Concentration Calculator

Calculate solution concentrations in multiple units. Enter mass of solute, volume of solution, and molar mass to get molarity, mass/volume %, mass/mass %, ppm, ppb, and more.

Concentration Units: Molarity (M): M = moles / liters moles = mass (g) / molar mass (g/mol) M = (mass / molar mass) / (volume / 1000) Mass/Volume Percent (% w/v): % w/v = (mass of solute in g / volume in mL) × 100 Example: 10 g in 100 mL = 10% w/v Mass/Mass Percent (% w/w): % w/w = (mass solute / mass solution) × 100 mass solution = volume × density Parts Per Million (ppm): ppm = (mass solute / mass solution) × 10⁶ For dilute aqueous: 1 ppm ≈ 1 mg/L Parts Per Billion (ppb): ppb = (mass solute / mass solution) × 10⁹ For dilute aqueous: 1 ppb ≈ 1 μg/L Other Units: g/L = (mass / volume) × 1000 mg/mL = mass / volume Relationships: 1 M = (M × MW) g/L % w/v = (M × MW) / 10 ppm = (M × MW × 1000) for density ≈ 1
Example 1 (NaCl Solution): Mass = 58.44 g NaCl Volume = 1000 mL Molar Mass = 58.44 g/mol (NaCl) Density = 1.0 g/mL Moles = 58.44 / 58.44 = 1.00 mol Molarity = 1.00 / 1.0 = 1.00 M % w/v = (58.44 / 1000) × 100 = 5.84% % w/w = (58.44 / 1000) × 100 = 5.84% g/L = 58.44 g/L ppm = 58,440 ppm Example 2 (Glucose Solution): Mass = 18.0 g C₆H₁₂O₆ Volume = 500 mL Molar Mass = 180.16 g/mol Density = 1.0 g/mL Moles = 18.0 / 180.16 = 0.0999 mol Molarity = 0.0999 / 0.5 = 0.200 M % w/v = (18.0 / 500) × 100 = 3.60% g/L = 36.0 g/L ppm = 36,000 ppm Example 3 (Trace Contaminant): Mass = 0.001 g (1 mg) Volume = 1000 mL Molar Mass = 100 g/mol Density = 1.0 g/mL Molarity = 1×10⁻⁵ M = 10 μM % w/v = 0.0001% ppm = 1 ppm ppb = 1000 ppb Example 4 (Concentrated H₂SO₄): Mass = 98 g Volume = 100 mL Molar Mass = 98.08 g/mol Density = 1.84 g/mL (actual for conc. H₂SO₄) Molarity = 10.0 M % w/v = 98% % w/w = (98 / 184) × 100 = 53.3% This shows importance of density! Example 5 (Saline Solution): Mass = 0.9 g NaCl (physiological saline) Volume = 100 mL Molar Mass = 58.44 g/mol Density = 1.0 g/mL Molarity = 0.154 M % w/v = 0.9% (0.9% saline) ppm = 9,000 ppm

What is molarity (M)?

Molarity is moles of solute per liter of solution: M = mol/L. It's the most common concentration unit in chemistry. For example, 1 M NaCl means 1 mole (58.44 g) of NaCl dissolved in enough water to make 1 liter of solution.

What is mass/volume percent?

Mass/volume percent (% m/v or % w/v) = (mass of solute in g / volume of solution in mL) × 100. For example, 10% w/v means 10 g solute per 100 mL solution. Common in pharmaceutical and medical applications.

What are ppm and ppb?

Parts per million (ppm) = (mass solute / mass solution) × 10⁶. Parts per billion (ppb) = (mass solute / mass solution) × 10⁹. Used for trace concentrations in environmental and analytical chemistry. 1 ppm ≈ 1 mg/L for dilute aqueous solutions.

How do I convert between concentration units?

You need molar mass and density. From molarity to % w/v: multiply M by molar mass to get g/L, then divide by 10 for g/100mL (%). From ppm to molarity: divide ppm by molar mass, then by 1000 for dilute solutions.

What is mass percent?

Mass percent (% m/m or % w/w) = (mass of solute / mass of solution) × 100. Different from volume percent. For example, 5% w/w NaCl in water means 5 g NaCl in 100 g total solution (95 g water + 5 g NaCl).

How do I calculate molarity from mass and volume?

First find moles: moles = mass (g) / molar mass (g/mol). Then molarity = moles / volume (L). For example, 11.7 g NaCl (MW = 58.44) in 200 mL: moles = 11.7/58.44 = 0.200 mol; M = 0.200/0.200 = 1.00 M.

What is the difference between molarity and molality?

Molarity (M) = mol/L of solution. Molality (m) = mol/kg of solvent. Molarity changes with temperature (volume expands), but molality doesn't. Molality is used for colligative properties and precise work.

How do I prepare a solution of known concentration?

Calculate mass needed: mass = molarity × volume (L) × molar mass. Weigh this amount, add to volumetric flask, dissolve, then add solvent to reach the mark. For example, for 500 mL of 0.1 M NaCl: mass = 0.1 × 0.5 × 58.44 = 2.92 g.

What density should I use for dilute aqueous solutions?

For dilute solutions (<5% solute), assume density ≈ 1.00 g/mL (same as water). For concentrated solutions, use actual density values from tables. This affects conversions between mass-based and volume-based units.

Can I use this for gases?

No, this calculator is for liquid solutions. Gas concentrations use different units: mol/L (for ideal gas law), ppm/ppb (volume basis), or g/m³. At STP, 1 mole of ideal gas = 22.4 L, so conversions differ from liquids.

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