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Mass percent solution dilution calculator

Household and industrial chemicals are usually sold by mass percentage. Diluting one is the same conservation argument as C1V1 = C2V2, but on mass.

% w/w
% w/w
Concentrate to take
42.8571g
= Exact Mass percent dilution
Diluent to add
457.143
Dilution factor
11.6667
Show the working
  1. Starting strength = 35
  2. Target strength = 3
  3. Final mass wanted = 500
  4. Concentrate to take = 3 * 500 / 35 = 42.8571
  5. Diluent to add = 500 - 42.8571 = 457.143
  6. Dilution factor = 35 / 3 = 11.6667

Values are shown to six significant figures here; the arithmetic itself runs on exact fractions and is only rounded where a number is printed.

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    The formula

    • mass of concentrate = target % x final mass / starting %

    Mass percentages combine cleanly; volume percentages do not, because mixing liquids can change the total volume.

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