OhMyCalc

Pregnancy & Conception Calculator

Calculate your conception date, due date, and trimester endpoints from your last period date.

How to Use the Pregnancy & Conception Calculator

  1. Enter the date of your last menstrual period.
  2. Click Calculate to compute your conception date, due date, and trimester end dates.
  3. Review the full pregnancy timeline including all three trimester milestones.
  4. Use the dates to plan prenatal check-ups and track your pregnancy progress.

Quick Reference

FromTo
1st trimesterWeeks 1–12
2nd trimesterWeeks 13–26
3rd trimesterWeeks 27–40
Due date40 weeks (280 days)
Full term37–42 weeks
Preterm< 37 weeks

Use Cases

Formula

Conception ≈ LMP + 14 days. Due date = LMP + 280 days. Trimesters: 1st ends at 12 weeks, 2nd at 26 weeks.

Frequently Asked Questions

How to use?
Enter your last menstrual period date and click Calculate to see your conception date, due date, and trimester milestones.
Calculation accuracy?
Calculations are performed with high precision.
Is it free?
Yes, all calculators are completely free.