Ovulation Calculator
Estimate ovulation and a possible fertile interval from your last period and cycle assumptions.
Formula
Next period=LMP+cycle; ovulation=next period−luteal days; interval=ovulation−5 to +1 days.
First day of last period = 2026-10-01 · Cycle (days) = 28 · Assumed luteal phase (days) = 14
How to use
- Enter the first day of bleeding.
- Set cycle and luteal assumptions.
- Read the estimated dates.
Examples
- 1 Oct 2026, cycle 28, luteal 14 → ovulation around 15 Oct.
Frequently asked questions
Why 14 days?
ACOG describes about 14 days before the next period; actual timing varies.
Can this prevent pregnancy?
No. A calendar prediction cannot confirm ovulation or safe days; irregular cycles reduce reliability.
Is this medical advice?
For reference only; it does not replace a clinician.
Sources
Updated: