⬡ The Online Toolkit
Tools and Digital Instruments for Scientists
The Online Toolkit is a free collection of science calculators and reference tools built for scientists, students, researchers, and educators. Use the tools below to solve common problems in organic, inorganic, analytical and physical chemistry, thermodynamics, engineering, physics and more, forever free.
Periodic Table
Investigate the elements, including atomic numbers and weights, electron configurations and other properties.
Spectrochemical Series
Explore the relative strengths of ligands in crystal field theory and coordination chemistry.
Mole Calculator
Convert between mass and moles, with searchable molar masses by element names or symbols.
Molarity & Dilution
Calculate solution concentrations and solve dilution equations (C₁V₁ = C₂V₂).
Molality Calculator
Determine molal concentrations based on solute moles or mass, and solvent masses.
Empirical Formula
Find empirical and molecular formulas from elemental percentage composition or mass data.
pH Calculator
Calculate pH, pOH, [H⁺], and [OH⁻] for strong/weak acids, bases, and buffer solutions.
Concentration Converter
Interconvert molarity, ppm, ppb, % w/v, % w/w, mg/dL, g/L and more with unit-aware conversions.
Ideal Gas Law
Solve for pressure, volume, moles, or temperature in PV = nRT with flexible unit selection.
Raoult's Law
Calculate vapour pressures of mixtures, boiling point elevation, and freezing point depression.
Arrhenius Calculator
Solve for rate constant k, activation energy Ea, or pre-exponential factor A. Compare rates at two temperatures.