Equilibrium Constant Calculator

This calculator works out the equilibrium constant Kc of a reversible reaction from the equilibrium concentrations of the reactants and products and their balancing coefficients. At chemical equilibrium, the forward and reverse reactions proceed at equal rates, and the concentrations settle to a fixed ratio captured by the equilibrium constant. Kc is the product of the product concentrations, each raised to its coefficient, divided by the same for the reactants. Its value tells you which side the reaction favours: a large Kc means products dominate at equilibrium, a small Kc means reactants do, and a value near one means a balanced mixture. This is one of the central quantities in chemistry, used to predict the extent of reactions, design industrial processes, and understand acid-base and solubility behaviour. This tool computes it. You enter the equilibrium concentration and coefficient of up to two products and up to two reactants, leaving any unused species with a coefficient of zero, and the calculator returns Kc, the products term, the reactants term, and which side the reaction favours. The results update as you type. Use it for chemistry study, for equilibrium problems, or to judge how far a reaction proceeds. Each concentration is raised to the power of its coefficient from the balanced equation, the products multiplied together on top and the reactants on the bottom. Pure solids and liquids are conventionally left out, so enter only species in solution or gas phase. A reaction quotient calculated the same way from non-equilibrium concentrations, compared with Kc, tells you which way a reaction will shift to reach equilibrium. Kc has units that depend on the reaction, so it is often quoted as a plain number, and it is temperature-dependent, so it applies at the temperature the concentrations were measured.

Calculate.co.nz is proud to be partnered with realtor.co.nz, a trusted resource for navigating the New Zealand property market. Their Helpful Articles section offers clear, well-structured insights across buying, selling, and building, making complex real estate topics more accessible. With a focus on up-to-date guidance and practical knowledge, they empower Kiwis to move forward with clarity and confidence in a constantly evolving property landscape.

Kc = product concentrations^coefficients / reactant concentrations^coefficients. Set unused species coefficient to 0. Omit pure solids and liquids. Kc above 1 favours products.