Quick answer: Sheep are pregnant for about 147 days, or just under five months. Most ewes lamb between day 144 and day 152 after breeding. Enter the breeding date, or the day the ram went in, into this sheep gestation calculator. It doubles as a lambing calculator for each ewe.
How long are sheep pregnant?
The sheep gestation period averages about 147 days. Most breeds average between 144 and 151 days, and individual ewes can lamb anywhere from about 138 to 159 days. Ewes within the same breed can differ by 3 to 5 days.
Does breed change the lambing date?
Yes, by a few days. Fast-maturing meat breeds and prolific Finn-cross ewes tend to lamb at about 144 to 145 days. Slower-maturing fine-wool breeds such as Rambouillet average 150 to 151 days. Ewes carrying twins or triplets also tend to lamb a little sooner than those with a single lamb.
Sheep gestation and lambing date table
Due dates below use 147 days. Bred ewes in a group will lamb over a spread of days, so plan around the window:
| Bred on | Lambs due | Normal window |
|---|---|---|
| Jan 1 | May 28 | May 25 – Jun 2 |
| Jan 15 | Jun 11 | Jun 8 – Jun 16 |
| Feb 1 | Jun 28 | Jun 25 – Jul 3 |
| Feb 15 | Jul 12 | Jul 9 – Jul 17 |
| Mar 1 | Jul 26 | Jul 23 – Jul 31 |
| Mar 15 | Aug 9 | Aug 6 – Aug 14 |
| Apr 1 | Aug 26 | Aug 23 – Aug 31 |
| Apr 15 | Sep 9 | Sep 6 – Sep 14 |
| May 1 | Sep 25 | Sep 22 – Sep 30 |
| May 15 | Oct 9 | Oct 6 – Oct 14 |
| Jun 1 | Oct 26 | Oct 23 – Oct 31 |
| Jun 15 | Nov 9 | Nov 6 – Nov 14 |
| Jul 1 | Nov 25 | Nov 22 – Nov 30 |
| Jul 15 | Dec 9 | Dec 6 – Dec 14 |
| Aug 1 | Dec 26 | Dec 23 – Dec 31 |
| Aug 15 | Jan 9 | Jan 6 – Jan 14 |
| Sep 1 | Jan 26 | Jan 23 – Jan 31 |
| Sep 15 | Feb 9 | Feb 6 – Feb 14 |
| Oct 1 | Feb 25 | Feb 22 – Mar 1 |
| Oct 15 | Mar 10 | Mar 7 – Mar 15 |
| Nov 1 | Mar 27 | Mar 24 – Apr 1 |
| Nov 15 | Apr 10 | Apr 7 – Apr 15 |
| Dec 1 | Apr 26 | Apr 23 – May 1 |
| Dec 15 | May 10 | May 7 – May 15 |
How to plan breeding and lambing
Ewes come into heat about every 17 days (14 to 19 days) during the breeding season, and each heat lasts about 30 to 35 hours. That is a shorter cycle than a goat in heat, which comes back about every 21 days. Leaving the ram in for 35 days gives each ewe two chances to be bred. A 60-day period gives three.
Sheep breed mainly as the days get shorter. In much of the US, ewes bred in September, October or November tend to be the most fertile and have the most twins.
If you mark rams with a crayon harness and record the date each ewe is marked, you can enter those dates here for each ewe’s own due date.
Signs a ewe is about to lamb
- Her udder fills and the teats become firm in the last days.
- The area around her tail and vulva looks sunken and soft.
- She wanders off on her own, paws the ground or lies down and gets up often.
- She stops eating or looks back at her sides.
Most ewes lamb without help. Call a vet or an experienced shepherd if she strains hard for 30 minutes to an hour with no progress, or if you see a head without front feet, a single leg or a tail first.
Caring for a pregnant ewe
- Feed well in the last six weeks, when most lamb growth happens. Hunger in the final month is a common cause of trouble.
- Shear or crutch before lambing, so lambs find the teats easily.
- Set up clean, dry lambing pens before the first due date.
The figures above come from Montana State University’s sheep reproduction guide. Keeping goats as well? Our goat gestation calculator uses a 150-day average. Running cattle on the same farm? Plan calving with the cattle gestation table, or see every species in our gestation chart.
Frequently asked questions
How many months is a sheep pregnant?
About five months. At 147 days, it is a few days short of five calendar months.
Can a ewe lamb at 140 days?
Yes. Individual ewes can lamb from about 138 days, especially in early-maturing breeds or when carrying several lambs. Lambs born much earlier may be weak.
How can I tell if a ewe is pregnant?
A ewe that does not return to heat about 17 days after breeding may be pregnant. An ultrasound scan by a vet or trained scanner can confirm it and count lambs.
At what age can ewe lambs be bred?
Ewes reach puberty at about 5 to 12 months, depending on breed, nutrition and birth date. Many farms aim for about 65% of mature body weight before breeding.
When is lambing season?
With fall breeding, most flocks lamb in late winter and spring, about five months later.
Why did my ewes lamb over several weeks?
Each ewe is bred on her own heat, which comes about every 17 days. Ewes that missed the first heat are bred on the next one, so lambing spreads out.