Chemistry calculations, not black-box answers
Free Chemistry Calculators
with Full Working
Stoichiometry, solutions, energetics, kinetics, equilibrium and experimental data — with the calculation steps between your values and the final answer.
6 calculators
Stoichiometry & gases
Move cleanly between mass, amount, particles, reacting ratios, yields and gas quantities.
Moles, mass & particles
Convert between mass, amount of substance and number of particles using molar mass and Avogadro’s constant, with full working.
Open calculatorEmpirical formula
Convert element masses or percentages into a simplest whole-number empirical formula, then optionally obtain a molecular formula.
Open calculatorLimiting reagent
Identify the limiting reactant from amounts in moles and stoichiometric coefficients, then calculate theoretical product amount.
Open calculatorPercentage yield
Calculate percentage yield from experimental and theoretical yield in matching units, with the substituted formula shown.
Open calculatorAtom economy
Calculate atom economy from a balanced equation using stoichiometric coefficients and molar masses.
Open calculatorIdeal gas equation
Solve PV = nRT for pressure, volume, amount or temperature using kPa, dm³, mol and K.
Open calculator4 calculators
Solutions & titration
Prepare, dilute and analyse solutions with concentration and titration calculations that show the mole logic.
Molar concentration
Solve n = CV for amount, concentration or solution volume with automatic cm³↔dm³ conversion.
Open calculatorStandard solution
Calculate the solute mass needed to prepare a standard solution from target concentration, volume and molar mass.
Open calculatorDilution
Solve the dilution relationship C₁V₁ = C₂V₂ for stock concentration, aliquot volume, final concentration or final volume.
Open calculatorTitration stoichiometry
Calculate an unknown concentration at equivalence from the known concentration, titre volumes and balanced-equation coefficients.
Open calculator5 calculators
Energetics & electrochemistry
Work through calorimetry, enthalpy cycles, bond enthalpies, Gibbs energy and electrochemical relationships.
Calorimetry
Calculate heat transferred and molar enthalpy from mass, specific heat capacity, temperature change and amount reacted.
Open calculatorBond enthalpy
Estimate reaction enthalpy from average bond enthalpies by summing bonds broken minus bonds formed.
Open calculatorHess / formation enthalpy
Calculate reaction enthalpy from standard enthalpies of formation using products minus reactants.
Open calculatorGibbs energy (HL)
Calculate standard Gibbs energy from enthalpy, entropy and temperature, or obtain an equilibrium constant from ΔG°.
Open calculatorE°cell & ΔG° (HL)
Calculate standard cell potential from cathode and anode reduction potentials, then convert E°cell to ΔG°.
Open calculator6 calculators
Acids, equilibrium & kinetics
Handle pH, equilibrium expressions, rates, orders and Arrhenius relationships with clear assumptions.
pH ↔ [H⁺]
Convert between pH and hydrogen-ion concentration using pH = −log₁₀[H⁺].
Open calculatorpH, pOH & Kw (HL)
Convert among pH, pOH, [H⁺] and [OH⁻] using a specified Kw, with no assumption that pKw must equal 14.
Open calculatorK or Q expression
Evaluate a concentration-based equilibrium expression from numerator and denominator concentration terms and exponents.
Open calculatorReaction rate
Calculate an average rate from a change over time, or the common inverse-time rate proxy used in clock-style experiments.
Open calculatorRate order (HL)
Determine an order with respect to one reactant from two initial-rate experiments, then estimate the corresponding rate constant.
Open calculatorArrhenius Eₐ (HL)
Use two rate constants at two temperatures to calculate activation energy and the Arrhenius pre-exponential factor.
Open calculator5 calculators
Experimental data & uncertainty
Paper 1B-friendly tools for calibration curves, uncertainty, significant figures and comparison of experimental values.
Calibration curve
Fit a linear calibration curve, report slope, intercept and R², and calculate an unknown concentration from its response.
Open calculatorPercentage uncertainty
Convert an absolute measurement uncertainty to percentage uncertainty and report a rounded x ± Δx result.
Open calculatorUncertainty propagation
Propagate school-lab uncertainties through addition, subtraction, multiplication and division; power propagation is clearly marked HL-only.
Open calculatorSignificant figures
Round a decimal or scientific-notation value to a chosen number of significant figures and explain which zeros carry meaning.
Open calculatorError & difference
Calculate percentage error against a reference, percentage difference between two measurements, or signed percentage change.
Open calculatorUseful for checking. Better for learning the logic.
Every calculator includes the relationship, defined variables, a worked example and common mistakes. Paper 1B pages focus on data analysis and experimental reasoning rather than reproducing examination questions.
Read the calculation conventions