Using this calculator for a first period
Early cycles are often irregular, so treat any prediction here as a loose guide rather than a precise date. If you're not sure of a cycle length yet, the default 28-day estimate is a reasonable starting point.
A gentle note for parents
A first period can feel like a big milestone. Keeping period supplies on hand, talking openly, and reassuring that irregular timing is normal at first can make the experience much less stressful.
Frequently asked questions
What age does a first period usually happen?+
Most girls get their first period between ages 10 and 15, averaging around age 12. Starting a bit earlier or later can still be entirely normal.
Will my cycle be regular right away?+
Not usually. It's common for cycles to be irregular for the first one to two years after menarche while hormone patterns settle. Use this calculator's estimates loosely during that time.
When should we see a doctor?+
If periods haven't started by age 16, or if early periods are extremely heavy or painful, it's a good idea to check in with a pediatrician or gynecologist.