Pregnancy due date
Enter your numbers — the results update instantly.
Estimated due date—
Gestational age—
Trimester1
Worked example
Given: First day of last period = 2026-11-09; Cycle length (days) = 28
Result: Trimester = 1
How it is calculated
1. Enter the values you know. 2. The calculator converts them to base units and applies the formula. 3. The result is shown in the unit you choose.
Frequently asked questions
How do I calculate it?
Given: First day of last period = 2026-11-09; Cycle length (days) = 28. Result: Trimester = 1.
Is the calculator free and private?
Yes. It is free, needs no sign-up and runs in your browser — the numbers you type stay on your device.