Free Pregnancy Due Date Calculator
Estimate your due date and how far along you are.
What is the Pregnancy Due Date Calculator?
One of the first questions after a positive test is simply: when? A due date turns an abstract nine months into a real date on the calendar to plan and prepare around.
This due date calculator estimates when your baby is likely to arrive, and how far along you are right now, using the same standard rules clinicians start with.
Last updated: Aug 14, 2026
What does this tool do?
You enter the first day of your last period (or a known conception date) and your cycle length, and it estimates your due date.
It also shows how many weeks and days along you are today and which trimester you're in, plus an estimated conception date.
Key features
Due date estimate
From last period or conception.
How far along
Current weeks, days and trimester.
Cycle adjustment
Accounts for your cycle length.
Conception estimate
Approximate date of conception.
Private
Runs in your browser; nothing stored.
Example
Common use cases
- Expectant parents — Plan for the arrival.
- Partners & family — Follow the pregnancy timeline.
- Anyone who's just found out — Get a first estimate.
- People tracking cycles — See how dates line up.
- Planners — Book leave and appointments.
- The curious — Understand the milestones.
- Those between scans — Have a working estimate.
- Anyone preparing — Count down the weeks.
Benefits
- It turns a positive test into a real date.
- It shows how far along you are, not just the end date.
- It adjusts for cycle length for a better estimate.
- It keeps everything private on your device.
Tips
- Use the first day of your last period for the standard estimate.
- Enter your real average cycle length if it isn't 28 days.
- An early ultrasound often refines or replaces this date.
- Remember a full-term birth is anywhere from 37 to 42 weeks.
- Track symptoms and appointments against the weeks along.
- Due dates shift — treat it as a window, not a deadline.
- Share the estimate with your care provider to confirm.
- Re-check after any dating scan updates your timeline.
Common mistakes to avoid
Treating the due date as exact
Fix: It's an estimate; only about 1 in 20 babies arrive on it. Think of a two-week window.
Ignoring cycle length
Fix: A longer or shorter cycle shifts the date — enter your real average.
Using it as medical advice
Fix: It's informational; your doctor or midwife and an ultrasound give accurate dating.
Confusing last period with conception
Fix: Pick the matching method; conception is usually about two weeks after the last period starts.
How it works
- 1
Pick a method
Last period or conception date.
- 2
Enter the date
And your cycle length.
- 3
See your estimate
Due date, weeks and trimester.
Frequently asked questions
From your last menstrual period using the standard 280-day (40-week) rule, adjusted for your cycle length — or 266 days from a conception date.
It's an estimate. Only about 1 in 20 babies arrive exactly on the due date; an ultrasound and your doctor give the most accurate dating.
From your last menstrual period using the standard 280-day (40-week) rule, adjusted for your cycle length — or 266 days from a conception date.
It's an estimate. Only about 1 in 20 babies arrive exactly on the due date; an ultrasound and your care provider give the most accurate dating.
Enter your real average cycle length and the estimate adjusts accordingly.
A pregnancy is generally considered full term from 37 to 42 weeks, so births around the due date are all normal.
No. It's an informational estimate — always confirm with your doctor or midwife.
No. Everything is calculated in your browser and nothing is saved.
Conclusion
A due date calculator gives you a first, friendly estimate of when your baby will arrive and where you are in the journey. Confirm the date with your care provider, and use the countdown timer to count down the weeks.