Ovulation Due Date Calculator
Track your ovulation? Enter the date you ovulated to get a more accurate due date — especially helpful for irregular cycles.
Calculate Due Date from Ovulation
Enter the date you ovulated (detected via OPK, BBT, or ultrasound) to calculate your estimated due date.
Conception typically occurs within 24 hours of ovulation. Ovulation and conception dates are treated as equivalent.
Why Use Ovulation for Due Date Calculation?
The standard LMP method assumes everyone ovulates on day 14 of a 28-day cycle. In reality, ovulation varies considerably — some women ovulate as early as day 10, others as late as day 21 or beyond. Using your actual ovulation date eliminates this assumption and gives you a more precise due date estimate. This is especially important if you have longer cycles (PCOS, for example, often delays ovulation) or shorter cycles.
The formula is identical to the conception calculator: EDD = Ovulation Date + 266 days. This reflects the 266-day average from fertilization to full-term delivery. The result is the same due date you’d get if you entered your ovulation date as your conception date.
How to Track Ovulation Accurately
Detects LH surge 24–36 hours before ovulation. Most convenient home method.
Temperature rises 0.2°C after ovulation. Confirms ovulation has occurred.
Clear, stretchy 'egg-white' mucus signals peak fertility approaching ovulation.
Follicle tracking by a clinician is the most precise ovulation detection method.
When Your Due Date Might Be Adjusted
Even with known ovulation timing, your provider may adjust your estimated due date after an early ultrasound if fetal measurements differ significantly from expected growth. This is common and helps standardize care decisions such as genetic screening windows, anatomy scan timing, and when to monitor for post-term pregnancy.
Most pregnancies do not deliver exactly on the due date. Use the result as a planning anchor for appointments, leave planning, and milestone tracking, while remembering that normal full-term birth can occur across a range of dates near your estimated due date.
Frequently Asked Questions
Common questions answered by our medical team