Period Calculator
Predict your next period and track your menstrual cycle. Get a 6-month calendar forecast of your future periods and ovulation dates.
Days between periods (default 28).
How long bleeding lasts (default 5).
How does the Period Calculator work?
The menstrual cycle is a repeating biological rhythm. While every body is unique, this calculator uses the standard "rhythm method" logic to project future dates.
- Cycle Start: Day 1 is the first day of bleeding.
- Next Period: We add your average cycle length (e.g., 28 days) to the start date to find the next period.
- Ovulation: Ovulation typically occurs 14 days *before* the next period begins.
Why track your cycle?
Tracking isn't just for pregnancy planning. It helps you:
- Predict Bleeding: Avoid surprises and plan vacations or events around your period.
- Understand Symptoms: Knowing you are in the luteal phase (post-ovulation) can explain PMS symptoms like bloating or mood changes.
- Monitor Health: Irregular cycles can be a sign of health issues like PCOS or thyroid problems.
Cycle Regularity
A "regular" cycle lasts between 21 and 35 days. If your cycle varies by more than a few days each month, these predictions will be estimates. Stress, diet, and travel can all delay your period.
Trying to get pregnant? Use our Ovulation Calculator for a detailed look at your fertile window.
? Frequently Asked Questions
Yes, 28 days is the medical average, but anything from 21 to 35 days is considered a healthy, normal menstrual cycle.
You can, but the predictions may not be accurate. If your cycle length changes every month, try entering the average of your last 3 months.
Yes, our date calculations automatically handle leap years and varying month lengths.
The luteal phase is the second half of your cycle, from ovulation until your period starts. It is usually consistent (around 14 days) even if the first half of your cycle varies.