Health
Pregnancy Due Date
Estimate a baby’s due date from the last menstrual period (LMP) and track trimester milestones with a cycle-length adjustment.
Naegle’s rule with cycle-length adjustment and milestone checkpoints.
Naegle’s rule with cycle offset
Due date = LMP + 280 days + (cycle length − 28)
The tool maps Naegele’s rule to your specific cycle. It also projects second trimester (13 weeks) and viability (24 weeks) checkpoints from the same starting date.
How to use
- Select the LMP date on the calendar input.
- Enter your average cycle length (default 28 days).
- Review the due date, weeks along as of today, trimester stage, and milestone dates.
Example
Input: LMP = 15 Jan 2024, Cycle length = 28 days
Output: Estimated due date = 21 Oct 2024, Second trimester begins = 15 Apr 2024, Viability (24 weeks) = 1 Jul 2024
Student-friendly breakdown
This walkthrough emphasizes the most searched ideas for Pregnancy Due Date: pregnancy due date calculator, pregnancy calculator, due date calculator, pregnancy week calculator. Start with the formula above, then follow the guided steps to double-check your work. For quick revision, highlight the givens, plug into the equation, and finish by verifying your units.
Need more support? Use the links below to open the long-form guide, browse additional examples, or hop into adjacent calculators within the same topic — each one is a quick way to double-check your work or handle a related question without starting from scratch.
Deep dive & study plan
Pregnancy Due Date: LMP-based due date with trimester milestones. It's built around pregnancy, due date, trimester, so you can go from a raw question to a checked answer without switching tools.
The math behind it: The tool maps Naegele’s rule to your specific cycle. It also projects second trimester (13 weeks) and viability (24 weeks) checkpoints from the same starting date. The core relationship is Due date = LMP + 280 days + (cycle length − 28), shown above the calculator so you can see exactly how your inputs turn into the result.
To use it well: (1) Select the LMP date on the calendar input. (2) Enter your average cycle length (default 28 days). (3) Review the due date, weeks along as of today, trimester stage, and milestone dates. Keep your units consistent as you go, and re-run a case you already know the answer to — it's the fastest way to catch a typo before it throws off a result you're relying on.
Worked example: entering LMP = 15 Jan 2024, Cycle length = 28 days returns Estimated due date = 21 Oct 2024, Second trimester begins = 15 Apr 2024, Viability (24 weeks) = 1 Jul 2024. Try swapping in your own numbers next, especially a case you're unsure about, before you use this for something that matters.
Quick retention checklist
- Speak the formula aloud (or annotate it) so the relationships stick.
- Write each step in your own words and compare with the numbered list above.
- Swap in new numbers for the Example to make sure the calculator (and your logic) handles edge cases.
- Check at least one related calculator below — it's the fastest way to confirm your numbers still line up from a different angle.
FAQ & notes
What if my cycles are irregular?
Use your best average. For significantly irregular cycles, confirm timelines with an ultrasound for maximum accuracy.
Does this replace medical advice?
No. The calculator offers an educational estimate and should be validated with your healthcare provider.
What formula does the Pregnancy Due Date use?
The tool maps Naegele’s rule to your specific cycle. It also projects second trimester (13 weeks) and viability (24 weeks) checkpoints from the same starting date.
How do I use the Pregnancy Due Date?
Select the LMP date on the calendar input. Enter your average cycle length (default 28 days). Review the due date, weeks along as of today, trimester stage, and milestone dates.