This estimate uses Naegele’s rule (280 days from the last menstrual period). Change the date or your cycle length above, or open the full due date calculator to calculate from a known due date or conception date instead.
Due date if your last period was Saturday, September 13, 2025
If the first day of your last period was Saturday, September 13, 2025, your estimated due date is Saturday, June 20, 2026 — 40 weeks later.
First day of your last menstrual period (how doctors date a pregnancy)
⚕️ This is an estimate based on Naegele’s rule (40 weeks from your last period). Only about 1 in 20 babies arrive on the exact due date. Always confirm with your doctor or midwife.
FAQ
What is my due date if my last period was Saturday, September 13, 2025?
Counting 40 weeks (280 days) from Saturday, September 13, 2025, your estimated due date is Saturday, June 20, 2026. This assumes a 28-day cycle — adjust your cycle length in the calculator if it differs.
How many weeks pregnant does that make me?
As of today, that is about 40 weeks — trimester 3.
How accurate is this estimate?
It is an estimate — only about 1 in 20 babies arrive on the exact due date. Confirm with your doctor or midwife and an early scan.
Medical disclaimer. Estimates only, not medical advice — always confirm your due date with a healthcare professional.
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