Pregnancy Due Date Calculator
Estimate a due date from your last period and cycle length, or keep the date your clinician gave you.
For information and personal records. Estimates may be inaccurate. Seek individual care when needed.
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What this can tell you
- Estimate a due date and how many weeks and days pregnant you are on a chosen date.
- Keep a clinician-provided due date, which takes precedence.
What it cannot tell you
It cannot date a pregnancy as accurately as a dating scan, and it does not calculate dates for IVF. It does not tell you whether a pregnancy is healthy.
How this is calculated
Estimated due date = first day of last period + 280 days + (cycle length − 28) days. Weeks pregnant on a date = 280 − days remaining until the due date, shown as completed weeks + days. Trimester convention: first up to 13+6, second 14+0 to 27+6, third from 28+0.
Related InfantXmore articles
Sources
- Due date calculator; Baby due dates and how it affects my care – NHS; Royal Berkshire NHS FT, England. Checked 19 October 2026 (official entry point). Opens in a new tab.
- Week-by-week guide to pregnancy – NHS Best Start in Life, England. Checked 19 October 2026 (official entry point). Opens in a new tab.
Group: Fertility & reproductive health. Responsible: InfantXmore editorial team (not a clinical review). No clinician endorsement is claimed.
Your data
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