Kubelka–Munk Calculator

Kubelka–Munk Formula

Worked Example

A dyed fabric with 20 % reflectance at λmax:

1. K/S = (1 − R)² ÷ 2R, R as a fraction
2. = (1 − 0.2)² ÷ (2 × 0.2) = 1.6

Using K/S in colour measurement

K/S is calculated from the reflectance at the wavelength of minimum reflectance (maximum absorption) for the dye. It is approximately proportional to the dye concentration on the fibre, which makes it the basis for colour strength comparisons and computer recipe prediction. The relation becomes less linear at deep shades and on dark or fluorescent substrates, so measure samples opaque (folded several times) and under the same illuminant and geometry.

More Chemical Processing Calculators

• Beer–Lambert Calculator

  A = ε l c = −log₁₀ T

  ε absorptivity, l path length (cm), c concentration, T transmittance

  Example: A dye solution with absorbance 0.6 in a 1 cm cell, ε = 12 000 L/(mol·cm): Concentration c = 80.3859 µmol/L.

  Open the beer–lambert calculator →

• Dyeing Recipe Calculator

  Dye (g) = weight (g) × shade %

  bath (L) = weight (kg) × liquor ratio; chemical = g/L × bath

  Example: 10 kg of cotton dyed at 2 % shade, 1:10 liquor, 60 g/L salt and 20 g/L soda ash: Dye required = 200 g.

  Open the dyeing recipe calculator →

Frequently asked questions

Sources

Last reviewed: 2026-10-15. Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.