dilutioncalculator.co.uk§ Verified 20 Jun 2026 · Reviewed by A. Hargreaves, MChem (Hons)

Alcohol dilution calculator

Two common cases. Dilute lab IMS (96 %) to 70 % v/v for bench surface disinfection. Blend a cask spirit to bottle strength using Pearson's square.

§ MeasureDesk
Concentrate
76.9 ml
Water
4 923.1 ml
Total at strength
5 000 ml
1.54 % v/v
§ PourScale · true-to-ratio
concentrate 1.54 %water 98.46 %

§ 196 % IMS to 70 %

C₁V₁=C₂V₂ with C₁ = 96, C₂ = 70, V₂ = 1 000 ml: V₁ = (70 × 1 000) ÷ 96 = 729.2 ml of IMS. Top up to 1 000 ml with distilled water. Result: 70 % v/v alcohol disinfectant.

Ethanol and water contract on mixing. The 1 000 ml total is approximate; for a precise 70 % w/w, use HMRC spirit-strength tables.[17]

§ 2Pearson's square · cask 60 % to bottle 46 %

  1. Place high (60) top-left, low (0 for water) bottom-left, target (46) in the middle.
  2. Diagonal subtraction: 60 − 46 = 14 parts water (bottom-right). 46 − 0 = 46 parts cask (top-right).
  3. Ratio 46 cask to 14 water. For 1 000 ml bottle: cask = 1 000 × (46/60) = 766.7 ml; water = 233.3 ml.

§ 3Related