Chemistry Calculators

The chemistry tools on this page handle the calculations that come up in general chemistry courses, teaching labs and routine analytical work. Each calculator shows the equation it uses and reports units next to the result, so you can check the steps rather than trust a black box. The tools group naturally into five areas.

Amount of substance and concentration

The moles calculator converts mass or particle count into moles, and the molar mass calculator gives you the gram-per-mole value you need for that conversion. From moles, the molarity calculator returns concentration in mol/L, while the mass percent calculator expresses composition by weight. The dilution factor calculator and alcohol dilution calculator apply C₁V₁ = C₂V₂ to stock solutions and spirits.

Acids, bases and buffers

The pKa to Ka calculator switches between the logarithmic and linear forms of the acid dissociation constant. The Henderson-Hasselbalch calculator predicts the pH of a buffer from pKa and the acid-to-base ratio, and the buffer capacity calculator tells you how much strong acid or base a buffer can absorb before its pH moves by one unit.

Reactions and yield

The theoretical yield calculator uses the limiting reagent and stoichiometric ratio to find the maximum product mass. Enter the mass you actually isolated into the percent yield calculator to grade the reaction.

Colligative properties and gases

The freezing point depression and boiling point elevation calculators apply ΔT = i·K·m to solutions of salts, sugars and antifreeze. The gas density calculator uses the ideal gas law to find density from pressure, temperature and molar mass.

Spectroscopy and clinical chemistry

The Beer-Lambert law calculator relates absorbance, path length and concentration for UV-Vis measurements. The serum osmolality and anion gap calculators cover two common blood chemistry formulas used in medicine and biochemistry.

Tips for accurate answers

Use the right molar mass. Water is 18.015 g/mol, but hydrated salts such as CuSO₄·5H₂O include the water of crystallisation (249.69 g/mol, not 159.61).
Keep volumes in litres for molarity. 250 mL is 0.250 L. A missed conversion produces a concentration a thousand times too high.
Watch significant figures. A balance reading of 2.50 g does not justify a result quoted to six decimal places.
Temperature matters for gases and pH. Ideal gas results need kelvin, and pKa values shift with temperature; the defaults assume 25 °C.

Example: preparing a 0.100 M NaCl solution

You need 500 mL of 0.100 M sodium chloride. The molarity calculator tells you that 0.500 L × 0.100 mol/L = 0.0500 mol. The molar mass calculator gives 58.44 g/mol for NaCl, so the moles calculator in reverse yields 0.0500 × 58.44 = 2.92 g. Weigh 2.92 g, dissolve in water and make up to the 500 mL mark. If you later need 0.010 M, the dilution factor calculator shows a 1:10 dilution, for example 50 mL of stock brought to 500 mL.

These calculators support learning and routine lab preparation. Results used for regulated analysis, pharmaceutical preparation or patient care must be verified by a qualified professional.

Table of Contents

Chemistry calculators