# Gestation Calculator

> Estimate an animal due date or breeding date from a typical gestation period.

Page: https://askcalculators.com/calculator/gestation-calculator/
Definition: https://askcalculators.com/calculator/gestation-calculator/definition.json
JSON Schema: https://askcalculators.com/calculator/gestation-calculator/schema.json
Version: 1.0.0
Maintained by: AskCalculators (software project; not a credentialed reviewer)
Qualified review: pending. Automated checks do not establish professional approval.
Page status: Live
Review status: Pending

## Use
Open the calculator page and enter values. Query-string parameters can restore and bookmark a calculation.
Example: https://askcalculators.com/calculator/gestation-calculator/?animal=cow&mode=due&date=2026-09-01&customDays=150

## Inputs
- animal: Animal; type=select; required; default=cow; values=cow|pig|sheep|goat|horse|chicken|quail|dog|cat|rabbit|guineaPig|hamster|ferret|elephant|custom
- mode: Calculate; type=select; required; default=due; values=due|breeding
- date: Known date; type=date; required; default=2026-09-01
- customDays: Custom gestation period (days); type=number; required; default=150; min=1; max=1000

## Outputs
- resultDate: Estimated date; format=date; primary
- gestationDays: Gestation period; format=integer
- gestationWeeks: Approximate weeks; format=number

## Formula
due date = breeding date + gestation days; breeding date = due date − gestation days

## Rules
- Empty optional inputs are undefined, not zero.
- Hidden conditional inputs are ignored.
- Do not invent missing required inputs.

Notice: This educational estimate does not replace veterinary care. Gestation varies by animal, breed, litter, and health.