Calculator Inputs
Example data table
| Scenario | Inputs | Expected outcome |
|---|---|---|
| NaCl from mass | 5.84 g, 58.44 g/mol, 1.0 L, 100% purity | 0.10 mol/L solution |
| Acid from moles | 0.25 mol in 250 mL | 1.00 mol/L concentration |
| Prepare sodium hydroxide | 0.50 mol/L, 500 mL, 40 g/mol, 99% purity | About 10.10 g weighed solid |
| Dilute stock solution | 2.0 M to 0.25 M, final volume 1000 mL | 125 mL stock plus 875 mL diluent |
Formula used
Molarity expresses moles of solute present in one liter of solution.
M = n / V
When mass is known, first convert mass into moles using molar mass.
n = m / MW
If the reagent is not fully pure, adjust the available mass before dividing by molar mass.
mpure = minput × purity / 100
For preparation planning, calculate the required moles and then convert them into grams.
nrequired = M × V
mrequired = n × MW
Dilution uses the equality of moles before and after dilution.
M1V1 = M2V2
Keep volume units consistent by converting every entered value to liters before calculation.
How to use this calculator
- Select the calculation mode that matches your laboratory task.
- Enter the solute, volume, purity, or stock data requested by that mode.
- Choose the correct mass and volume units for each field.
- Press Calculate to show the result block below the header.
- Review the output table for molarity, moles, grams, or dilution volumes.
- Use the CSV or PDF buttons when you need a saved record.
Frequently asked questions
1. What does molarity measure?
Molarity measures the number of moles of solute dissolved in one liter of final solution. It is written as mol/L or simply M.
2. Why does purity affect molarity?
If a reagent is less than 100 percent pure, part of the weighed mass is inactive material. The calculator corrects this before computing moles and concentration.
3. Should I use solvent volume or final solution volume?
Always use final solution volume for molarity. Solvent volume alone can underestimate concentration because dissolving a solute changes the final total volume.
4. Can I calculate dilution from a stock solution?
Yes. Choose the dilution planner, enter stock molarity, target molarity, and final volume. The calculator returns the stock and diluent volumes needed.
5. Why are liters used internally?
Molarity is defined per liter of solution. The calculator converts mL, cL, and uL entries into liters first, then performs the equations consistently.
6. What if I know moles directly?
Use the moles to molarity mode. Enter moles and solution volume, and the calculator will compute molarity without requiring mass or purity data.
7. Can this help me prepare a new solution?
Yes. The preparation mode estimates required moles and grams for a target molarity and final volume, then adjusts the mass for reagent purity.
8. Is this suitable for engineering laboratory work?
It is useful for routine engineering, chemical, and process laboratory calculations. Critical production or safety work should still be checked against your operating procedures.