Solution Dilution Calculator for Concentration and Volume

Solution dilution reduces a solute concentration by adding solvent without changing the amount of dissolved solute. The familiar dilution equation states that stock concentration multiplied by stock volume equals final concentration multiplied by final volume. This calculator rearranges that relationship to find any one of the four quantities. It is useful when preparing laboratory standards, buffers, reagents, cleaning solutions, culture media, and other mixtures from a more concentrated stock. Stock concentration is the concentration before dilution, while final concentration describes the completed mixture. Stock solution volume is the measured portion taken from the stock, and final solution volume is the total volume after solvent has been added. Final volume is not normally the amount of solvent alone. For example, if 20 milliliters of stock must be diluted to 100 milliliters, add solvent until the combined solution reaches 100 milliliters rather than adding 100 milliliters of solvent. Concentration units must match on both sides of the equation. You can use molarity, mass per volume, percent concentration, or another proportional concentration scale when both concentration entries share that scale. Likewise, both volume values must use the same unit. The calculator displays milliliters for convenience, but the numerical relationship also works with liters, microliters, or gallons when both volumes use one consistent unit. Convert unlike units before entering values. The equation assumes that solute quantity is conserved, volumes are additive enough for the intended precision, and no reaction, precipitation, evaporation, or decomposition changes the solute. Real laboratory preparation also depends on calibrated glassware, pipette technique, temperature, purity, and complete mixing. Highly concentrated acids or exothermic mixtures require an approved safety procedure; arithmetic alone does not determine safe mixing order. Choose the desired unknown, enter the remaining three measurements, and calculate. A target concentration above the stock concentration describes concentration rather than dilution and may require solvent removal or more concentrated stock. Check that the required stock volume does not exceed the requested final volume for an ordinary dilution. Round the result according to the least precise input and document the chemical identity, units, final volume, and preparation method.