Period calculator: where am I in my cycle?
Enter the first day of your last period to see your cycle day, which phase you're probably in, what that phase is often like, and when your next period may start. It runs in your browser, and nothing is sent anywhere.
Mochi Moon learns your real cycle, and your partner gets their own free app with what helps in each phase.
How the calculator works
Day 1 is the first day of your period. The calculator assumes ovulation happens about 14 days before your next period, which is how most calendar methods estimate it, and splits your cycle into four phases:
- Menstrual (your period): energy is often lowest. Rest Mode.
- Follicular: energy and mood often rise. Planning Mode.
- Ovulatory: often the most social, confident days. Main Character Mode.
- Luteal: winding down, and PMS can show up in the last days. Cozy Mode.
Everyone is different, so treat this as a friendly estimate. Read more in the 4 phases of the menstrual cycle and how accurate period predictions are.
FAQ
How do I know what phase of my cycle I'm in?
Count from the first day of your last period (day 1). Days 1 to about 5 are your period (menstrual phase), then the follicular phase until around ovulation, which is usually about 14 days before your next period. The days after ovulation until your next period are the luteal phase.
How accurate is a period calculator?
It's an estimate based on averages. Cycles vary from month to month, and ovulation can shift. Tracking a few cycles in an app gives a more personal prediction, but no calculator is exact.
Can I use this to avoid pregnancy?
No. Fertile-window estimates from a calendar calculator are not a method of birth control. Talk to a healthcare provider about contraception that works for you.
What is a normal cycle length?
For adults, cycles commonly range from about 21 to 35 days. Some sources use 24 to 38 days. What matters most is what's normal for you, and big changes are worth mentioning to a doctor.
Does this calculator save my data?
No. Everything is calculated in your browser and nothing is sent anywhere.
This tool gives general estimates, not medical advice, and it is not a method of birth control. If your periods are very irregular, very painful or very heavy, or you've missed 3 or more, talk to a doctor.