Ovulation Calculator

Calculates the fertile window, peak fertility days, and expected ovulation timing based on menstrual cycle length.

Pregnancy & Women's Health• Luteal Phase (14 Days Prior to Menses)

Find your most fertile days and estimated ovulation dates for the next 6 cycles.

First Day of Last Period (LMP)

Average Cycle Length (Days)20 – 45 days

days

Estimated Ovulation DaySep 2, 2026Fertile Window: Aug 28, 2026 – Sep 3, 2026

Peak ConceptionSep 1, 2026 & Sep 2, 2026

Next Expected PeriodSep 16, 2026

Evidence-based estimations. Consult a physician for personalized guidance.

Clinical Formula & Calculation Standard

Official clinical definitions and validated mathematical models

Ovulation Day = LMP + (Cycle Length - 14 Days) | Fertile Window = Ovulation - 5 to +1 Day

While the follicular phase varies in duration, the luteal phase (post-ovulation to menses) remains relatively stable at 14 days in healthy cycles.

Human oocytes remain viable for fertilization for 12–24 hours post-ovulation.
Sperm cells survive in fertile cervical mucus for up to 5 days, making the 2–3 days prior to ovulation the highest probability window.

Track pregnancy progress, current week, trimester, and key developmental milestones.

Calculate estimated date of delivery (EDD) based on LMP, conception, or IVF date.

Track healthy weekly weight gain targets during pregnancy based on pre-pregnancy BMI.