First period calculator
Estimate when your first period will start. Free, private, no sign-up.
How the first period calculator works
Menarche (your first period) typically arrives about 2–2.5 years after breast development begins (Tanner stage 2). Girls who have started noticing white or clear vaginal discharge usually get their first period within 6–12 months. This calculator combines age, breast stage, and discharge to produce a rough estimate. For a personalized, updating prediction, install the free Bloomy app.
Frequently asked questions
How does a first period calculator work?+
It uses your age plus early puberty signs (breast development, discharge, growth spurts) to estimate when menarche will occur — usually within a 6-month window.
What's the average age for a first period?+
The average age is 12 in the US, but anywhere from 10 to 15 is normal. It typically arrives about 2 years after breast buds appear.
Can this calculator tell me the exact date?+
No calculator can. For a more precise ongoing prediction, use the free Bloomy app, which updates your estimate as you log new signs.
Is a first period age calculator accurate?+
Age-based calculators give you a realistic window (usually within 6–12 months), not an exact date. Adding puberty signs like discharge and breast stage makes the estimate tighter.