What does this tool do?
The Pregnancy Calculator builds your pregnancy timeline from your last menstrual period, estimated conception date, or expected due date. It shows the estimated due date, exactly how many weeks and days along you are, and the key milestones throughout pregnancy in a clear layout for expecting parents.
How to use it
- Enter your values into the fields.
- The result is calculated instantly.
- Read or copy the result.
How the calculation works
Pick one of three input modes: last period, conception, or due date. The tool uses the standard 280-day (40-week) Naegele's rule. From the last menstrual period, conception is estimated around day 14 and birth at day 280. If you enter the conception date instead, the due date is set 266 days later. As soon as you choose a date, cards appear for your last period, conception, due date, and current progress (weeks + days, plus days remaining).
Milestone timeline
The tool lists typical pregnancy milestones from week 6, when a heartbeat may be detectable, through to the expected due date: end of the first trimester at week 12, the anatomy scan and halfway point at week 20, the viability milestone at week 24, end of the second trimester at week 27, and full term approaching at week 36. Stages you've already passed are marked, and each shows its estimated date.
Frequently asked questions
How is the due date calculated?
It adds 280 days (40 weeks) to your last menstrual period, the widely used Naegele's rule. If you enter a conception date, it adds 266 days. This is only an estimate; actual birth often happens a few days before or after.
What if I don't know one of the dates?
Choose whichever mode fits you. Use 'Last period' if you know that date, 'Conception' if you can estimate the day of conception, or 'Due date' if your doctor gave you one; the tool calculates all the other values from your input.
Does this replace medical advice?
No. This calculation is an estimate based on standard averages and is for general information only. For precise dating and health monitoring, rely on ultrasound measurements and your doctor's assessment.
Is Pregnancy Calculator free?
Yes. Pregnancy Calculator and all 300+ tools on MagmaNex are completely free with no signup or account required.
Is my data safe?
Yes. Everything runs locally in your browser. The data you enter is never sent to a server, stored, or shared.
Does it work on mobile?
Yes. Pregnancy Calculator works on phones, tablets and desktops — no app download needed.
🔒 Privacy: everything runs in your browser, your data is never sent to a server.