# Due Date Calculator | Clever Mum

> Work out your estimated due date from your last period (with adjustable cycle length), plus your trimester dates and key milestone weeks.

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# Due Date Calculator

    
 
Quick answer — How does the due date calculator work? 

 
Enter the first day of your last menstrual period and your average cycle length; the calculator applies the standard method used by UK midwives (280 days from LMP, adjusted for cycle) to estimate your due date. Your dating scan gives the definitive date.

    First day of your last periodAverage cycle length: 28 days
Estimates use the standard 280-day method adjusted for your cycle length. Your dating scan (around 12 weeks) gives the definitive due date — and only around 1 in 20 babies arrive on the day itself. This tool is general information, not medical advice.