How much dye for fabric: the dye calculator formula
Depth of shade is the weight of dye as a percentage of the dry fabric weight. Dye needed (g) = dry fabric weight (g) x depth of shade (%) ÷ 100. On the default, 500 g x 2% = 10 g of dye powder. Slide to the pastel end, 0.5%, and the same fabric needs 2.5 g; at the deep end of the slider, 5%, it needs 25 g. Per kilogram of fabric that is 5 g, 20 g and 50 g. Weigh the fabric dry, before wetting it, because the percentage is of dry weight. Your dye maker’s instructions may give a different depth for the colour you want; use theirs and the calculator does the grams.
Dyeing cost per kg and fabric dyeing cost per meter
Dyeing cost per kg of fabric = (dye + salt, soda or other auxiliaries + water and fuel + labour) ÷ kg of fabric. The calculator gives the grams of dye; multiply by the price per gram on your dye invoice. For example, at an illustrative ₹400 a kilogram of dye, the default 10 g costs ₹4. For a cost per metre, first find what a metre weighs: GSM x width in metres. A 150 GSM fabric 44 in (1.12 m) wide weighs about 168 g a metre, so 3 m is about 503 g, close to the calculator’s 500 g default. Divide your batch cost by the metres in the batch.
Liquor ratio: how much water for the dye bath
The liquor ratio is litres of water per kilogram of dry fabric. The calculator uses 1:20, 20 litres per kilogram, so the default 500 g needs 10 litres. If your dye’s instructions give a different ratio, multiply the fabric weight in kilograms by that number instead: 500 g at 1:30 is 15 litres. Keep the ratio the same from batch to batch when you are matching a shade, because a different amount of water changes how the dye takes.
Fabric dye calculator: getting an even shade
Weigh the fabric dry and the dye on a scale that reads to the gram, since small batches need only a few grams. Dissolve the dye fully before it goes into the bath, wet the fabric first, and keep it moving. Test a swatch from the same roll before the whole batch, and note the weight, depth and ratio you used so the next batch matches. Follow the dye maker’s instructions for salt, soda, temperature and time: they differ by dye type and fibre.