Menstrual Cycle (Period) Calculator
From last period and cycle length, estimate the next period and ovulation date.
Input Data
Last Year
1–12.
1–31.
Cycle
days
Results
Estimated next period date (YYYYMMDD).
20,260,829
Next period and ovulation explanation.
下次月經 ≈ 2026-08-29；排卵日 ≈ 2026-08-15（估算）。
At a glance:Next period = last + cycle length; ovulation ≈ next − 14 days. Complements pregnancy and bmi.
Formula
next = last + cycle.
ovulation ≈ next − 14.
How to Use
- Enter the last period date and cycle length.
- The tool gives the next period and ovulation date.
Case Studies
Last 2026-08-01, cycle 28 → next 08-29, ovulation 08-15
08-01 + 28 = 08-29; minus 14 = 08-15.
FAQ
Is it accurate?
It is an estimate; individual variation is large.
How is it different from pregnancy?
Pregnancy estimates due date from LMP; this estimates the cycle.
What is it used for?
Period tracking.
How precise?
To the date.
Related Tools
References
Content review: Calculatorism Science Team. Results are for reference only; please refer to the relevant authorities for the official figures.