Sheep Birthing Date Calculator: Calculate Expected Lambing Dates

Lambing is one of the most labour-intensive periods in the sheep farming calendar. Knowing when your ewes are due allows you to prepare lambing pens, stock up on colostrum replacer, arrange lambing checks, and plan the labour needed for the few weeks around lambing. The Sheep Birthing Date Calculator gives you the expected lambing date from the date of tupping.

Sheep gestation is 147 days (five months minus five days). The calculator returns the expected lambing date, a countdown from today, and a suggested date to begin close monitoring (day 140, when ewes should be moved to lambing paddocks). It also flags the date to move to a flushing diet if that is part of your management plan.

For flocks with a defined tupping period, a range of expected lambing dates is shown rather than a single date, helping you plan for the spread of lambings.

The 147-day average gestation period is standard across virtually all domestic sheep breeds, with minor variation between individuals (143–150 days). This figure is used by AHDB, DEFRA, and all major UK sheep husbandry references. Prolific breeds may sometimes deliver a day or two early with large litters; this is normal.

Enter the date of tupping (the date the ram was introduced to the ewes, or the date a specific ewe was observed to be served). The calculator returns the expected lambing date and key preparation milestones. For batch lambing, enter the start and end date of the tupping period to see the full expected lambing window.