Pregnancy Due Date Calculator – Estimate Your Due Date | Medwell Guide

Free Pregnancy Calculator

Pregnancy Due Date Calculator

Estimate your baby’s expected due date in a few simple steps. Enter the first day of your last period, your conception date, or your IVF transfer date to see your estimated due date and how far along you may be.

  • Three methods: due date by LMP, conception date, or IVF transfer.
  • Clear results: estimated due date, weeks pregnant, and key milestones.
  • Private: calculations run in your browser. Nothing you enter is stored or sent.

Calculate your estimated due date

Choose a method and enter your details.

Calculation method

Usually 28 days. Enter a number from 20 to 45.

Your information stays on your device.

Simple steps

How to Use the Pregnancy Calculator

Getting your estimated due date takes less than a minute.

  1. Select your calculation method

    Choose last menstrual period (LMP), conception date, or IVF transfer date, depending on what you know.

  2. Enter your date and details

    Add the requested date, plus your average cycle length or embryo age if you’re using those methods.

  3. View your estimated due date

    See your estimated due date, how many weeks along you may be, and key dates in your pregnancy timeline.

The method

How Is the Due Date Calculated?

The standard way to estimate a due date is to count 40 weeks (280 days) from the first day of your last menstrual period. This is often called the due date by LMP, and it assumes a 28-day cycle with ovulation around day 14.

If your cycles are usually longer or shorter than 28 days, the estimate is adjusted by the difference. When the conception or IVF transfer date is known, the estimate is counted from that date instead.

Every pregnancy is different, and its length naturally varies. An early ultrasound or your healthcare provider can give a more accurate estimated due date based on your baby’s measurements.

Good to know: pregnancy weeks are counted from the first day of your last period, about two weeks before conception usually happens.

By last menstrual period

LMP + 280 days + (cycle length − 28 days)

The most common method. For a 28-day cycle, this is simply 40 weeks after your LMP.

By conception date

Conception date + 266 days

Conception usually happens about two weeks after the start of the last period, so 38 weeks are added.

By IVF transfer date

Transfer date + (266 days − embryo age)

For a 5-day embryo, that’s 261 days after transfer. For a 3-day embryo, 263 days.

Week by week

Your Pregnancy Timeline

A general overview of the three trimesters. Every pregnancy is unique, so your care team’s guidance comes first.

  1. Weeks 1–13

    First trimester

    Early development begins. Tiredness or nausea are common. It’s a good time to book your first prenatal appointment.

  2. Weeks 14–27

    Second trimester

    Many people feel more energetic. An anatomy scan is often offered around 18–22 weeks, and you may start to feel movement.

  3. Weeks 28–40

    Third trimester

    Your baby keeps growing and gaining weight. Prenatal visits usually become more frequent as you prepare for birth.

  4. Around week 40

    Estimated due date

    Only a small share of babies arrive exactly on their due date. Birth anytime from 37 to 42 weeks is common.

Questions

Frequently Asked Questions

How accurate is a pregnancy due date calculator?

A pregnancy due date calculator gives a helpful estimate using standard calculations. How close it is depends on how sure you are of your dates and how regular your cycles are. An early ultrasound is generally considered the most accurate way to date a pregnancy, so your healthcare provider may adjust the date.

What if I don’t remember my last period?

If you know your approximate conception date or IVF transfer date, you can use those methods instead. If not, your doctor or midwife can estimate how far along you are, usually with an ultrasound.

Can my due date change after an ultrasound?

Yes. If an early ultrasound measurement differs noticeably from the date based on your last period, your provider may update your estimated due date. Once a due date is set early in pregnancy, it usually isn’t changed later.

How many weeks is a typical pregnancy?

A typical pregnancy is about 40 weeks (280 days) counted from the first day of the last menstrual period, which is roughly 38 weeks from conception. Babies born from 39 weeks to 40 weeks and 6 days are considered full term.

Is the calculated due date guaranteed?

No. The estimated due date is a guide, not a guarantee. Many babies are born in the weeks before or after it, and only a small share arrive on the exact day. Your care team will help you understand what’s expected for your pregnancy.

Health Disclaimer

This Pregnancy Due Date Calculator provides educational estimates only. It does not diagnose or confirm pregnancy, and it does not replace advice from a doctor, midwife, or other qualified healthcare professional.

If you are pregnant or think you may be, please speak with a healthcare provider about your care. For IVF pregnancies, confirm your due date with your treating fertility clinic.