Dilution Calculator
Calculate the stock quantity needed for a target concentration and final batch size. Choose a concentration basis and see dilution factors, steps and batch-size comparisons.
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Result
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Calculation steps
Work through one step at a time or reveal the complete calculation. The steps use your current inputs.
How to calculate
Conserve the solute amount using a single concentration basis. For concentrations per volume, C₁V₁ = C₂V₂ and V₁ = C₂V₂/C₁. For mass fractions, replace volumes with masses. The final batch size includes the stock quantity.
required stock quantity = final total quantity × target concentration / stock concentration; dilution factor = stock / target
Worked example
To prepare 500 mL at 2 mol/L from a 10 mol/L stock, use 500 × 2/10 = 100 mL of stock and make the solution up to a final volume of 500 mL. The dilution factor is 5. In a mass/mass example, 500 g at 2% from a 10% stock requires 100 g stock plus 400 g solute-free diluent.
Assumptions and input details
Use the same selected concentration basis for stock and target; never mix mass and volume percentages. Molarity and mass/volume concentrations may exceed 100 numerically; mass/mass and volume/volume percentages are limited to 100. The target must be positive and no stronger than the stock. Volume mixtures may contract or expand, so the nominal volume difference is not an exact solvent dose: make up to the stated final solution volume. Assumes a solute-free diluent, no reaction and no solute loss. This is a quantity calculation, not a chemical handling procedure.
References: OpenStax: molarity and dilution
Unit definitions
Unit selection is independent of language. Each selector contains only units for its physical quantity. Calculations use defined base units internally.
The 19 mass definitions distinguish avoirdupois and troy measures, metric and regional measures. Japanese kin is 600 g; mainland Chinese shijin is 500 g.
The 36 volume definitions distinguish US liquid, US dry and Imperial measures. Cups carry an explicit definition. Japanese shō is 2401/1331 L and a gō is one tenth of it; the explicitly labelled 180 mL rice cup is separate.
Regional measures are not interchangeable merely because their names look similar. This is a documented selection, not a claim to include every historical unit.
NIST measurement tables · UK Imperial definitions · Japanese traditional units · Mainland China and Hong Kong unit distinctions
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
Is my input uploaded?
The calculation runs in your browser. No account, file upload or external AI service is required. Inputs are not saved between page reloads.
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A little space to keep the tools free.