Short answer
Most women begin the menopausal transition between ages 45 and 55, according to the National Institute on Aging. It can start earlier: ACOG says estrogen levels begin to fluctuate in your 30s and 40s. There is no single start age, because perimenopause is defined by cycle changes, not by a birthday. Symptoms before 40 are worth a clinician visit.
The usual age range
The National Institute on Aging says most women begin the menopausal transition between ages 45 and 55, and that the process may last for several years. It puts the average age of menopause in the United States at 52.
ACOG describes the same window from the other end: perimenopause usually begins in your mid-40s, and estrogen production begins to fluctuate in your 30s and 40s. In the SWAN study, which followed 3,302 US women, the median age at the final menstrual period was 52.54 years.
How the start is defined
Researchers do not use age to mark the start. The STRAW+10 staging system, published in 2012, defines the early menopausal transition as a persistent difference of 7 days or more in the length of consecutive cycles. The late transition starts with a gap of 60 days or longer between periods and lasts, on average, 1 to 3 years.
STRAW+10 recommends applying these stages regardless of a woman's age. That is why a clinician will ask about your cycles first. It also means symptoms alone, without cycle changes, do not fit the research definition.
Earlier start, longer transition
SWAN researchers tracked daily menstrual calendars from 1,145 women. The adjusted median length of the transition ranged from 4.37 years in the women who started oldest to 8.57 years in the women who started youngest.
Smoking mattered. Current smokers started at an adjusted median age of 46.05 years, compared with 47.27 years for non-smokers. These figures do not tell you how common a start in the mid-30s is. No source reviewed here gives that number.
Before 40, get it checked
The Menopause Society defines premature menopause as menopause before age 40 and early menopause as between 40 and 45. Primary ovarian insufficiency, or POI, is loss of ovarian function before 40, with hormone production and periods that can return on and off.
The federal Office on Women's Health says about 5% of women naturally go through early menopause, and that you should talk to your health care provider if you think you may be reaching menopause early. Other conditions can cause similar symptoms, so a visit can sort out what is going on.
Related questions
Can perimenopause start at 35 or 36?
It can. ACOG says estrogen begins to fluctuate in your 30s and 40s, though most women start the transition between 45 and 55. Cycle changes or symptoms this early are a reason to see a clinician, not to assume.
How long does perimenopause last?
It varies. In SWAN, the adjusted median ranged from 4.37 years for the latest starters to 8.57 years for the earliest starters.
How do you know when you have reached menopause?
The National Institute on Aging says you only know you have reached menopause when you have not had a period or spotting for a full year.
Read next
Sources
- NIH National Institute on Aging: What Is Menopause? (content reviewed 16 Oct 2024)
- ACOG: The Menopause Years, FAQ047 (last reviewed December 2025)
- Harlow et al., J Clin Endocrinol Metab: Executive summary of the Stages of Reproductive Aging Workshop + 10 (2012)
- Paramsothy et al., Menopause: Duration of the menopausal transition is longer in women with young age at onset, SWAN (2017)
- The Menopause Society: The 2022 Hormone Therapy Position Statement of The North American Menopause Society (2022)
Published 2026-10-04 · Last checked 2026-10-04
Educational content, not medical advice. Made for the United States.