Pregnancy Due Date Calculator
Estimate your due date from your last period, conception date, or IVF transfer date, and see your gestational age, trimester, and days to go.
Pregnancy Due Date Calculator estimates your due date from the first day of your last period, a known conception date, or an IVF embryo transfer date. It shows your current gestational age in weeks and days, your trimester, and how many days are left until your due date. Runs entirely in your browser — no upload, no signup. Made by FreeToolHub.
Enter the first day of your last menstrual period.
Please enter a valid date.
How it works
Pick the method that matches what you know: the first day of your last period, a known conception date, or an IVF embryo transfer date. The calculator converts your input to an equivalent last-period date, then adds 280 days (40 weeks) — the standard obstetric estimate known as Naegele's rule — to get your due date. It also compares today's date to that timeline to show your current gestational age in weeks and days, which trimester you're in, and how many days are left.
Frequently Asked Questions
How is my due date calculated?
By default this calculator uses Naegele's rule: it adds 280 days (40 weeks) to the first day of your last menstrual period (LMP). If you enter a conception date or an IVF transfer date instead, it works out an equivalent LMP first, then adds the same 280 days, so every method lands on a consistent due date.
I don't know my exact LMP — can I use my conception date instead?
Yes. Switch to the Conception date option and enter the date you believe conception occurred. The calculator assumes ovulation and conception happened 14 days after LMP in an average cycle, converts your date accordingly, and estimates the same due date.
How does this work for an IVF pregnancy?
IVF due dates are usually the most precise since the transfer date is exactly known. Choose 3-day transfer or 5-day (blastocyst) transfer, enter your transfer date, and the calculator adds 263 or 261 days respectively — the standard offsets fertility clinics use, both equivalent to 280 days from an estimated LMP.
What are the three trimesters?
The first trimester runs from week 1 through week 12, the second from week 13 through week 27, and the third from week 28 until birth, around week 40. This calculator marks which trimester you're in based on your gestational age.
Why might my actual delivery date be different?
Only about 1 in 20 babies are born on their exact estimated due date. Cycle length varies between people, ovulation doesn't always happen exactly on day 14, and every pregnancy progresses differently, so this date is a well-informed estimate, not a guarantee.
Is this medical advice?
No. This tool provides a general estimate based on standard obstetric dating conventions, not a diagnosis or personalized medical guidance. Your doctor or midwife may adjust your due date using an ultrasound measurement, which can be more accurate than dates alone.