Free Pregnancy Due Date Calculator — No Registration Required
The moment you see a positive pregnancy test, one of your first questions is: when is the baby coming? So you open an app, enter your last period date, and it gives you a due date. Then it asks you to create an account to "save your pregnancy journey." Then it offers a weekly subscription for "personalized insights." Then it emails you daily. Then it sells your data to baby product companies. All you wanted was a date.
The Data Problem in Pregnancy Apps
Pregnancy is one of the most aggressively monetized categories in the app economy. The moment a pregnancy app knows your due date, it knows exactly what to sell you: maternity clothes in your second trimester, baby gear in your third, and postpartum products after delivery. Your due date isn't just a date — it's a marketing calendar.
Many pregnancy apps share data with third parties, including advertisers, analytics services, and data brokers. Your estimated due date, combined with your search history and location, creates an advertising profile that follows you through pregnancy and beyond. Some apps have been caught sharing sensitive health data despite claiming otherwise in their privacy policies.
A due date is simple math. You shouldn't have to trade your privacy to calculate it.
How Due Dates Are Calculated
The standard method is Naegele's rule, developed by German obstetrician Franz Naegele in the early 1800s. It works like this: take the first day of your last menstrual period, add 280 days (40 weeks), and you get the estimated due date. The calculation assumes a 28-day cycle with ovulation on day 14. If your cycle is longer or shorter, the estimate shifts accordingly.
An alternative method uses ultrasound measurements. If you've had an early ultrasound (typically between 8 and 14 weeks), the sonographer measures the baby's crown-rump length, which gives a very accurate estimate of gestational age. Our calculator supports both methods — enter your LMP date, or enter the gestational age from your ultrasound report.
The result is an estimate, not a guarantee. Only about 4% of babies are born on their exact due date. Most arrive within two weeks before or after. Use the date as a rough timeline, not a deadline.
What Our Calculator Shows
Beyond the estimated due date, our due date calculator shows several useful milestones:
- Current week of pregnancy. How far along you are right now.
- Days remaining. A countdown to your estimated due date.
- Current trimester. First trimester (weeks 1–13), second (14–26), or third (27–40).
- Conception estimate. The approximate date of conception, calculated as LMP + 14 days.
- Progress bar. A visual indicator of how far along you are, with trimester markers.
Everything runs in your browser. Your date never leaves your device. We store it in your browser's local storage so you can come back and see updated results without re-entering anything. We never see it, never log it, and never share it.
For Partners, Family, and Content Creators
This tool isn't just for expectant mothers. Partners use it to track milestones. Grandparents use it to plan visits. OB-GYNs and midwives embed it on their practice websites so patients can quickly check their dates without installing anything. Parenting bloggers embed it in articles about pregnancy timelines. Baby product brands put it on their sites to keep visitors engaged.
If you run a website in the pregnancy or parenting space, grab the embed code. It's free, lightweight, and adds genuine value to your readers.
Calculate your due date now: Pregnancy Due Date Calculator. No sign-up, no subscription, no data collection. Just the date.