Molarity Calculator
Choose what you need to calculate: molarity from solute mass and final solution volume, solute mass for a target concentration, or a single dilution step. Supply the required quantities and units below. A chemical formula can fill molar mass; molar mass by itself does not determine concentration.
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Molarity calculator
Check the mode before entering values. Volume means the final solution volume. Use a positive molar mass and a nonzero volume for molarity; enter non-negative physical quantities. This form is a calculation aid and does not validate every chemical formula or missing quantity.
| Mode | Required inputs | Outputs |
|---|---|---|
| Mass needed | Molar mass (g/mol), target concentration (M, mM or µM), final volume (L, mL or µL) | Moles and solute mass; mass = concentration × litres × molar mass |
| Molarity | Molar mass (g/mol), solute mass (g, mg or kg), final solution volume (L, mL or µL) | Moles, molarity (M, mM or µM) and mass concentration (g/L) |
| Single dilution | Stock C1 (M), target C2 (M), final V2 (mL) | Stock volume V1 (mL) and dilution factor; V1 = C2 × V2 ÷ C1 |
Solution Prep Lab Pack
Printable lab aids: solution preparation worksheet, a common reagents molar mass table, dilution series planner (Excel), molarity practice problems with answers and a reagent label sheet.
- Prep worksheet (PDF/DOCX)
- Molar masses (PDF/XLSX)
- Dilution planner (XLSX)
- Practice problems (PDF, DOCX)
- Reagent labels (PDF)
Formats: PDF, DOCX, XLSX. Instant download after payment (link valid 72 hours, up to 5 downloads). AI-assisted: the templates were drafted with AI help and reviewed and laid out before publishing.
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Free sample: Common Reagent Molar Masses (PDF, 49 KB)
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License: personal and classroom use. Teachers may print and photocopy these files for the students in their own classes, and share them in a password-protected class space (e.g. Google Classroom). Please do not resell, redistribute, or post the files on public websites. One purchase covers one teacher.
Free printables
Single sheets you can print right now, no sign-up. The full pack adds every sheet in one download plus the editable files.
Printable Molarity Practice Problems
Printable Reagent Labels PDFWhat molarity means
Molarity (M) is the number of moles of a solute dissolved in one litre of solution: M = moles ÷ litres. A 1 M sodium chloride solution contains one mole of NaCl — 58.44 g — in every litre of solution. Note that the volume is of the final solution, not the solvent added, so you dissolve the solute in less solvent and then make it up to the final volume in a volumetric flask.
Key formulas
| To find | Formula |
|---|---|
| Moles | n = mass ÷ molar mass |
| Molarity | M = n ÷ V (litres) |
| Mass needed | mass = M × V × molar mass |
| Dilution | C1 × V1 = C2 × V2 |
| Mass concentration | g/L = M × molar mass |
| Millimolar | 1 mM = 0.001 M |
Check the quantities before calculating
- Choose Mass needed, Molarity, or the single dilution mode.
- For the first two modes, enter a formula or supply a known molar mass in g/mol. Changing the formula overwrites the molar-mass field.
- Select the units for mass, concentration and final solution volume explicitly.
- Read the result and verify that the inputs match the quantities in your problem.
Worked examples
| Mode | Given quantities | Calculation | Result |
|---|---|---|---|
| Mass needed | NaCl: 58.440 g/mol; 0.5 M; 250 mL | 0.5 × (250 ÷ 1000) × 58.440 | 7.305 g |
| Molarity | NaCl: 58.440 g/mol; 7.305 g; 250 mL | (7.305 ÷ 58.440) ÷ (250 ÷ 1000) | 0.5 M |
| Single dilution | C1 = 2 M; C2 = 0.1 M; V2 = 500 mL | 0.1 × 500 ÷ 2 | 25 mL stock; 20× dilution |
The table retains the unrounded mass calculation. The tool formats mass and concentration to four significant figures and may switch to mg, µg, mM or µM.
Entering formulas
| Input | Reads as |
|---|---|
| NaCl | sodium chloride |
| Ca(OH)2 | calcium hydroxide — brackets multiply |
| CuSO4·5H2O or CuSO4.5H2O | hydrate: adds 5 water molecules |
| C6H12O6 | glucose |
| K4[Fe(CN)6] | square brackets work too |
| (NH4)2SO4 | ammonium sulfate |
Element symbols are case-sensitive: Co is cobalt, CO is carbon monoxide. Atomic masses are standard atomic weights; for isotopically labelled compounds, enter the molar mass directly.
