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Period Tracker

Predict the next 6 menstrual cycles.

Best for: Use it to anticipate upcoming periods, plan ahead, or spot when your cycle is unusually early or late.

Complete guide
Why this result happened View assumptions
Country (units):

Input

How it's calculated & sources
The Period Tracker uses the standard formula for this calculation. It runs entirely in your browser, so your inputs are never uploaded. Figures are educational estimates, not professional advice — verify important decisions with a qualified expert. Last reviewed June 2026.
Key assumptions
  • Regular cycle assumed

Educational estimate only — not medical advice. Consult a qualified healthcare professional for decisions about your health.

Free & no sign-up · runs entirely in your browser. Results are estimates for general information, not professional advice — verify important decisions with a qualified expert. Last reviewed June 2026.

How it works

Predicts next 6 cycles from your last period date + average cycle length.

Example

LMP 2024-01-01, 28-day cycles → next periods on Jan 29, Feb 26, Mar 25…

Frequently asked questions

Is this medical advice?+

No. Use this as a planning aid only.

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Complete guide

Quick answers

Short, sourced answers to the questions people (and AI assistants) ask most.

What is Period Tracker?
A period tracker predicts the start dates of your next several menstrual periods from your most recent period date and your average cycle length.
Why does Period Tracker matter?
Due date and pregnancy milestones are counted from this date.
How is Period Tracker calculated?
It adds your cycle length to your last period's start date to predict the next start, then repeats to project the coming cycles. A typical cycle is counted from the first day of one period to the first day of the next. Formula: Next period start = Last period start + Cycle length (days).
What is a good period tracker?
Cycle lengths of about 21–35 days are considered normal, and some month-to-month variation is expected. Persistent irregularity is worth discussing with a clinician.
What are common period tracker mistakes?
Relying on predictions with irregular cycles, where accuracy drops.
When should you use the Period Tracker?
Use it to anticipate upcoming periods, plan ahead, or spot when your cycle is unusually early or late.

What is the Period Tracker?

A period tracker predicts the start dates of your next several menstrual periods from your most recent period date and your average cycle length.

How the Period Tracker works

It adds your cycle length to your last period's start date to predict the next start, then repeats to project the coming cycles. A typical cycle is counted from the first day of one period to the first day of the next.

Next period start = Last period start + Cycle length (days)

Understanding the inputs

What each value means, why it matters, and a typical range — so you can fill in the calculator with confidence.

Last Menstrual Period

The first day of your last menstrual period, used to date a pregnancy.

Why it matters:
Due date and pregnancy milestones are counted from this date.
Typical range:
A 28-day cycle is assumed unless you specify otherwise.
How it affects results:
  • Higher: A later date shifts the due date later.
  • Lower: An earlier date shifts the due date earlier.

Common mistake: Entering the conception date instead of the period's first day.

What impacts results most

  1. 1.
    Last period date (High impact)The base for the next-period estimate.
  2. 2.
    Cycle length (High impact)Sets the gap between periods.

Key assumptions

  • Regular cycle assumed

What's a typical value?

Cycle lengths of about 21–35 days are considered normal, and some month-to-month variation is expected. Persistent irregularity is worth discussing with a clinician.

Predicted period start days by cycle length (counting from day 1)

26 daysDay 27Day 53Day 79
28 daysDay 29Day 57Day 85
30 daysDay 31Day 61Day 91
32 daysDay 33Day 65Day 97

Worked example

With a 28-day cycle and a last period starting 1 January, the next is predicted around 29 January, then ~26 February.

Common mistakes to avoid

  • Relying on predictions with irregular cycles, where accuracy drops.
  • Using it as a contraceptive method — it is not reliable for that.
  • Forgetting to update your last-period date each month.

Reviewed sources & methodology

Methodology: Professional Estimate · Last reviewed June 2026.

Keywords: period, menstrual, cycle.

This tool is for general information only and is not medical advice. Consult a qualified healthcare professional for decisions about your health.

Sources: ACOG — Menstrual cycle

Reviewed by the Free Tools Galaxy editorial team · Updated June 2026 · Calculated privately in your browser.

Frequently asked questions

Is the Period Tracker free to use?+

Yes. Every tool on Free Tools Galaxy is 100% free, runs in your browser and requires no signup.

How accurate is the Period Tracker?+

Period Tracker uses the standard period tracker formula in double-precision arithmetic, so the same inputs always produce the same result and you can verify any figure by hand. It is an educational estimate — real-world outcomes depend on your actual rates, rules and assumptions.

Do you store my inputs?+

No. The Period Tracker runs entirely in your browser. Nothing is uploaded or saved to a server.

Can I use the Period Tracker on mobile?+

Yes — the interface is fully responsive and works on phones, tablets and desktops.

What are common mistakes to avoid?+

The most frequent mistake is mixing units. Double-check your inputs use a single, consistent unit before clicking Calculate.

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Title: I built/used this free period tracker — instant, no signup

Body: Predict the next 6 menstrual cycles. Try it: https://freetoolsgalaxy.com/tools/period-tracker
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Period Tracker on Free Tools Galaxy — Predict the next 6 menstrual cycles. https://freetoolsgalaxy.com/tools/period-tracker
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# Period Tracker — the free tool I keep coming back to

Predict the next 6 menstrual cycles.

Try it: https://freetoolsgalaxy.com/tools/period-tracker
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The fastest way is to use a free in-browser period tracker: https://freetoolsgalaxy.com/tools/period-tracker. Predict the next 6 menstrual cycles.

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