Sheep Wool Yield Calculator
Estimate the clean (scoured) wool yield from a greasy (raw, shorn) fleece using breed-average yield percentages from USDA Agricultural Research Service data. Enter the total greasy fleece weight, the number of sheep, and select the breed to calculate the expected clean wool weight from your mob. This is an estimate based on breed averages; actual yield should be confirmed by official core testing per ASTM D2525.
Wool yield formula
Total greasy weight (kg) = avg fleece weight x number of sheep
Clean yield (kg) = total greasy weight x (clean yield % / 100)
Clean yield percentages are based on USDA Agricultural Research Service breed characterisation data and the Wool Research Organisation of New Zealand breed averages. Official measurement uses core testing as defined in ASTM D2525 and IWTO-19 (International Wool Textile Organisation).
Breed clean yield reference (USDA ARS)
- Merino: 45-55% clean yield (high lanolin content)
- Rambouillet: 50-60% clean yield
- Corriedale: 55-65% clean yield
- Suffolk: 60-70% clean yield
- Romney: 65-75% clean yield (low lanolin)
- Lincoln: 65-75% clean yield
Sheep wool yield calculator: frequently asked questions
What is the difference between greasy and clean wool yield?
Greasy (raw, shorn) fleece weight includes fibre plus lanolin (wool grease), suint (dried sweat), vegetable matter, and moisture. Clean yield (also called core yield or scoured yield) is the percentage of usable wool fibre remaining after scouring (washing). Clean yield typically ranges from 45% to 75% of greasy weight depending on breed and management.
What are typical clean yield percentages by breed?
According to USDA Agricultural Research Service data: Merino 45-55%, Rambouillet 50-60%, Corriedale 55-65%, Suffolk 60-70%, Romney 65-75%, Lincoln 65-75%. These ranges reflect variation in lanolin content and vegetable matter contamination.
How is clean yield measured officially?
The official method is core sampling, described in ASTM D2525 (Standard Practice for Sampling Wool for Core Testing). A series of wool cores are taken from multiple bales, scoured under controlled conditions, and the clean dry weight is measured and expressed as a percentage of the original sampled weight.
What affects clean yield on my farm?
Key factors include: breed (Merino has highest lanolin), nutrition (well-fed sheep have higher lanolin), vegetable matter contamination (burrs, seeds reduce commercial yield), time since last shearing (longer staple from 12-month growth), and moisture content at time of shearing.
How do I improve clean wool yield?
Use jetting or dipping to reduce wool grease just before shearing (though this can affect some certification programs). Avoid seedy pastures before shearing. Maintain adequate nutrition. Some woolgrowers use sheep covers/coats to exclude vegetable matter. Genetic selection for low-grease breeds also increases clean yield.
Official sources
- USDA Agricultural Research Service: Livestock and Wool Research.
- ASTM International: ASTM D2525 Standard Practice for Sampling Wool for Core Testing.
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology.