How to Track Your Menstrual Cycle Accurately

Count cycle length correctly

A cycle is counted from the first day of one period — the first day of real bleeding, not spotting — to the day before the next period starts. Adult cycles commonly fall between about 24 and 38 days, and in the first years after periods begin they are often longer and more variable while the cycle settles.

What to record each cycle

• Start and end dates of bleeding.
• Flow, using the same rough scale each time.
• Pain, with severity and whether it interfered with normal activity.
• Spotting between periods, with dates.
• Symptoms across the cycle — mood, sleep, headaches, energy, breast tenderness.
• Anything you took, including pain relief and supplements.

Why three cycles is the minimum useful record

One cycle is an anecdote. Three or more show your normal range, which is the thing that matters — a 27-day cycle is only interesting relative to your own pattern. Cycle-to-cycle variation of a few days is common.

Changes commonly considered worth discussing

General guidance from public health bodies suggests raising these with a clinician: periods that stop for three months or more without pregnancy, bleeding between periods, bleeding after sex, periods that become much heavier or much longer than usual, cycles consistently shorter than about 21 days or longer than about 35 days in adults, severe pain that stops you doing normal things, and any bleeding after menopause. This is not a diagnostic list — it is a prompt to have the conversation.

On predicted dates

Any date an app projects is arithmetic on the dates you entered. It is an estimate of when a period might start based on your history, not a prediction of ovulation or fertility, and it must never be used as contraception.

How HarmoFlux helps

HarmoFlux records cycle dates, flow, pain and the symptoms around them, and keeps that history continuous as your stage of life changes — early cycles, the reproductive years, perimenopause and beyond.