Pregnancy Calculator

Estimate your due date, conception date, and current week of pregnancy. Free online pregnancy calculator.

What is Pregnancy Calculator?

A pregnancy calculator estimates your due date and tracks important milestones throughout your pregnancy journey. Whether you've just discovered you're expecting or you're planning ahead, this calculator helps you understand where you are in your pregnancy and what to expect in the coming weeks.

Pregnancy is typically calculated as 40 weeks (280 days) from the first day of your last menstrual period (LMP), not from the date of conception. This is because the exact date of conception is often unknown, but most women can recall when their last period started. The calculator also shows your current trimester, weeks pregnant, and key developmental milestones for your baby.

Formula

Due Date = First day of LMP + 280 days (40 weeks)

Alternatively: Due Date = LMP + 7 days - 3 months + 1 year (Naegele's Rule)

Conception date is typically ~2 weeks after LMP

Trimester 1: Weeks 1-12

Trimester 2: Weeks 13-27

Trimester 3: Weeks 28-40+

How to Calculate

Enter the first day of your last menstrual period.
Alternatively, enter your estimated conception date.
View your estimated due date.
Check your current week of pregnancy and trimester.
See key milestones and developmental stages.

Example

If your last menstrual period started on March 1, 2025, your estimated due date is December 5, 2025 (March 1 + 280 days). On June 1, 2025, you would be approximately 13 weeks pregnant, entering your second trimester. Your conception likely occurred around March 15, 2025.

Key Benefits

Get accurate pregnancy calculator results instantly
Save time with pregnancy calculator calculations
Make informed decisions with clear data
Free on any device no downloads

Common Mistakes to Avoid

Using inaccurate inputs
Ignoring key factors
Misinterpreting outputs

Pro Tips

Double-check inputs for accuracy
Run multiple scenarios
Combine with other tools

Key Terms Explained

Input: Values you provide
Output: Results computed
Formula: Method used
Result: Calculated answer

When to Use This Calculator

For quick pregnancy calculator
Comparing pregnancy calculator options
Understanding pregnancy calculator impact

Common Use Cases

Estimating your baby's due date
Tracking pregnancy progress week by week
Planning maternity leave and baby preparations
Understanding developmental milestones during pregnancy

Frequently Asked Questions

How accurate is the due date calculation?

Only about 5% of babies are born on their exact due date. Most deliveries occur between 37-42 weeks. The due date is an estimate, and your healthcare provider may adjust it based on ultrasound measurements.

Why is pregnancy counted from the last period?

Most women know when their period started but not when conception occurred. Counting from the LMP provides a consistent starting point, even though conception typically happens about 2 weeks later.

What if I have irregular cycles?

With irregular cycles, the LMP-based calculation may be less accurate. An early ultrasound (8-12 weeks) provides a more reliable due date estimate. Consult your healthcare provider for personalized guidance.

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