Pregnancy Calculator
First day of your last menstrual period
Default is 28 days. Typical range: 20-40 days.
How It Works
- Due Date: Calculated using Naegele's Rule (LMP + 280 days), adjusted for your cycle length
- Conception Date: Estimated as cycle length - 14 days from LMP
- Fertile Window: Typically 5 days before conception to 1 day after
- Gestational Age: Measured from the first day of your last menstrual period
- Trimester: 1st (0-13 weeks), 2nd (14-27 weeks), 3rd (28+ weeks)
Overview
Calculate your estimated due date using your last menstrual period (LMP) and cycle length. This pregnancy calculator provides your estimated due date, current pregnancy week, trimester, estimated conception date, and a typical fertile window. Based on Naegele's Rule, the standard medical formula used by healthcare providers worldwide, this calculator offers quick and reliable results for early pregnancy tracking. Perfect for expecting parents who want an easy way to understand their pregnancy timeline without signing up or sharing personal data. All calculations are done privately in your browser and never stored. Whether you're newly pregnant or tracking your progress, this tool gives a clear overview of your pregnancy schedule, including helpful milestones like the end of the first trimester and your anatomy scan date.
About
About Pregnancy Calculator
Calculate your estimated due date using your last menstrual period (LMP) and cycle length. Get estimated conception date, pregnancy week, trimester, and key milestones.
Features:
- Calculate due date instantly
- Naegele's Rule formula
- Cycle length customization
- Gestational age tracking
- Trimester identification
- Conception date estimation
- Fertile window calculation
- Key milestone dates
- 100% private - no data stored
FAQ
How accurate is the due date?
The calculator provides an estimate based on Naegele's Rule. Ultrasound dating is more precise, especially early in pregnancy. Only about 5% of babies are born exactly on their due date.
What if my cycle isn't 28 days?
Adjust the cycle length for a more personalized due date. The calculator adds or subtracts days based on the difference from the standard 28-day cycle.
Can I calculate without knowing my LMP?
This calculator requires LMP. If unknown, use an ultrasound-based estimate or consult with your healthcare provider.
What is gestational age?
Gestational age is measured from the first day of your last menstrual period, not from conception. This is the standard medical measurement.
Are results private?
Yes. All calculations stay entirely on your device. We don't collect, store, or transmit any personal data.
What if my gestational age seems wrong?
Verify your LMP date is correct. If you're unsure, an ultrasound can provide a more accurate dating.