A ewe is pregnant for about 147 days, or just under five months. Add 147 days to the mating date to get the lambing due date. Lambs can arrive anywhere from about day 142 to day 152, so use the calculator above to see the date and the full window.

How to use the sheep pregnancy calculator

1. Enter the mating date. This is the day the ram was put with the ewe, or the day you saw her served.
2. Leave the gestation length on “Typical sheep (147 days)”. Pick “Custom value” only if your vet or breed society gives you a different number.
3. Press the calculate button.
4. Read the due date first. Then read the window, which shows the earliest and latest likely days.

If the ewe was with a ram for several days, use the first day for the earliest window and the last day for the latest. Run the calculator twice to see both.

How the calculation works

The tool uses one rule. Lambing date = mating date + 147 days. The 147-day figure is the average gestation for sheep. Published sheep calculators use the same average and a normal range of 142 to 152 days.

The tool counts real calendar days, so it handles month lengths and leap years for you. The window is the mating date plus 142 days at the early end and plus 152 days at the late end.

With a custom value, the tool shows a window of five days either side of your number. That is a simple rule of thumb, not a breed standard.

Worked example

A ewe is mated on 15 September 2025.

• Average due date: 15 September 2025 + 147 days = 9 February 2026.
• Earliest likely date: + 142 days = 4 February 2026.
• Latest likely date: + 152 days = 14 February 2026.

So the flock owner should be ready from the start of February. Most lambs should arrive in the days around 9 February. If the ewe has not lambed by 14 February, it is time to call a vet.

Reference table

Quick guide for ewes mated on the 15th of each month (non-leap year, 147 days).

Mated on	Average due date
15 August	9 January
15 September	9 February
15 October	11 March
15 November	11 April
15 December	11 May

Point	Days after mating
Earliest normal lambing	142
Average (due date)	147
Latest normal lambing	152

Ewes usually have one to three lambs. Some have more. [CHECK: confirm litter size wording against a vet or extension source.]

Tips and common mistakes

• Using the wrong start date. Count from mating, not from the day you suspected pregnancy.
• Treating the due date as exact. Plan for the whole window. Get your lambing area ready before the early date.
• Guessing the mating date. If a ram ran with the flock, you may only know a range. Use the range to build a window.
• Forgetting a record. Write the mating date, due date and window in a flock calendar. Add vet visits and feed changes too.
• Skipping vet advice on feed. Late pregnancy often needs a feed change. Ask your vet or local extension service what suits your breed and pasture.
• Waiting too long. If a ewe passes the late date with no signs of lambing, or struggles in labour, call a vet at once.

Keeping other livestock too? The same method works with different numbers. See the Goat Pregnancy Calculator or the Cow Pregnancy Calculator.

FAQ

How many days are sheep pregnant?

Sheep are pregnant for about 147 days on average. The normal range is roughly 142 to 152 days, so lambs can arrive a few days either side of the due date.

How long is a sheep pregnant in months?

About five months. The 147-day average is just under five calendar months, so the due date usually falls on a similar day number five months after mating.

How many times can a sheep give birth in a year?

Most flocks lamb once a year. Because gestation is about five months, a ewe can in theory lamb more than once a year, but this depends on breed, season and management. [CHECK: confirm typical lambing frequency with an extension service or vet.]

What time of year do sheep give birth?

It follows the breeding date. Many ewes are bred in autumn, so lambs arrive in late winter or spring in the same hemisphere. Some flocks breed in other seasons.

How can I check if my sheep is pregnant?

Ask a vet. Ultrasound scanning and other vet-led tests can confirm pregnancy. A missed return to heat after mating is only a hint, not proof.