🤰Pregnancy / Due Date Calculator
Estimate due date, current pregnancy week, and trimester from last menstrual period (LMP) or conception date — based on Naegele's rule. Useful for a rough first estimate before your first OB visit, tracking weekly changes, and planning for delivery.
How to use
- 1Pick the reference mode (LMP / conception).
- 2Enter the date — due date and weeks are calculated.
FAQ
Is it accurate?+
It's an estimate based on Naegele's rule (LMP + 280 days). About 70% of births fall within ±2 weeks of the predicted date. Follow your OB's ultrasound dating for accuracy.
What if I don't know my LMP?+
Use the conception (ovulation) date, or work backwards from ultrasound dating. Your first OB visit will confirm precisely.
How are weeks counted?+
LMP is counted as week 0, day 0. Actual conception is ~2 weeks later, but pregnancy weeks are standardized to LMP. 40 weeks = 9 full months.
How are trimesters split?+
1st: 0–13 weeks, 2nd: 14–27 weeks, 3rd: 28–40 weeks. Each has different bodily changes and considerations.
Same formula for twins?+
Twins often deliver at 36–37 weeks, so estimates may differ. Follow your OB's guidance.
Is this medical advice?+
This is a calculator only. It doesn't replace medical advice or diagnosis — always consult a healthcare provider.