the cycle.

Luteal phase · Days 15 to 28
Progesterone rises to prepare the uterus for pregnancy. If no pregnancy occurs, hormone levels fall, PMS symptoms may appear and the next period starts.

Want to know your fertile days? Try our Ovulation Calculator.

Normal vs Irregular Periods

What Is a Normal Period? Regular vs Irregular Cycles

Cycle length: 21 to 35 days is normal for adults. In the first years after periods start, 21 to 45 days can be normal.
Period length: bleeding usually lasts 2 to 7 days.
Variation: a difference of up to 7 to 9 days between your shortest and longest cycle is considered normal.
Common causes of irregular periods: PCOS, thyroid problems, stress, sudden weight change, intense exercise, breastfeeding, some medicines and perimenopause.

Irregular periods are common among Indian women, and PCOS and thyroid conditions are frequent causes. If your periods are often irregular, you can check your symptoms with our PCOS Analyzer and Thyroid Health Quiz, then speak to a doctor. Guidance on normal cycle ranges is published by ACOG and MedlinePlus.

Late Period

Late Period? When to Take a Pregnancy Test and When to See a Doctor

A period that is a few days late is common and often not serious. Pregnancy is the first thing to rule out.

Take a home pregnancy test on or after the first day of your missed period for the most reliable result.
If the test is negative and your period still has not started, repeat it after 3 to 7 days.
Other causes of a late period include stress, illness, travel, weight change, PCOS, thyroid problems and breastfeeding.
See a doctor if your period is more than a week late and tests stay negative, if you miss three periods in a row, or if late periods keep happening.

If your test is positive, use our Pregnancy Due Date Calculator to find your due date.

Common Questions

Frequently Asked Questions

What is a period calculator?

A free period calculator predicts your next period date from the first day of your last period and your cycle length. It also shows how long your period should last, your next 12 periods and whether your period is late. The dates are estimates, not a diagnosis.

→ Ovulation Calculator → Pregnancy Due Date Calculator → PCOS Analyzer → Thyroid Health Quiz

Add your cycle length to the first day of your last period. For example, if your last period started on 5 January and your cycle is 28 days, your next period is expected on 2 February. Your cycle length is counted from the first day of one period to the day before the next one.

For most adults a normal cycle is 21 to 35 days, with an average of about 28 days. In the first few years after periods start, cycles of 21 to 45 days can be normal. A cycle that varies by up to 7 to 9 days from month to month is also considered normal.

A period usually lasts 2 to 7 days. Bleeding that regularly lasts longer than 7 days, or that soaks through a pad or tampon every hour for several hours, is a reason to see a doctor.

Pregnancy is the first thing to rule out. Other common causes are stress, illness, travel, sudden weight change, heavy exercise, PCOS, thyroid problems, breastfeeding and perimenopause. A period that is late once is usually not a concern, but see a doctor if it keeps happening or you miss three periods in a row.

Home pregnancy tests are most reliable from the first day of a missed period. If the test is negative and your period still has not started, repeat it after 3 to 7 days. See a doctor if your period is more than a week late and tests stay negative.

It is accurate only if your cycles are regular. With a regular cycle, most periods arrive within a day or two of the predicted date. If your cycles vary, add your shortest and longest cycle to see a likely range instead of a single date.

Irregular periods are common and can be caused by PCOS, thyroid disorders, stress, weight changes, intense exercise, breastfeeding, some medicines and perimenopause. If your cycles are often shorter than 21 days, longer than 35 days, or you skip periods, talk to a doctor. You can also try our PCOS Analyzer and Thyroid Health Quiz.

Period length is the number of days you bleed, usually 2 to 7. Cycle length is the number of days from the first day of one period to the first day of the next, usually 21 to 35. This calculator needs both.

अपने पिछले पीरियड के पहले दिन में अपने चक्र की औसत लंबाई (आमतौर पर 28 दिन) जोड़ें। ऊपर दिए गए कैलकुलेटर में तारीख और चक्र की लंबाई डालें — आपको अगले पीरियड की तारीख और अगले 12 पीरियड का कैलेंडर तुरंत मिल जाएगा। अनियमित पीरियड में अनुमान बदल सकता है, इसलिए अपने डॉक्टर से सलाह लें।

Last reviewed: May 2026 Based on ACOG & WHO guidance Free — No login required

Results are estimates. Consult a doctor before making health decisions.