# Goat gestation: when is my doe due?

Computes a doe’s kidding date from the breeding date (150 days), the normal kidding window of 147 to 155 days, how many days along she is, and when to watch for heat if she did not settle.

- Page: https://www.acalculator.org/biology/goat-gestation-calculator
- JSON spec: https://www.acalculator.org/biology/goat-gestation-calculator.json
- Version: 44321f25f3f3

## Default answer

Example with the default inputs (Breeding date August 4, 2026, Today’s date October 3, 2026) on the example date Saturday, October 3, 2026: Your doe is due to kid about January 1, 2027, between December 29, 2026 and January 6, 2027.

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| d | Breeding date | The day the doe was bred (mated or inseminated). |
| on | Today’s date | The day to count from, to show how far along the doe is. |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| due | Estimated kidding date | The breeding date + 150 days. |
| earliest | Earliest normal kidding date | The breeding date + 147 days. |
| latest | Latest normal kidding date | The breeding date + 155 days. |
| days | Days along | Whole days from the breeding date to today’s date. |
| left | Days to the estimated kidding date | Whole days from today’s date to the estimated kidding date; negative once it has passed. |
| stage | Where she is now | The stage on today’s date, in one line. |
| heat | Next heat if she did not settle | The breeding date + 21 days, one estrous cycle later. |

## Method

Kidding date = breeding date + 150 days; normal window = breeding date + 147 to 155 days; next heat = breeding date + 21 days.

## Assumptions

- The estimate is the Merck Veterinary Manual’s average gestation of 150 days; the window of 147 to 155 days is from Alabama Extension.
- Days count from the breeding date as day 0. Breed, the number of kids and the doe’s age change the length a little.
- A doe that did not settle comes back into heat about one estrous cycle (21 days) after breeding.

## Worked examples

1. d = 2026-10-01, on = 2026-12-01 gives due = 2027-02-28, earliest = 2027-02-25, latest = 2027-03-05, days = 61, left = 89, heat = 2026-10-22, stage = Day 61 of about 150: 89 days to the estimated kidding date.. Source: Merck Veterinary Manual, Breeding and Parturition of Goats (gestation in goats lasts an average of 150 days; the estrous cycle averages 21 days), https://www.merckvetmanual.com/management-and-nutrition/preventative-health-care-and-husbandry-of-goats/breeding-and-parturition-of-goats (retrieved 2026-10-03); Alabama Cooperative Extension System, Reproductive Management: Dairy Goats and Sheep (lambing and kidding generally occur 147 to 155 days after conception), https://www.aces.edu/blog/topics/sheep-goats/reproductive-management-dairy-goats-and-sheep/ (retrieved 2026-10-03); 1 October 2026 + 147, 150 and 155 days.
2. d = 2027-10-15, on = 2028-03-16 gives due = 2028-03-13, earliest = 2028-03-10, latest = 2028-03-18, days = 153, left = -3. Source: Merck Veterinary Manual, Breeding and Parturition of Goats (gestation in goats lasts an average of 150 days; the estrous cycle averages 21 days), https://www.merckvetmanual.com/management-and-nutrition/preventative-health-care-and-husbandry-of-goats/breeding-and-parturition-of-goats (retrieved 2026-10-03); Alabama Cooperative Extension System, Reproductive Management: Dairy Goats and Sheep (lambing and kidding generally occur 147 to 155 days after conception), https://www.aces.edu/blog/topics/sheep-goats/reproductive-management-dairy-goats-and-sheep/ (retrieved 2026-10-03).

## FAQ

### How long is a goat pregnant?

About 150 days, or 5 months. The Merck Veterinary Manual gives an average of 150 days. Alabama Extension says kidding generally comes 147 to 155 days after conception.

### How is the kidding date worked out?

The calculator adds 150 days to the breeding date. The earliest and latest normal dates add 147 and 155 days. A doe bred on 1 October 2026 is due about 28 February 2027.

### What if I do not know the exact breeding date?

Use the first day the buck was with the doe for the earliest date, and the last day for the latest. The doe is most likely bred during a heat, which lasts about 36 hours.

### When will she come back into heat if she is not pregnant?

The goat estrous cycle averages 21 days, so watch for heat about 21 days after breeding. The calculator shows that date. No heat then is a first sign that she settled.

### What if my doe goes past the latest date?

Call your vet. A doe past day 155, or one that strains for a long time without a kid, needs a check.

### Do breed and litter size change the date?

A little. Small breeds and does with several kids tend to kid a few days earlier. Merck notes that kids born before day 144 may not survive.

## Sources

- Merck Veterinary Manual, Breeding and Parturition of Goats (gestation in goats lasts an average of 150 days; the estrous cycle averages 21 days, with estrus lasting about 36 hours; full review October 2022). https://www.merckvetmanual.com/management-and-nutrition/preventative-health-care-and-husbandry-of-goats/breeding-and-parturition-of-goats (retrieved 2026-10-03)
- Alabama Cooperative Extension System, Reproductive Management: Dairy Goats and Sheep (lambing and kidding generally occur between 147 and 155 days post-conception; August 2019). https://www.aces.edu/blog/topics/sheep-goats/reproductive-management-dairy-goats-and-sheep/ (retrieved 2026-10-03)
- Merck Veterinary Manual, Parturition in Goats (viability can be compromised when kids are delivered before day 144). https://www.merckvetmanual.com/management-and-nutrition/management-of-reproduction-goats/parturition-in-goats (retrieved 2026-10-03)