Estimate your delivery date and current week from your last period.
🛠️ Free tool by the NayaPakistan team · Updated September 2026
This calculator estimates your expected delivery date (EDD) using Naegele's rule — adding 280 days (40 weeks) to the first day of your last menstrual period (LMP). It also shows how many weeks and days along you are now, and which trimester you are in.
Pregnancy is counted in three trimesters — roughly weeks 1–12, 13–26 and 27–40. Conception usually happens about two weeks after the LMP. Only around 1 in 20 babies actually arrives on the estimated date, and an early dating ultrasound is more accurate than the LMP method, especially for irregular cycles — so treat this as a guide and follow the date your doctor confirms.
By Naegele's rule: add 280 days (40 weeks) to the first day of your last menstrual period. This calculator does that and also shows your current week and trimester.
Enter the first day of your last period and the tool counts the weeks and days since then, which is how pregnancy weeks are measured.
It is an estimate — only about 1 baby in 20 arrives exactly on the date. An early dating ultrasound is more accurate, particularly with irregular cycles.
The first trimester is roughly weeks 1–12, the second weeks 13–26, and the third weeks 27–40. The calculator shows which one you are currently in.