Sheep gestation: when is my ewe due?
Type the day the ewe was bred. The sheep gestation calculator gives the estimated lambing date, the normal lambing window, how many days along she is today, and when to watch for heat if she did not settle.
- Estimated lambing date
- December 30, 2026
Your ewe is due to lamb about December 30, 2026, between December 26, 2026 and January 3, 2027.
- Earliest normal lambing date
- December 26, 2026
- Latest normal lambing date
- January 3, 2027
- Days along
- 60
- Days to the estimated lambing date
- 88
- Where she is now
- Day 60 of about 148: 88 days to the estimated lambing date.
- Next heat if she did not settle
- August 21, 2026
Answer for the example date Saturday, October 3, 2026. It changes to today's date when the page loads.
Estimated lambing date: December 30, 2026. Your ewe is due to lamb about December 30, 2026, between December 26, 2026 and January 3, 2027.
How to calculate
Computes a ewe’s lambing date from the breeding date (148 days), the normal lambing window of 144 to 152 days, how many days along she is, and when to watch for heat if she did not settle.
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 ewe is due to lamb about December 30, 2026, between December 26, 2026 and January 3, 2027.
Method: Lambing date = breeding date + 148 days; normal window = breeding date + 144 to 152 days; next heat = breeding date + 17 days.
- The estimate of 148 days is the gestation Alabama Extension plans with; the window of 144 to 152 days is from University of Missouri Extension.
- Days count from the breeding date as day 0. Breed and the number of lambs change the length a little.
- A ewe that did not settle comes back into heat about one estrous cycle after breeding; Merck gives 16 to 17 days, and the date uses 17.
Worked examples
Each example is checked against the calculator on every build.
- Breeding date 2026-04-01, Today’s date 2026-06-01 gives Estimated lambing date 2026-08-27, Earliest normal lambing date 2026-08-23, Latest normal lambing date 2026-08-31, Days along 61, Days to the estimated lambing date 87, Next heat if she did not settle 2026-04-18, Where she is now Day 61 of about 148: 87 days to the estimated lambing date..Source: Alabama Cooperative Extension System, Reproductive Management: Dairy Goats and Sheep (Table 3: numbers based on a 148-day gestation period), https://www.aces.edu/blog/topics/sheep-goats/reproductive-management-dairy-goats-and-sheep/ (retrieved 2026-10-03); University of Missouri Extension, Breeding Season Considerations for Sheep and Goats, G2611 (the gestation period ranges between 144 and 152 days), https://extension.missouri.edu/publications/g2611 (retrieved 2026-10-03); Merck Veterinary Manual, Reproductive Physiology of Sheep (in ewes, estrous cycles average 16 to 17 days), https://www.merckvetmanual.com/management-and-nutrition/management-of-reproduction-sheep/reproductive-physiology-of-sheep (retrieved 2026-10-03); 1 April 2026 + 144, 148 and 152 days
- Breeding date 2027-11-01, Today’s date 2028-03-30 gives Estimated lambing date 2028-03-28, Earliest normal lambing date 2028-03-24, Latest normal lambing date 2028-04-01, Days along 150, Days to the estimated lambing date -2.Source: Alabama Cooperative Extension System, Reproductive Management: Dairy Goats and Sheep (Table 3: numbers based on a 148-day gestation period), https://www.aces.edu/blog/topics/sheep-goats/reproductive-management-dairy-goats-and-sheep/ (retrieved 2026-10-03); University of Missouri Extension, Breeding Season Considerations for Sheep and Goats, G2611 (the gestation period ranges between 144 and 152 days), https://extension.missouri.edu/publications/g2611 (retrieved 2026-10-03)
How it works
The calculator adds whole days to the breeding date:
| Output | Days after breeding | Source |
|---|---|---|
| Estimated lambing date | 148 | Alabama Extension’s planning gestation |
| Earliest normal lambing date | 144 | University of Missouri Extension |
| Latest normal lambing date | 152 | University of Missouri Extension |
| Next heat if she did not settle | 17 | Merck Veterinary Manual: estrous cycle of 16 to 17 days (the later day) |
- Days along = whole days from the breeding date to today’s date. The breeding date is day 0.
- Days to the estimated lambing date = 148 − days along. It is negative once the date has passed.
- Where she is now, by days along (d): past the latest normal date when d is more than 152 (“Day d: past the latest normal lambing date (day 152). Call your vet.”); in the lambing window when d is from 144 to 152 (“Day d: in the lambing window (days 144 to 152).”); otherwise “Day d of about 148: (148 − d) days to the estimated lambing date.”
Rules. Today’s date may not be before the breeding date: then there is no answer and the page says so. Both dates are from 1 January 1900 to 31 December 2200. Calendar days count leap days (2028 has 29 February).
Output format. Dates show as month, day and year. Days along and days to the lambing date are whole numbers.
Worked examples by hand
Bred on 1 April 2026, counted on 1 June 2026. + 144, 148 and 152 days = 23, 27 and 31 August 2026. Next heat: + 17 days = 18 April 2026. From 1 April to 1 June is 30 + 31 = 61 days, so 148 − 61 = 87 days to go.
Bred on 1 November 2027, counted on 30 March 2028. 2028 is a leap year. + 144, 148 and 152 days = 24 March, 28 March and 1 April 2028. From 1 November to 30 March is 30 + 31 + 31 + 29 + 29 = 150 days, so 148 − 150 = −2 days: the estimate passed 2 days ago, and she is in the lambing window.
Other questions people ask
How long is a sheep pregnant?
About 148 days, or 5 months. University of Missouri Extension gives a range of 144 to 152 days, and Alabama Extension plans lambing on a 148-day gestation.
How is the lambing date worked out?
The calculator adds 148 days to the breeding date. The earliest and latest normal dates add 144 and 152 days. A ewe bred on 1 April 2026 is due about 27 August 2026.
What if the ram was with the flock for weeks?
Type the day the ram went in for the first possible lambing date, then the day he came out for the last. Marking harnesses or crayons on the ram show which ewes were bred and when.
When will she come back into heat if she is not pregnant?
Merck gives an estrous cycle of 16 to 17 days for ewes. The calculator shows the date 17 days after breeding; watch from a day before. No heat then is a first sign that she settled.
What if my ewe goes past the latest date?
Call your vet. A ewe past day 152, or one that strains for a long time without a lamb, needs a check.
Do breed and the number of lambs change the date?
A little. Ewes carrying twins or triplets often lamb a few days earlier than ewes with a single lamb, and breeds differ by a few days.