CalculatorsSleep, cycle and pregnancyDue date calculator
Due date calculator
Estimate your due date from your last period, your conception date or an IVF transfer, and see how far along you are today.
Put in your numbers, and your result appears here.
How a due date is worked out
Pregnancy is counted from the first day of your last period, not from conception, so it runs about 280 days, or 40 weeks. That assumes a 28-day cycle, so we move the date for a longer or shorter one.
From a known conception date it's 266 days. After IVF, the embryo's age sets it: 261 days from a day 5 transfer, or 263 from a day 3.
What can change it
An early ultrasound is the most accurate way to date a pregnancy. If it disagrees with your period date by more than a small margin, doctors go by the scan.
A due date is a middle point, not a deadline. Most babies arrive within a couple of weeks either side, and few on the day itself.
Questions
Why am I already 2 weeks pregnant at conception?
The count starts at your last period, around two weeks before you ovulate, because that date is easier to know than conception.
My cycles are irregular. Will this work?
Not as well, because it can't tell when you ovulated. An early ultrasound will give you a much better date.
When does each trimester start?
The second starts at 14 weeks, and the third at 28 weeks. Your results show these as dates.
Do you store my dates?
No. They stay in this browser tab. They're not sent to us, saved or put in the address bar.
Sources
Written by LifeFrom from the sources above, and not yet reviewed by a clinician. An estimate for your own understanding: it doesn't diagnose or treat anything, and it doesn't replace your doctor.
