Pregnancy Due Date Calculator
Estimates a due date from the first day of the last menstrual period.
Your result
Estimate only. Results update as you type.
How this calculator works
Due date = last period + 280 days, adjusted for cycle length (Naegele’s rule).
Worth knowing
Only about 1 in 20 babies arrive on the due date. An early ultrasound gives a more accurate date.
Guides for this calculator
- Using a Pregnancy Due Date Calculator in Australia: A Step-by-Step Guide
- Common Pregnancy Due Date Mistakes (and a Better Way)
Questions
- Are these calculators medical advice?
- No. They provide general information. See your GP or visit healthdirect.gov.au for personal advice.
- Do they work for children?
- No. Adult formulas are used throughout. Children’s growth is assessed differently.
- Where do the formulas come from?
- Each calculator page names the formula used, such as Mifflin-St Jeor for BMR or the US Navy method for body fat.
This calculator gives general estimates using published Australian rates and formulas. It doesn’t consider your personal circumstances. Check current figures with the ATO, your state government or a qualified professional before making decisions. See our disclaimer.