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Chemistry Calculators

Solve chemistry homework with calculators for equations, stoichiometry, solutions, equilibrium, reaction rates, yields, thermodynamics, and more.

Updated September 1, 2026

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108 of 108 calculators shown

General chemistry calculators

Explore atoms, electron structure, bonding, chemical formulas, names, and core concentration relationships.

14 calculators available

Atom CalculatorFind the proton, neutron, and electron counts for an atom or ion from its atomic number, mass number, and signed charge.Atomic Mass CalculatorAdd protons and neutrons to find mass number, then convert that nucleon count from unified atomic mass units to kilograms.Average Atomic MassCalculate a weighted average atomic mass from isotope masses and percent abundances, with the abundance total checked before calculation.Bond Order CalculatorCalculate average Lewis bond order across equivalent positions or use bonding and antibonding electron counts for molecular orbitals.Chemical Name CalculatorName supported binary ionic compounds and common polyatomic-ion salts while showing the ions and oxidation-state check behind the answer.Effective Nuclear ChargeEstimate the nuclear charge felt by an occupied electron using the selected element, orbital, ground-state configuration, and Slater rules.Electron ConfigurationFind the full ground-state electron configuration, noble-gas shorthand, shell totals, and outer-shell electron count for any element.Electronegativity DifferenceCompare two Pauling electronegativity values, calculate their absolute difference, and see a clearly labelled classroom bond guide.Mass to Molar ConcentrationConvert mass concentration to molar concentration using a compound molar mass, with source and result units kept visible.Molar Mass CalculatorCalculate a compound’s molar mass from its chemical formula and review every element count, atomic weight, and mass contribution.Percent Composition CalculatorFind the mass percentage of every element in a compound from a parsed chemical formula and verify that the displayed shares total 100%.Percent Ionic CharacterEstimate percent ionic character from the Pauling electronegativity difference between two selected elements using the named empirical equation.pKa CalculatorCalculate pKa directly from a positive acid dissociation constant or rearrange Henderson–Hasselbalch values using a dimensionless base-to-acid ratio.Electron Configuration QuizPractice matching elements, ground-state electron configurations, and outer-shell electron counts with immediate explanations and a session score.

Stoichiometry calculators

Connect particles, moles, mass, composition, and balanced reaction quantities.

15 calculators available

Air-Fuel Ratio CalculatorCalculate stoichiometric and actual air–fuel mass ratios, lambda, and equivalence ratio for a fuel containing carbon, hydrogen, and oxygen.Atom Economy CalculatorCalculate reaction atom economy from balanced reactant coefficients and the desired product formula, with visible molar-mass contributions.Avogadro’s NumberConvert between amount of substance in moles and a count of atoms, molecules, ions, formula units, or other specified entities.Empirical Formula CalculatorConvert element masses or mass percentages into mole ratios and infer the smallest defensible whole-number empirical formula.Grams to Moles CalculatorConvert a measured mass to moles using either a supplied molar mass or a chemical formula with a calculated molar mass.Hydrogen Ion ConcentrationInterconvert pH, pOH, hydrogen-ion concentration, and hydroxide-ion concentration under the stated 25°C pKw assumption.Molality CalculatorCalculate solute molality from moles of solute and the mass of solvent, keeping solvent mass separate from total solution mass.Molarity CalculatorCalculate molarity from solute amount and solution volume, or derive the amount from solute mass and molar mass first.Molar Mass of GasEstimate a gas molar mass from measured mass, pressure, volume, and temperature using the ideal gas equation.Mole CalculatorFind moles from sample mass and molar mass or from a number of specified entities, then review equivalent mass and particle counts.Molecular Weight CalculatorCalculate dimensionless relative molecular or formula mass from a chemical formula and review every element contribution.Mole Fraction CalculatorCalculate each component mole fraction from amounts in moles or from component masses and molar masses, then verify the total is one.Moles to Atoms ConverterConvert moles to atoms or formula units and, for a supplied formula, calculate the atom count contributed by every element.Normality CalculatorCalculate normality from molarity and a reaction-specific equivalence factor supplied from the balanced chemical reaction.PPM to MolarityConvert mass-based ppm to molarity using the solution density and the solute molar mass, with every basis kept visible.

Mixtures and solutions calculators

Work with concentration, dilution, buffers, mixtures, titration, and water measurements.

