Perimenopause Period Change Calculator

Enter your age, recent cycle changes and symptoms to see which stage of the perimenopause transition your periods suggest, what usually comes next, and what to raise with your clinician.

What counts as a perimenopause period change

Cycles shortening or lengthening by seven days or more, skipped periods, heavier or lighter bleeding and worsening premenstrual symptoms are the usual early signals of the transition.

How the calculator works

It combines your age, cycle regularity, gaps between periods and current symptoms to place you on the early, late or post-transition part of the journey, with a plain-language explanation of the reasoning.

Why cycle patterns beat a single blood test

Hormones swing day to day in perimenopause, so a single FSH or oestrogen result can mislead. Your pattern of period changes over several months is the more reliable signal.

What to do with your result

Pair it with a symptom log — hot flashes, sleep, mood and brain fog — so your appointment starts with counted data rather than recall.