Pregnancy Due Date Calculator
Calculate your pregnancy due date from your last menstrual period or conception date. See your current week, trimester, days remaining, and key milestones through your pregnancy.
About the Pregnancy Due Date Calculator
The Pregnancy Due Date Calculator on ToolHaven is a free, browser-based tool that helps you calculate your pregnancy due date from your last menstrual period or conception date. See your current week, trimester, days remaining, and key milestones through your pregnancy. It runs entirely in your browser, so no data is sent to any server, and no account or signup is required. Whether you are a student, professional, or just someone looking for a quick answer, this tool gives you accurate results in seconds.
How to use the Pregnancy Due Date Calculator
Using this tool is straightforward. Choose whether you know your last menstrual period (LMP) date or your conception date. Enter the date and click Calculate. You'll see your due date, how many weeks along you are, which trimester you're in, and key milestones.
Results are updated instantly as you enter values, so there is no need to click a submit button. You can adjust inputs freely and compare different scenarios in real time.
Why use ToolHaven?
ToolHaven offers 178+ free online calculators and tools across categories including Finance, Health, Math, Education, and more. All tools are free to use, require no installation, and work on any device. Your inputs never leave your browser, so your data stays private. The Pregnancy Due Date Calculator is part of our Health collection. Explore related tools in the sidebar to get more done in one place.
How to use
- Choose whether you know your last menstrual period (LMP) date or your conception date.
- Enter the date and click Calculate.
- You'll see your due date, how many weeks along you are, which trimester you're in, and key milestones.
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Pregnancy due dates are calculated based on Naegele's rule: add 280 days (40 weeks) to the first day of your last menstrual period (LMP). This assumes a regular 28-day cycle with ovulation on day 14. If you know your conception date instead, the calculator adds 266 days (38 weeks) to get the due date.
Only about 5% of babies are born exactly on their due date. Most arrive within 2 weeks on either side. Full-term pregnancy is considered 39-40 weeks. Babies born at 37-38 weeks are 'early term', while those born at 41-42 weeks are 'late term'.
Frequently Asked Questions
How accurate is the due date?
The LMP-based due date is an estimate. Accuracy depends on having regular cycles and knowing your LMP date precisely. An early ultrasound (before 12 weeks) gives a more accurate due date and is often used to confirm or adjust the LMP estimate.
What if my cycles are irregular?
Naegele's rule assumes a 28-day cycle. Longer or shorter cycles affect when ovulation occurs, which shifts the due date. If your cycles are irregular, an ultrasound date is more reliable than the LMP calculation.
When does each trimester start and end?
First trimester: weeks 1-12. Second trimester: weeks 13-26. Third trimester: weeks 27-40. The end of the first trimester (around week 12) is when the risk of miscarriage drops significantly.
What does 'weeks pregnant' mean?
Pregnancy weeks are counted from the first day of your last period, not from conception. So you're actually '2 weeks pregnant' before you even conceive. At the time of a missed period, most women are about 4 weeks pregnant by this counting method.