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Pregnancy Calculator – Estimate Due Date Free Online

Estimate your due date and pregnancy week from your last menstrual period date. Free online pregnancy calculator.

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What is Pregnancy Calculator?

A pregnancy calculator estimates your due date and current pregnancy week based on the first day of your last menstrual period (LMP). The standard pregnancy duration is 40 weeks (280 days) from the LMP. This tool provides an estimate — your healthcare provider will confirm your due date with an ultrasound.

How to Use Pregnancy Calculator

  1. 1Enter the first day of your last menstrual period.
  2. 2Your estimated due date and current pregnancy week are calculated instantly.

Key Features

  • ✓Due date calculation from LMP
  • ✓Current pregnancy week and trimester
  • ✓Conception date estimate
  • ✓Key milestone dates

Benefits

  • →Plan for your baby's arrival
  • →Track pregnancy milestones
  • →Prepare for prenatal appointments

Why Use Irreva for Pregnancy Calculator?

Runs 100% in your browser — files never leave your device.
No account, no sign-up, no subscription — free forever.
Works on any device: desktop, tablet, or mobile.
No file size limits from our infrastructure.
Instant results — no server round-trip latency.
Open-source libraries and transparent processing.

Frequently Asked Questions

How is the due date calculated?

The due date is calculated as 280 days (40 weeks) from the first day of your last menstrual period. This is the Naegele's rule method.

How accurate is this calculator?

This is an estimate based on a standard 28-day cycle. Your healthcare provider will confirm your due date with an ultrasound.

What if my cycle is not 28 days?

The standard calculation assumes a 28-day cycle. If your cycle is longer or shorter, your actual due date may differ slightly.

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