Pregnancy Due Date Calculator

Pick a method. We do the date math and show your estimated due date, current gestational age, trimester, a milestone timeline, and a calendar file you can save.

Overview

There are a few practical ways to estimate a due date, and different clinics may prefer one over another depending on your history and scans. This calculator gives you four options that mirror common workflows: LMP with adjustable cycle length, Conception date, Ultrasound dating using the gestational age shown on the report, and IVF transfer with day-3 or day-5 embryos. You’ll see an estimated due date (EDD), gestational age as of today, the current trimester, and a simple week-by-week milestone table. Everything runs in your browser for speed and privacy.

Use this as a planning helper. It’s useful when comparing dates from different sources, checking how far along you are before an appointment, or adding the EDD to your personal calendar. For more date math, try our Date Calculator. If you’re tracking cycles, the Ovulation Calculator can help estimate fertile windows.

Method

LMP inputs

We adjust EDD by (cycle − 28) days.

How to use this due date calculator

  1. Choose a method. LMP is the classic 40-week count, but if you have a reliable conception date, an early ultrasound report, or an IVF transfer date, pick those instead.
  2. Enter the inputs. For LMP, set your average cycle length so the count reflects cycles longer or shorter than 28 days. For ultrasound, enter the weeks and days shown on the report along with the scan date.
  3. Calculate. The Summary card shows the EDD and gestational age as of today. The badge under it tells you which trimester definition we’re using.
  4. Review milestones. The Timeline card lists common week markers from the implied LMP through week 42, with context relative to today.
  5. Save or share. Export a CSV of the key fields, or create a calendar file (ICS) to add the EDD to your device.

This is an educational estimate and not a medical directive. For personal decisions, work with your clinician.

Understanding your results

Estimated due date (EDD). This is the 40-week anchor for planning. Only a small fraction of births occur on the exact day. Think of it as the midpoint of an expected window rather than a fixed deadline.

Gestational age today. We count completed weeks and extra days. If you switch methods, the EDD and this age can shift slightly because each method anchors the count differently.

Trimester badge. We label trimesters using a clear, widely used split: 0–12w6d, 13–27w6d, and 28w+. Some clinics round these boundaries differently; our labels keep the display simple.

Timeline marks. These are common checkpoints (for example, week 20 for a typical anatomy scan). They’re reminders, not requirements. If your care plan says otherwise, follow that.

FAQ

Why does ultrasound sometimes change the due date?

Early ultrasounds estimate gestational age from measurements. If that estimate differs enough from the LMP-based age, clinicians may re-date the pregnancy. Our ultrasound mode mirrors that approach by subtracting the measured age from 280 days.

How do you handle different cycle lengths?

LMP assumes ovulation about 14 days after the period starts. If your cycle is longer or shorter than 28 days, we offset the EDD by the difference so the count better reflects your pattern.

What is the IVF shortcut you use?

Clinics often use a practical shortcut: add 261 days to a day-5 transfer or 263 to a day-3 transfer to land on an EDD comparable to LMP-based dating.

Can I add the EDD to my calendar?

Yes. Use the “Add EDD to Calendar” button to download an ICS file. It creates an all-day event on the expected date.

Is this medical advice?

No. This is an educational tool. Always rely on your clinician for diagnosis and care decisions.