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ConceiveCalc
Enter your due date — estimate when conception likely occurred.
A typical pregnancy lasts 266 days (38 weeks) from conception, or 280 days (40 weeks) from the last menstrual period (LMP). Subtracting 266 days from the due date gives the estimated conception date. Conception typically occurs around day 14 of the menstrual cycle (ovulation), so LMP is about 2 weeks before conception.
This calculation assumes a standard 28-day cycle with ovulation on day 14. If your cycles are longer or shorter, conception could have occurred earlier or later. Ultrasound dating, especially in the first trimester, is more accurate than LMP-based calculation for establishing gestational age.
Daily energy expenditure with personalised macro splits.
OpenBody mass index with healthy-range guidance.
OpenUS Navy circumference method for body fat percentage.
OpenDaily hydration target based on weight, activity, and climate.
OpenEstimated conception date
March 10, 2026
What you entered
Due date
2026-12-01= December 1, 2026Estimated conception
Due date − 266 days (38 weeks)= March 10, 2026Gestational age (from LMP)
Conception − 14 days to today= 23 weeks, 2 daysResult
Estimated conception date: March 10, 2026
Based on a due date of 2026-12-01, the estimated conception date is March 10, 2026. The current gestational age is approximately 23.285714285714285 weeks.