Sheep Gestation Calculator

Enter the date the ram went in (and came out) to get the lambing date, the full lambing window and a pre-lambing checklist.

The day the ewe was bred or inseminated, or the day the ram went in.
For pasture breeding. Widens the window.

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Sheep Gestation Calculator · HerdMath

How it works

Sheep carry lambs for about 147 days, just under 5 months, with most ewes lambing between day 142 and day 152. Ewes cycle every 17 days or so during the breeding season. That's why flocks often plan a 34-day (two-cycle) joining period.

How to use it

Enter the ram-in date. If the ram stayed with the flock, add the ram-out date so the window covers the whole lambing period. Pick a breed if it applies.

Reference chart

BreedTypical gestation
Average (most breeds)147 days
Katahdin147 days
Dorper147 days
Suffolk145 days
Hampshire145 days
Dorset145 days
Babydoll Southdown145 days
Merino150 days

Frequently asked questions

How long is a sheep pregnant?

About 147 days, just under 5 months. Most ewes lamb between day 142 and day 152.

How long should the ram stay with the ewes?

Sheep cycle about every 17 days, so two cycles (about 34 days) gives every ewe two chances to be bred. That keeps the lambing period to roughly 5 weeks.

When can you scan ewes for pregnancy?

Ultrasound scanning works best from about 45 to 90 days after the ram goes in. Scanning also shows singles, twins and triplets so you can feed each group correctly.

Can a ewe lamb early?

Yes, a few days early is normal. Lambs born more than a week early are often weak and need extra care.

Figures are typical values from university extension and breed-association guidance. Estimates only. Individual animals vary — confirm pregnancy and health questions with your veterinarian. Last reviewed 2026-09-18.