Pharmaceutical Calculators
Molarity Calculator
Calculate solution molarity, mass needed, volume, or moles from molecular weight. Supports multiple units and includes a common pharmaceutical chemical MW reference.
Formula
M = n / V n = mass (g) / MW V in Litres
M = Molarity in mol/L n = moles V = volume in Litres MW = molecular weight g/mol
Mass (g) = M × V × MW Volume (L) = mass / (MW × M)
Mass (g) = M × V × MW Volume (L) = mass / (MW × M)
Molarity
—
mol/L
Millimolar
—
mM
Micromolar
—
μM
mg/mL
—
mg/mL
Mass (g)
—
g
Mass (mg)
—
mg
Mass (μg)
—
μg
Volume (L)
—
L
Volume (mL)
—
mL
Volume (μL)
—
μL
Moles
—
mol
Millimoles
—
mmol
Micromoles
—
μmol
Common Pharmaceutical Chemicals — MW Reference
Click any row to auto-populate the molecular weight field in the calculator above.
| Compound | MW (g/mol) | Common Use |
|---|---|---|
| NaCl (Sodium chloride) | 58.44 | IV saline, isotonicity |
| Glucose (anhydrous) | 180.16 | IV dextrose |
| Mannitol | 182.17 | Osmotic agent, lyophilization |
| Sucrose | 342.30 | Lyophilization stabilizer |
| Sodium phosphate (dibasic) | 141.96 | Buffer |
| Potassium phosphate (monobasic) | 136.09 | Buffer |
| Sodium acetate (anhydrous) | 82.03 | Buffer |
| Acetic acid | 60.05 | Buffer (glacial) |
| Tris base | 121.14 | Buffer |
| EDTA (disodium) | 372.24 | Chelating agent |
| Citric acid (anhydrous) | 192.12 | Buffer |
| Sodium citrate | 294.10 | Buffer |
| Polysorbate 80 | ~1310 | Solubilizer/surfactant |
| HCl (hydrochloric acid) | 36.46 | pH adjustment |
| NaOH (sodium hydroxide) | 40.00 | pH adjustment |
How to Use
1
Select what you want to calculate: Molarity, Mass needed, Volume, or Moles.
2
Enter the known values, or click any compound in the reference table to auto-fill the molecular weight field.
3
Click Calculate — results are shown in multiple units for convenience.
Worked Example
Preparing 500 mL of 150 mM NaCl
MW of NaCl = 58.44 g/mol
Mass = M × V × MW = 0.150 mol/L × 0.500 L × 58.44 g/mol = 4.383 g
Dissolve 4.383 g NaCl in water and adjust volume to exactly 500 mL.
Frequently Asked Questions
Molarity (M) is the number of moles of solute per litre of solution. A 1 M solution contains 1 mole of solute dissolved in enough solvent to make exactly 1 litre of solution. It is the most common unit of concentration in pharmaceutical and laboratory chemistry.
Molarity is moles of solute per litre of solution — it changes with temperature because volume expands or contracts. Molality is moles of solute per kilogram of solvent — it is temperature-independent. For most pharmaceutical and lab applications, molarity is used.
Divide mg/mL by molecular weight (g/mol), then multiply by 1000 to get mM. Formula: mM = (mg/mL ÷ MW) × 1000. Example: 10 mg/mL NaCl (MW 58.44 g/mol): (10 / 58.44) × 1000 = 171 mM.
1 mM = 0.001 mol/L = 10−3 M. Millimolar is commonly used in biochemistry and pharmacology because many biologically active concentrations fall in this range. Similarly, 1 μM = 10−6 mol/L and 1 nM = 10−9 mol/L.
Dissolve 58.44 g of NaCl (1 mol × 58.44 g/mol) in approximately 800 mL of water, then adjust to exactly 1 L using a volumetric flask. This gives a 1 mol/L = 1 M solution. Always add solute to solvent — never solvent to a concentrated acid or reactive solid.