Your estimated due date, your exact week and day, and how many weeks are left. No sign-up, no email.
This calculator gives estimates based on Naegele's rule. It is not medical advice. For anything specific, talk to your OB or midwife.
The calculator uses Naegele's rule, the standard your OB uses too: 280 days — 40 weeks — from the first day of your last period. It is an estimate. Only about 5% of babies arrive exactly on the due date; most show up between week 37 and week 42.
If your cycle is not 28 days, the tool adjusts for it. If you have already had a dating ultrasound, calculating from the scan beats calculating from period dates.
If you remember the first day of your last period, use the last-period method — it's the most common one. If you know exactly when conception happened (e.g. after assisted reproduction), use that. If you've already had a dating ultrasound, that calculation is the most reliable.
If your doctor has already given you a due date, you can enter it directly to see how many weeks you are today and how long is left.
First trimester (weeks 1–13): the major organs form. Nausea, exhaustion and food aversions are common. The dating ultrasound usually happens between week 7 and week 12.
Second trimester (weeks 14–27): the steadiest stretch. You start to show, and you feel the first kicks, usually between week 16 and week 22. The anatomy scan lands around week 20 — and this is when most parents build the baby registry, because the shower is coming.
Third trimester (weeks 28–40): the baby puts on weight fast. From week 37 the pregnancy counts as full term. There is no federal paid maternity leave in the United States: FMLA provides unpaid, job-protected leave for employees who qualify, some states run their own paid family leave program, and short-term disability may cover part of it — so your leave start date is a conversation with HR, not a date on a calendar.
The second trimester is the sweet spot. There is still time to compare car seats without panic-buying, you know the sex if you wanted to know, and the shower is close enough that the link has somewhere to go — most hosts want the registry ready before the invitations are mailed.
On BabyWish the registry is free, it holds gifts from any store, guests reserve without signing up, and each gift can only be claimed once, so nobody arrives with the second bouncer. Two minutes to set up, starting from the due date you just calculated.
All free, no sign-up required
