A period tracker that works without an account
This period tracker runs entirely in your browser. You don’t need to download an app, create a login or give an email address. Open the page, add your last period, and you’ll get a first estimate straight away. Your record is saved on this device, and it’s there when you come back.
Unlike a one-off period calculator, which starts from a number you enter, the tracker works from what actually happened. The more you log, the more its predictions reflect your own body.
How your predictions are worked out
- Your periods come from the flow you log. Spotting isn’t counted as the start of a period, and one blank day doesn’t split a period in two.
- Your typical cycle is the middle value of your last 12 cycles. That means one unusual month doesn’t throw off your next prediction.
- Your date range reflects your own variation. Once you’ve logged 3 or more cycles, the tracker measures how much your cycle varies. Until then, it assumes about 3 days either side.
- Long gaps are handled separately. A gap of more than 90 days is left out of your predictions and flagged, as it’s worth discussing with a doctor.
You can read every rule the tracker uses, including its limits.
What’s worth logging
| What to log | Why it helps |
|---|---|
| Flow | Sets your period dates, which drive every prediction. It’s the only thing you need to log. |
| Colour | Shows how your bleeding usually changes, so a difference is easier to notice. The photo check can help. |
| Symptoms and mood | Shows which period symptoms you get, and when. The NHS suggests keeping a diary for at least 2 cycles if PMS is affecting you. |
| Cervical mucus | Thin, clear, stretchy mucus can suggest you’re close to ovulation. |
| Temperature | A small, sustained rise suggests ovulation has already happened, which helps you learn your pattern over several cycles. |
Using your record at an appointment
Your summary gives a doctor the basics at a glance. It lists your recent periods, how long you bled, and the number of days between each one.
A record is especially useful if your periods have become irregular, you’ve missed three in a row, you bleed between periods, or your periods are very heavy or painful. These are all good reasons to speak to a GP.
Sharing your data
Your log stays private until you decide otherwise. Open the sharing panel above and you can:
- Share a summary through your device’s share menu, by email, or as text to copy.
- Choose the details. Dates and cycle lengths are always included. Symptoms, temperature and notes are left out unless you tick them, and you can preview the exact text first.
- Download a spreadsheet in CSV format, which opens in Excel, Numbers or Google Sheets.
- Send everything to your other device as a backup file, then restore it in the tracker there.
- Print a summary to take to an appointment, or add date reminders to your calendar.
Once you’ve sent something, it’s subject to the privacy rules of the app and the person who receives it. A file or message stored elsewhere isn’t covered by this site’s protections, so send it only to people and services you trust.
Keeping your log safe
Because this device holds the only copy, clearing your browser data erases your log. Some browsers can also clear data from sites you haven’t visited for a while. Save a backup every so often, and before you change phone or browser. Anyone using this browser could open your tracker, so on a shared device, use a private browser profile.
What the tracker can’t do
Predictions are estimates and must not be used as contraception. Hormonal contraception also changes your cycle, so predictions may not apply if you’re using it. If your period is late, use the late period checker to see what might explain it.