pH, pKa, Henderson-Hasselbalch, and neutralization calculators. Browse our free acids & bases tools below — all calculators are instant, accurate, and require no sign-up.
Neutralization Reaction Calculator — Calculate volumes, concentrations, and heat of neutralization for acid-base reactions. Supports strong/strong, strong/weak, and polyprotic acid reactions with stoichiometry.
Henderson-Hasselbalch Calculator — Calculate buffer pH using the Henderson-Hasselbalch equation. Determine pH from pKa and concentration ratio, or solve for any variable. Includes buffer capacity and common buffer recipes.
pH Calculator — Calculate pH, pOH, [H⁺], and [OH⁻] from any one value. Includes strong/weak acid-base calculations, dilution, and a visual pH scale with common substance comparisons.
Gibbs Phase Rule Calculator — Calculate degrees of freedom using Gibbs Phase Rule (F = C - P + 2). Determine variance for any system with multiple components and phases, with interactive phase diagram examples.
pKa Calculator — Convert between pKa and Ka, calculate conjugate pKb, predict acid strength, and compare acid-base properties. Includes a database of common acids with pKa values and polyprotic acid support.
Two-Photon Absorption Calculator — Calculate two-photon absorption cross-sections, excitation wavelengths, action cross-sections, and fluorescence rates. Covers GM units, power density, and comparison of TPA fluorophores.