Molarity, molality and percent
Molarity uses litres of solution and changes slightly with temperature because liquids expand. Molality (mol per kg of solvent) doesn’t, which is why it is used in physical chemistry for freezing-point and boiling-point calculations. Percent concentrations are also common: % w/v is grams per 100 mL, so a 0.9% saline is 9 g/L — about 0.154 M NaCl.
One dilution step, not a serial dilution tool
This mode solves one C1V1 = C2V2 step with concentrations in M and final volume in mL. It has no list of serial steps and no direct ratio or dilution-factor input. A target stronger than the stock is rejected. The calculated solvent difference is approximate; the final volume is the quantity supplied to the equation.
Accuracy tips in the lab
- Use a volumetric flask, not a beaker, to make up the final volume.
- Weigh by difference for hygroscopic solids, and work quickly.
- Check whether your reagent is anhydrous or a hydrate — the label formula matters.
- Allow solutions that warm up on dissolving to cool before making up to the mark.
- For very small masses, make a more concentrated stock and dilute it rather than weighing tiny amounts.
- Record lot numbers and calculations on the preparation sheet.
Converting between units
| From | To | How |
|---|---|---|
| M | mM | × 1,000 |
| mM | µM | × 1,000 |
| M | g/L | × molar mass |
| g/L | mg/mL | same number |
| % w/v | g/L | × 10 |
| ppm (dilute aqueous) | mg/L | approximately the same |
Worked example with a hydrate
To make 100 mL of 0.1 M copper(II) sulfate from the blue pentahydrate crystals, type CuSO4·5H2O: the molar mass is about 249.68 g/mol. Moles needed = 0.1 mol/L × 0.100 L = 0.010 mol, so weigh out 2.497 g of crystals. Using the anhydrous molar mass (159.60 g/mol) by mistake would give 1.596 g — a solution about 36% too weak. Dissolve the crystals, make up to 100 mL in a volumetric flask and mix well.
Safety
Always add concentrated acid to water, never water to acid, and wear eye protection when handling chemicals. Check safety data sheets for the substances you use. Dilution calculations assume volumes add ideally; for concentrated solutions, make up to the final volume rather than adding a calculated amount of solvent.
Privacy
The calculator runs in your browser; nothing is uploaded.
Frequently asked questions
How do I calculate molarity?
Divide moles of solute by litres of solution.
How many grams of NaCl for 1 L of 1 M solution?
58.44 g.
What is C1V1 = C2V2?
The dilution equation: stock concentration × stock volume = final concentration × final volume.
What is the difference between M and mM?
1 M = 1,000 mM.
Can it handle hydrates?
Yes, enter them like CuSO4·5H2O or CuSO4.5H2O.
Is molarity the same as molality?
No, molality uses kilograms of solvent instead of litres of solution.
Why do hydrates have a larger molar mass?
Because the water molecules in the crystal add to the mass you weigh.
What does 1 N (normality) mean?
Equivalents per litre; for an acid like H2SO4 with two acidic protons, 1 M = 2 N.
Is anything uploaded?
No, everything runs locally.
May I print and share these worksheets with my class?
License: personal and classroom use. Teachers may print and photocopy these files for the students in their own classes, and share them in a password-protected class space (e.g. Google Classroom). Please do not resell, redistribute, or post the files on public websites. One purchase covers one teacher.
Does NaCl or HCl have one fixed molarity?
No. Molarity describes a particular solution. You need the solute amount and final solution volume. The same compound can be present at many concentrations.
Can molar mass alone give molarity?
No. For this form’s mass-to-molarity mode, you also need solute mass and final solution volume: molarity = (mass ÷ molar mass) ÷ litres.
Can I enter moles directly?
There is no moles-input box. This form derives moles from mass and molar mass, or from target concentration and volume.
Are malformed formulas always rejected?
No. Use a verified formula with correctly matched brackets and positive atom counts. The formula reader supports common bracketed formulas and hydrates, but it is not a complete chemistry validator.