Pregnancy Calculator

Calculate your estimated due date, current week of pregnancy, trimester, and key milestones. Enter the first day of your last menstrual period (LMP) or your conception date for a complete pregnancy timeline.

Due Date Calculator

How Due Date is Calculated

Naegele's Rule (from LMP): Due Date = LMP + 280 days (40 weeks) From conception date: Due Date = Conception + 266 days (38 weeks) Trimester boundaries: 1st Trimester: Weeks 1–13 2nd Trimester: Weeks 14–26 3rd Trimester: Weeks 27–40

Pregnancy Milestones

WeekMilestone
Week 4Missed period, home test positive
Week 8Heartbeat detectable by ultrasound
Week 12End of 1st trimester, NT scan
Week 20Anatomy scan / gender ultrasound
Week 24Viability milestone
Week 283rd trimester begins
Week 37Full term
Week 40Due date

Frequently Asked Questions

How accurate is an estimated due date?+
Only about 5% of babies are born on their exact due date. The due date is an estimate — most babies arrive within 2 weeks before or after. An early ultrasound (before 14 weeks) is the most accurate way to confirm gestational age.
What is the LMP method?+
The LMP (Last Menstrual Period) method calculates due date by adding 280 days (40 weeks) to the first day of your last period. This is the standard method used by most healthcare providers, based on Naegele's Rule from 1850.

About the Pregnancy Calculator

This free pregnancy calculator helps you get accurate results instantly without needing to work through the math manually. Whether you need a quick estimate or a precise figure, having a reliable tool on hand saves time and reduces errors compared to manual calculation.

How to Use This Calculator

  1. Enter your values in the input fields above. Each field is labeled to guide you.
  2. Double-check your inputs — results are only as accurate as the numbers you enter.
  3. Click the Calculate button to see your result instantly.
  4. Use the result for your planning, budgeting, or decision-making.

Why Accurate Calculations Matter

Small errors in math calculations can compound into significant problems. A 1% miscalculation in a budget or measurement can translate to hundreds or thousands of dollars in wasted resources, or result in having to redo work entirely. This calculator uses the standard formulas and methods to give you reliable results you can trust.

Tips for Getting the Best Results

Frequently Asked Questions

Is this calculator free? Yes — completely free with no account, login, or payment required. Use it as many times as you need.

How accurate are the results? This calculator uses the standard formulas for pregnancy calculations. Results are accurate for typical use cases. For specialized or high-stakes applications, consult a professional.

Does it work on mobile? Yes. This calculator is fully responsive and works on smartphones, tablets, and desktops.