Pregnancy Calculator

The pregnancy calculator estimates important pregnancy dates, the estimated due date, gestational age (how many weeks pregnant you are), or conception date. Use your last menstrual period, a known conception date, or an existing due date. This MathCalc tool provides quick and easy estimates to help plan appointments and track pregnancy progress.

Pregnancy Calculator

Calculate due date, gestational age, and pregnancy milestones

How to Use
  1. Fill in the Required Values
  2. Click "Calculate" Button
  3. View Step-By-Step Solution

A step-by-step guide on how to use the MathCalc pregnancy calculator

Step by step:

  • Select a calculation type from calculate due date, calculate gestational age, or calculate conception date.
  • Enter the last menstrual period date in the given box.
  • Enter the conception date in the given box.
  • Enter the due date in the given box.
  • Enter the current date in the given box.
  • After entering the values, click on calculate, and in seconds, you will see the result.

Calculate due date

Select “calculate due date” from calculation types. Enter 10/3/2025 in the Last menstrual period box and 23/9/2025 in the current date box.

Step by step:

  • Calculating due date from Last Menstrual Period (LMP)
  • LMP Date: 2025-03-10
  • Estimated conception: 2025-03-24 (LMP + 14 days)
  • Due date: 2025-12-15 (LMP + 280 days)
  • Pregnancy duration: 40 weeks (280 days)

result:

  • Due date: 2026-07-10
  • Conception date: 2025-10-17
  • Weeks pregnant: 40 weeks
  • Days pregnant: 280 days

Example 2: Calculate gestational age

Select “calculate gestational age” from the calculation types. Enter 01/06/2025 in the Last menstrual period box and 23/09/2025 in the current date box.

Step by step:

  • Calculating gestational age
  • LMP Date: 2025-01-06
  • Current Date: 2025-09-28
  • Days since LMP: 265
  • Gestational age: 37 weeks and 6 days
  • Estimated due date: 2025-10-13

result:

  • Gestational age: 37 weeks, 6 days
  • Total days: 265
  • Estimated due date: 2025-10-13
  • Trimester: Third trimester

Example 3: Calculate conception date

Select “calculate conception date” from the calculation types. Enter 30/01/2025 in the due date box and 23/09/2025 in the current date box.

Step by step:

  • Calculating conception date from due date
  • Due Date: 2025-09-28
  • LMP Date: 2024-12-22 (due date - 280 days)
  • Conception Date: 2025-01-05 (LMP + 14 days)

result:

  • Conception date: 2025-01-05
  • LMP date: 2024-12-22
  • Due date: 2025-09-28

Why use the MathCalc pregnancy calculator?

Get quick results: The MathCalc pregnancy calculator can help you determine your due date, gestational age, or conception date in seconds.
Reduce calculation errors: This MathCalc pregnancy calculator utilizes common obstetric formulas (Naegele's rule, LMP counting) to eliminate the need for manual calculations.
Useful for planning: This MathCalc pregnancy calculator helps you schedule prenatal visits and screenings, as well as inform conversations with your healthcare provider.

Pregnancy Calculator FAQs

Is this calculator medically exact?

No, it gives estimates only. For clinical decisions and accurate dating, consult your healthcare provider; an early ultrasound usually provides the most accurate gestational age determination.

What if I don’t remember my LMP?

Give the best estimate you can. The calculator can still use a conception date or an ultrasound date if available. If you are unsure, please consult with your clinician for guidance.

What does a Pregnancy Calculator do?

A Pregnancy Calculator estimates your due date, current pregnancy week, and trimester based on the date of your last menstrual period (LMP). It helps you track your baby’s growth and upcoming milestones easily.

How accurate is the Pregnancy Calculator?

The calculator gives an estimated due date based on a standard 40-week pregnancy cycle. However, every pregnancy is unique, so your doctor’s assessment or ultrasound scan provides the most accurate results.

Can I use this calculator if my menstrual cycle is irregular?

Yes, but the accuracy might vary. If your cycle is irregular, it's best to use the conception date (if known) or consult your healthcare provider for a more precise estimate.

What information do I need to use the Pregnancy Calculator?

You’ll need the first day of your last menstrual period (LMP) and your average cycle length. The calculator will then determine your estimated due date and pregnancy progress.

Can this calculator tell me my baby’s gender or conception date?

No, the Pregnancy Calculator only estimates pregnancy stages and due dates. Gender prediction and exact conception dates should be confirmed through medical testing or ultrasound scans.