Private · on-device
Period Predictor
Enter the first day of the last period to estimate the next few. In the first couple of years, cycles are often irregular — use this as a rough guide for packing your kit, not a promise.
🔒 Everything is calculated in your browser. Nothing you type is sent or saved. For teens, cycles between 21 and 45 days are common. If periods last more than 7 days, soak a pad or tampon every 1–2 hours, or stop for 3+ months after becoming regular, talk to a doctor.