Raw Fleece Scouring Yield Calculator
Enter your fleece weight and breed to find out how much clean wool you will have after washing, how much water and detergent you need, and how many yards of yarn you can expect to spin. Everything runs in your browser - nothing uploaded.
Scouring Results
Full details
Scouring Steps
- 1 Fill a basin or tub with the calculated water volume at 60-65 C (140-150 F). Hot water is essential - it dissolves lanolin. Do not use boiling water as it can felt fine wools.
- 2 Add the detergent and stir gently to dissolve before adding fibre. Power Scour and Unicorn Fibre Wash are both low-suds, fast-rinsing formulas ideal for wool.
- 3 Submerge the fleece and press gently to saturate. Do not agitate or scrub - movement plus heat plus soap causes felting. Leave to soak for 20-30 minutes.
- 4 Lift the fleece out without wringing. Drain the basin, refill with water at the same temperature, and rinse the fleece by soaking again for 10-15 minutes. Repeat once more if the water still looks very dirty.
- 5 Gently squeeze out excess water, roll in a towel, and press to remove moisture. Lay flat or hang in a mesh bag to air dry. The scoured weight shown above is what you should expect once fully dry.
Learn more: raw fleece scouring yield by breed
Clean weight depends on breed
Greasy fleece loses weight in scouring as grease, dirt and vegetable matter wash out. The calculator uses a typical yield for each breed: Merino 60%, Jacob 65%, Corriedale 68%, Shetland 70%, Blue-Faced Leicester 72% and Romney 75%. These are typical figures, so weigh a sample of your own fleece for a better number.
A 1,000 gram greasy Merino fleece comes to 600 grams clean. The same weight of Romney comes to 750 grams, so 150 grams more usable fiber from the same starting weight.
Water and detergent follow the greasy weight
The calculator sizes the bath to the greasy fleece, at 2.5 litres of water per 100 grams. A 1 kg fleece takes 25 litres, and at 3 mL of scouring detergent per litre that is 75 mL, whatever the breed. Follow the dosage on your own detergent's label if it differs.
How the yardage is estimated
Yardage is the scoured weight in ounces times your target WPI (wraps per inch) times 5.7. That constant is fitted to the yarn weight table on Wikipedia, where 100 g of worsted-weight yarn (11 to 15 WPI) runs 200 to 250 meters and 100 g of fine yarn (14 to 24 WPI) runs 350 to 450 meters.
For 100 grams of scoured wool, the calculator gives about 241 yards at 12 WPI, 402 yards at 20 WPI and 643 yards at 32 WPI. A 1 kg greasy Merino fleece scoured to 600 grams and spun at 20 WPI comes to roughly 2,400 yards. Real yardage varies with how you spin and ply.
FAQ
Why does the calculator ask for a target WPI?
Finer yarn has more wraps per inch and goes further per gram. The same 600 grams of clean wool gives very different lengths depending on how fine you spin it, so a yardage figure needs a target thickness.
Is a low-yield breed a worse buy per pound?
Compare the price per clean pound. At $10 per greasy pound, Merino at 60% costs $16.67 per clean pound and Romney at 75% costs $13.33. Yield measures washing loss, not fiber quality, so weigh it against what you want to make.
How accurate is the yardage estimate?
It is a rough guide fitted to a general yarn weight table. Spin tension, singles versus plied yarn and how much twist you add all change the result, so spin and measure a sample before you commit to a project.