👶 Due Date Calculator

What is Due Date Calculator?

The Due Date Calculator estimates your pregnancy due date from either the first day of your last menstrual period or your conception date. Choose a method, pick the date, and the tool adds 280 days for LMP dating or 266 days for conception dating to show your estimated due date, then works out how far along you are in weeks and days. It also reports which trimester you are in and lists the milestone dates when each trimester ends. Everything is computed locally in your browser with no account and no data upload.

How to Use Due Date Calculator

1. Choose whether to date from your last menstrual period or your conception date
2. Enter the matching date
3. Read your estimated due date, how far along you are, and the trimester milestones

Why Use Our Due Date Calculator?

• Due date from LMP (plus 280 days) or conception (plus 266 days)
• Current gestational age in weeks and days from today
• Current trimester plus end-of-trimester milestone dates
• Private, in-browser calculation with nothing uploaded

Common Use Cases

• Confirming an estimated due date early in pregnancy
• Tracking weeks and trimester progress at each appointment
• Checking the milestone dates for the end of each trimester

Frequently Asked Questions

• How is my due date calculated?▾
  The most common method adds 280 days (40 weeks) to the first day of your last menstrual period. That assumes a 28-day cycle with ovulation around day 14, which is why a conception-based estimate adds 266 days instead.
• What is the difference between LMP and conception dating?▾
  LMP dating starts from the first day of your last period and is what most clinics use, while conception dating starts from the day you ovulated or conceived. Conception usually happens about two weeks after the LMP, which is why the two methods use 280 and 266 days.
• Is 280 days exact for every pregnancy?▾
  No. 280 days is the average length, and only a small percentage of babies arrive on their exact due date. Treat the date as a best estimate used to plan care, with a couple of weeks either way being normal.