A ewe carries her lambs for about five months. Knowing the date helps with feeding, shearing and getting the lambing shed ready.
Enter the date the ram went in, or the date she was bred, to see when lambing should start.
How to use the Sheep Gestation Calculator#
- Enter the breeding date. Use the date of mating, or of insemination.
- Check the length. Leave the average, or enter your vet’s figure for the breed.
- Read your dates. You get the expected date, the likely window and your sheep’s progress.
How long is a sheep pregnant?#
Gestation is about 147 days, with a typical range of 142 to 152. Meat breeds may run a little different from wool breeds, and ewes with twins or triplets may lamb slightly earlier.
| Days | |
|---|---|
| Average | 147 |
| Usual range | 142 to 152 |
Getting ready for the lambs#
Ewes need more feed in the last six weeks, when most of the lamb’s growth takes place. Shearing or crutching before lambing makes it easier to see what’s happening, and a clean, dry, draught-free pen helps. Many flocks scan ewes in mid-pregnancy to count lambs, so they can feed each group correctly.
Lambing can usually be left to the ewe, but call your vet if she strains for a long time without progress or if a lamb is presented wrongly.
Why the date is a window#
Most ewes lamb between day 142 and 152, around an average of 147. Ewes with twins or triplets may lamb slightly earlier, and breed makes a small difference, so treat the due date as the middle of a ten-day window and have the lambing pen ready before it starts. This calculator is a planning tool and doesn’t replace veterinary advice.
A worked example#
A ram is turned in with the ewes on Mon 18 October 2027. A ewe served that day is due on Mon 13 March 2028 at 147 days, with a window from Wed 8 March 2028 to Sat 18 March 2028. The halfway point is Fri 31 December 2027 and the final stretch starts on Sun 20 February 2028, which is day 125.
| Milestone | Day | Date |
|---|---|---|
| Halfway | 74 | Fri 31 December 2027 |
| Final stretch begins | 125 | Sun 20 February 2028 |
| Earliest likely lambing | 142 | Wed 8 March 2028 |
| Expected due date | 147 | Mon 13 March 2028 |
| Latest likely lambing | 152 | Sat 18 March 2028 |
Tracing a flock with marker crayons#
For a whole flock the individual date matters less than the pattern, and the usual tool is a crayon on the ram’s chest. Each ewe he serves is marked on her rump. A ewe’s cycle is about 17 days, so the crayon colour is changed every 16 or 17 days. A ewe that carries the first colour will lamb first, one with the second colour lambs about two weeks later, and any ewe marked twice has returned to the ram and needs to be tracked separately.
If the first colour was applied on Mon 18 October 2027, the second change falls on Thu 4 November 2027, and the third on Sun 21 November 2027. That gives you three lambing blocks to plan around, and a clear idea of which ewes to bring in first.
The last six weeks decide the lambs#
Most of the lamb’s growth happens in the last six weeks, from about Mon 31 January 2028 here. Energy demand climbs, while the ewe’s rumen has less room, so a ewe carrying twins or triplets needs concentrate feed in small portions. Scanning at around 70 to 90 days tells you who is carrying how many, so feed can be tailored. Thin ewes with multiple lambs are at risk of pregnancy toxaemia, which is why scanning is worth the cost.
Shearing four to six weeks before lambing makes ewes seek shelter and gives lambs easier access to the udder. Clostridial boosters usually go in about four weeks ahead, which is Mon 14 February 2028 in this example.
Newborn lambs need colostrum quickly. A common guide is about 50 millilitres per kilogram of body weight in the first six hours, and around 200 millilitres per kilogram across the first day.
Keeping records that save work#
Write the crayon colour or raddle date for each ewe in the lambing book, and note the lambing date and the number of lambs. Ewes that regularly lamb late or have problems each year are worth flagging for culling decisions. A few seasons of notes also let you replace the 147-day average with your own flock’s figure.
Frequently asked questions#
About 147 days, or around five months.
Work backwards from the lambing date you want, using 147 days.
Yes, especially in the final weeks.
If labour is long with no progress, or the lamb’s position is wrong.
Slightly. Ewes carrying twins or triplets tend to lamb a day or two earlier than those with singles, while single lambs are often carried to the later end of the window. Use the flock’s own records to refine the figure, and move ewes to the lambing area at the early end of the range.