How to Calculate Gestation
What is Gestation?
A gestation calculator estimates the due date or gestational age for humans and animals based on the breeding date or last menstrual period. Gestation length varies significantly by species — from 16 days (hamsters) to 660 days (elephants).
Step-by-Step Guide
- 1Human: 280 days from LMP (40 weeks), or 266 days from conception
- 2Add gestation length to breeding/conception date to find due date
- 3Gestational age = days elapsed since LMP or conception
- 4First trimester: 0–13 weeks; Second: 14–26; Third: 27–40
Worked Examples
Input
Breeding date: 1 March (dog)
Result
Expected whelp date: ≈ 1 June (63-day gestation)
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