Due Date Calculator
Due date from last period, conception or IVF transfer.
- Gestational age today
- 10 weeks, 0 days
- Days added to your date
- 280
How this calculator works
Each method adds a fixed number of days to a known date: 280 from the last period, 266 from conception, and fewer for IVF transfers because the embryo is already several days old.
Formula
Due date = date + 280 (LMP), 266 (conception), 263 (3-day) or 261 (5-day)
Example
A conception date of January 15, 2026 gives a due date of October 8, 2026.
When to use it
- Dating a pregnancy from IVF records
- Cross-checking an estimated due date
- Planning around key milestones
Frequently asked questions
Which method is most accurate?
IVF transfer dates are the most precise because the embryo's age is known exactly. For natural pregnancies, an early ultrasound is more accurate than dating by the last period.
Can the due date change?
Yes. Providers often adjust it after the first-trimester ultrasound if the measurements differ from the date-based estimate.
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Learn more
How to calculate ovulation and find your fertile window
How to estimate when you ovulate from your cycle, which days are most fertile, and how to confirm it with tests and body signs.
How is a due date calculated? From last period, conception or IVF
A due date feels like a deadline but is really the middle of a window. Here is exactly how it is worked out.