🤰 Due Date Calculator

Estimated due date from last period — plus current week and trimester

days

Your Pregnancy Timeline

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estimated due date
Current Stage—
Trimester—
Days Until Due Date—
⚠️ Only ~4% of babies arrive on their due date — most arrive within 2 weeks either side. Your dating scan (around 12 weeks) gives the most accurate estimate. Always follow your midwife's guidance.

How Due Dates Are Calculated

The standard method (Naegele's rule) adds 280 days (40 weeks) to the first day of your last menstrual period, adjusted for cycle length — for a 31-day cycle, add 3 extra days. From conception date, add 266 days.

Pregnancy Milestones

  • Week 12: dating scan, end of first trimester
  • Week 20: anomaly scan
  • Week 24: viability milestone
  • Week 37: full term begins
  • Week 40: due date

UK Maternity Care

Contact your GP or local midwife service as soon as you know you're pregnant — NHS antenatal care typically begins with a booking appointment at 8–10 weeks. You're entitled to free prescriptions and NHS dental care during pregnancy and for 12 months after birth.