The average age of natural menopause in the UK is 51, with a normal range from about 45 to 55. Before 45 is early; before 40 is premature ovarian insufficiency, which is a medical diagnosis rather than a variation.
Several factors shift the timing, and this estimator weighs the ones with the strongest evidence.
Your mother's age at menopause is the single best predictor. Genetics account for roughly half the variation between women.
Smoking brings it forward by one to two years on average, and the effect is dose-related.
Body weight. Very low body weight is associated with earlier menopause; fat tissue produces oestrogen, which is part of why.
Number of pregnancies. Women who have had children tend to reach menopause slightly later.
Some autoimmune conditions and treatments including chemotherapy also bring it forward substantially.
Modestly. No calculator can predict your menopause with precision, because the underlying factor is how many eggs you started with and how fast they are being used, neither of which is measurable in a useful way.
Blood tests do not solve this either. AMH gives a rough indication of remaining ovarian reserve, and it has been studied for menopause prediction, but individual accuracy is limited. FSH varies so much through perimenopause that a single reading tells you little.
Treat the result as a range rather than a date.
Earlier menopause carries real consequences, and knowing your likely timing changes what you monitor.
Fewer years of oestrogen exposure means higher lifetime risk of osteoporosis and cardiovascular disease. Women reaching menopause before 40 have roughly double the risk of type 2 diabetes compared with those reaching it between 45 and 54.
This is why early menopause is treated as a medical situation, usually with hormone therapy recommended until the average age of natural menopause, rather than as a personal preference.
Fertility is the other consideration. Fertility declines meaningfully in the decade before menopause, so a woman with a family history of early menopause who wants children may want that conversation sooner.
The transition usually begins four to eight years before your final period. The first sign is typically a change in cycle length rather than symptoms.
If your cycles have shortened by seven days or more, that suggests early perimenopause. Gaps of 60 days or more suggest late perimenopause.
Menopause itself is confirmed only in hindsight: twelve consecutive months without a period.
Related reading: What age does menopause start? · Early menopause before 45 · The first signs of perimenopause · Menopause and diabetes risk
Educational only, not medical advice. This is an estimate based on population data, not a prediction.