Sheep Gestation Calculator
Last updated
A sheep's gestation period is about 147 days, or roughly 4 months and 3 weeks, though it ranges from 144 to 152 days depending on breed and individual animal.
Calculate a lamb due date
Estimated lambing date
Wednesday, 24 March 2027
Earliest
21 Mar 2027
Latest
29 Mar 2027
0 of 147 days elapsed
Milestone timeline
| Day | Milestone | Date |
|---|---|---|
| 17 | Ewe returns to heat if not in lamb — watch the ram's marks | 14 Nov 2026 |
| 45 | Scanning window opens: ultrasound counts lambs from day 45 to 90 | 12 Dec 2026 |
| 100 | Split the flock by lamb count and lift the ration for twins and triplets | 5 Feb 2027 |
| 125 | Clostridial and pasteurella booster so colostrum carries antibodies | 2 Mar 2027 |
| 135 | Crutch or dag the ewes and move them to the lambing paddock or shed | 12 Mar 2027 |
| 147 | Expected lambing | 24 Mar 2027 |
How to use the sheep gestation calculator
- 1. Choose what you know. Enter the breeding date to get a due date, or switch to the target due date mode to work backwards to the breeding date you need.
- 2. Refine the inputs. Pick the breed so the calculator uses the right average gestation length.
- 3. Plan around the range. Use the earliest and latest dates and the milestone timeline to schedule checks, feed changes and preparation of the lambing area.
How long is a sheep's gestation period?
The average is 147 days from breeding to lambing, about 4 months and 3 weeks. Anything between 144 and 152 days is normal, and a typical litter is 1-2 lambs. Treat the calculated date as the middle of that window rather than a fixed appointment.
Sheep gestation table: breeding date to lambing date
Breeding dates one week apart with the matching lambing date at 147 days.
| Breeding date | Expected lambing date |
|---|---|
| 28 Oct 2026 | 24 Mar 2027 |
| 4 Nov 2026 | 31 Mar 2027 |
| 11 Nov 2026 | 7 Apr 2027 |
| 18 Nov 2026 | 14 Apr 2027 |
| 25 Nov 2026 | 21 Apr 2027 |
| 2 Dec 2026 | 28 Apr 2027 |
| 9 Dec 2026 | 5 May 2027 |
| 16 Dec 2026 | 12 May 2027 |
| 23 Dec 2026 | 19 May 2027 |
| 30 Dec 2026 | 26 May 2027 |
| 6 Jan 2027 | 2 Jun 2027 |
| 13 Jan 2027 | 9 Jun 2027 |
How breed changes the lambing date
Selecting a breed swaps the average the calculator uses, which can move the lambing date by more than a week.
| Breed | Average days | Difference |
|---|---|---|
| Average | 147 | — |
| Finnsheep | 143 | -4 days |
| Romanov | 144 | -3 days |
| Dorset | 145 | -2 days |
| Suffolk | 145 | -2 days |
| Texel | 147 | — |
| Merino | 148 | +1 days |
| Rambouillet | 149 | +2 days |
| Border Leicester | 149 | +2 days |
| Karakul | 150 | +3 days |
Working backwards from a target lambing date
If you want lambs on the ground in a particular week, switch the calculator to target date mode and enter the date you are aiming for. It subtracts 147 days to give the breeding date to book, plus the earliest and latest service dates that still land inside your window.