Free reef chemistry tool
A solution dilution calculator applies C1V1 = C2V2 to find a stock concentration, stock volume, final concentration, or final volume. Enter any three values to get the fourth plus a practical stock-and-diluent recipe.
C1V1 = C2V2
Compatible groups: % / ppm / ppb, mg/L / g/L, or mol/L / mol/L. Your values stay in this browser and are not uploaded.
Dilution result
Stock volume (V1)
Measure stock solution
0.1 L
Add diluent
0.9 L
Substituted formula
V1 = (1 percent × 1 liters) ÷ 10 percent
C1 is the stock concentration, V1 is the stock volume, C2 is the desired final concentration, and V2 is the total final volume. The amount of solute stays constant while diluent increases the total volume and lowers concentration.
The equation assumes the concentration definitions are compatible and volumes are additive. It does not account for chemical reactions, density changes, dissociation, product purity, or active-ingredient differences.
Percent, ppm, and ppb are dimensionless ratios and can be converted directly. mg/L and g/L are mass-per-volume units. mol/L measures amount of substance and needs molar mass before it can convert to a mass or ratio unit.
For commercial aquarium supplements, confirm whether a label reports elemental concentration, compound concentration, solution percentage, or a product-specific dose before using the result.
Step 1
Select C1, V1, C2, or V2 as the value you want to calculate.
Step 2
Add the known stock and final concentrations and volumes with their units.
Step 3
Keep concentration units in the same family; volume units are converted automatically.
Step 4
Use the stock-plus-diluent recipe, then confirm the finished solution before aquarium use.
The Printable Reef Logbook gives you water testing, dosing, maintenance, and livestock worksheets you can print or save as a PDF.
A solution dilution calculator uses C1V1 = C2V2 to find the stock amount or concentration needed to prepare a weaker final solution. C1 and V1 describe the stock; C2 and V2 describe the finished solution.
Enter any three known values, choose the fourth value to solve, and keep concentration units compatible. The calculator converts volume units, rearranges the equation, and reports both stock and diluent amounts.
Yes. Percent, ppm, and ppb are compatible ratio units: 1% equals 10,000 ppm or 10,000,000 ppb. mg/L and g/L form a separate compatible group, while mol/L requires mol/L unless molar mass is known.
Ordinary dilution adds a solvent or diluent, so it lowers concentration. If the target is stronger than the stock, you need concentration, evaporation, or more solute rather than a dilution calculation.
Use the result only to prepare a solution after confirming the product label, concentration basis, and units. Test the finished solution and follow aquarium-specific dosing limits before adding anything to livestock water.
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