🧪 Concentration Mixing Calculator
Calculate the final concentration when mixing solutions of different concentrations.
Solution A
Solution B
Concentration Mixing Formula
Calculation Method
Salt of A = Amount of A × Concentration of A / 100
Salt of B = Amount of B × Concentration of B / 100
Mixed Concentration = (Salt A + Salt B) / (Solution A + Solution B) × 100
Worked examples
Mixing 200 g of a 10% solution with 300 g of a 20% solution gives (20 + 60) ÷ 500 = 16%.
Mixing 100 g of 5% with 100 g of 25% gives an even 15%, because equal masses simply average the percentages.
What the calculation assumes
The percentages are mass fractions, grams of solute per 100 g of solution, so the amounts must be masses. If your source gives % w/v, convert with the density first. The model assumes nothing reacts and that no material is lost while mixing, and it treats the two solutions as perfectly homogeneous before they are combined.
Frequently asked questions
- Why is 16% not the 15% average of 10 and 20?
- Because the amounts differ. With equal masses the arithmetic mean is exact, but here the heavier 20% solution weighs more and pulls the result up to 16%.
- How do I hit a target concentration?
- Use the mixing rule: parts of the stronger solution to parts of the weaker equal (target − weak) : (strong − target). For 16% from 20% and 10% that is 6 : 4.
- Does the total mass stay the same?
- In this model yes, because solute and water masses simply add. Real mixing can contract slightly, which matters for volume percentages but not for mass percentages.