Health Calculator

Free Pregnancy Due Date Calculator — EDD & Gestational Weeks

Calculate your estimated pregnancy due date (EDD) and current gestational age based on your last menstrual period with our free pregnancy calculator.

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Pregnancy Calculator — Interactive Tool

Enter your values below for instant, high-precision results

What is the Pregnancy Calculator?

The Pregnancy Calculator from SmartCalc is a precision-engineered computing utility designed to solve calculations instantly, accurately, and without requiring any personal data or account signups. Whether you are analyzing mathematical equations, evaluating financial investments, checking health metrics, or converting international units, this tool provides real-time computational accuracy directly inside your browser.

How to Use the Pregnancy Calculator — Step-by-Step

Follow these quick steps to calculate your results immediately:

  1. 1
    Enter the first day of your Last Menstrual Period (LMP) into the calendar box.
  2. 2
    Click 'Calculate Due Date' to run the pregnancy progress tracking algorithm.
  3. 3
    Review the estimated delivery date, current gestational age, and trimester milestones.

Naegele's Obstetric Rule

All calculations are computed based on mathematically rigorous standards and formulas:

Mathematical Formula Due Date = First day of LMP + 1 Year − 3 Months + 7 Days (or LMP + 280 Days)

Worked Example

First day of Last Menstrual Period: January 15th:
1. Add 7 days: January 22nd
2. Subtract 3 months: October 22nd
3. Estimated Delivery Date (EDD) = October 22nd

Reference Data & Key Standards

Trimester StageGestational WeeksKey Developmental Highlights
First TrimesterWeeks 1 to 13Embryo implantation, heart development, organ formation
Second TrimesterWeeks 14 to 27Fetal movement felt, anatomy scan, rapid skeletal growth
Third TrimesterWeeks 28 to 40+Lung maturation, rapid weight gain, preparation for delivery

Practical Tips & Best Practices

💡 Pro Tips:

  • Only about 4%–5% of babies arrive on their exact predicted due date; delivery within 2 weeks before or after is completely normal.
  • Gestational age is measured from the first day of your last period, which is approximately 2 weeks before conception occurs.
  • Early ultrasound scans (dating scans) between weeks 8 and 12 provide the most precise medical confirmation of due dates.

Frequently Asked Questions

We use Naegele's rule: add 280 days (40 weeks) to the first day of your last menstrual period (LMP) to estimate the due date.

Gestational age measures the progress of pregnancy in weeks and days, starting from the first day of your last menstrual period (LMP).

Yes. Ultrasounds performed during the first trimester provide the most accurate measurements and may adjust the EDD set by your LMP.

Key Takeaways
  • Computes Estimated Date of Delivery (EDD) using standard Naegele's obstetric rule.
  • Tracks current gestational week, days, and trimester status.
  • Highlights key developmental milestones throughout the 40-week gestation journey.
  • Privacy-first: zero personal health information is collected or stored.