22 calculators available

Activity CoefficientFind an activity coefficient from activity and normalized concentration, or estimate a single-ion value with the Davies equation.Alligation CalculatorFind the mixing ratio and optional source amounts needed to reach a target concentration between two compatible sources.Bleach Dilution CalculatorCalculate stock bleach volume and water to add for a lower target concentration while keeping the concentration basis consistent.Buffer CapacityEstimate differential buffer capacity for a monoprotic weak-acid/conjugate-base pair at a stated pH and total concentration.Buffer pH CalculatorCalculate acidic or basic buffer pH from a positive conjugate-pair ratio using the Henderson–Hasselbalch relationship.Concentration CalculatorCalculate molarity, mass concentration, mass percent, or volume percent in separate modes with matching quantities and units.Dilution FactorCalculate dilution factor from final and aliquot volumes or from stock and final concentrations using one named convention.Henderson-HasselbalchSolve buffer pH, pKa, conjugate-base amount, or weak-acid amount with a visible dimensionless ratio and logarithm.Mass Percent CalculatorSolve mass percent, component mass, or total mixture mass from two compatible values, with the denominator kept explicit.Mixing Ratio CalculatorTurn a two-part mass or volume ratio into component percentages and the amounts needed for a chosen total mixture.Neutralization CalculatorSolve one acid or base normality or volume from the equivalence relationship, with acid and base roles shown explicitly.Percentage to MolarityConvert mass percent by mass to molarity, or reverse the conversion, using solution density and solute molar mass.Percent Solution CalculatorCalculate percent, component amount, or final solution amount with separate mass/mass, mass/volume, and volume/volume definitions.pH CalculatorEstimate pH for a strong acid, strong base, or weak monoprotic acid while keeping each chemical model and assumption separate.Raoult's Law CalculatorCalculate each ideal-solution partial vapor pressure and the total from component mole fractions and pure-component pressures.Reconstitution CalculatorCheck the arithmetic relationship among dry amount, final liquid volume, and resulting concentration without replacing product instructions.Saponification ValueCalculate an oil or fat saponification value from blank and sample titres, titrant normality, and sample mass with the difference kept explicit.Serial DilutionPlan a repeated serial dilution from a fixed step factor or a target final concentration, with every tube concentration and volume shown.Solution DilutionSolve any one value in C1V1 = C2V2 and estimate the solvent volume needed to reach the calculated or entered final solution volume.TDS CalculatorAdd measured dissolved-ion concentrations or estimate total dissolved solids from electrical conductivity using a visible empirical factor.Titration CalculatorCalculate analyte concentration at equivalence from titrant concentration and volume, analyte volume, and balanced-reaction coefficients.Water HardnessConvert measured calcium and magnesium concentrations into hardness as CaCO3 and show each mineral contribution separately.

Chemical reactions calculators

Balance equations and examine yields, kinetics, equilibrium, and reaction quantities.

12 calculators available

Activation EnergyCalculate activation energy from two rate constants measured at two different temperatures using the two-point Arrhenius relationship.Actual YieldCalculate actual reaction yield from theoretical yield and percent yield while keeping the selected mass or amount unit unchanged.Arrhenius EquationSolve the Arrhenius equation for rate constant, pre-exponential factor, activation energy, or absolute temperature with visible logarithm checks.Equation BalancerBalance a molecular or explicitly charged chemical equation with exact coefficients and review the element-by-element conservation check.Equilibrium ConstantCalculate Kc from species concentrations, reaction sides, stoichiometric coefficients, and explicitly identified phases.Kp CalculatorConvert between Kc and Kp using temperature and the gaseous stoichiometric change Δn, with the convention shown beside the result.Molar RatioRead the directional mole ratio between two selected species from coefficients in a balanced chemical equation.Net Ionic EquationBalance a supported aqueous molecular equation, expand named strong electrolytes, cancel spectator ions, and audit mass and charge.Percent YieldSolve percent yield, actual yield, or theoretical yield while keeping both quantities in the same selected unit.Rate ConstantSolve a general rate law for reaction rate or rate constant from reactant concentrations and experimentally determined orders.Reaction QuotientCalculate Qc or Qp from current activities and stoichiometric coefficients, then optionally compare Q with K for direction.Theoretical YieldFind the limiting reactant and theoretical product amount from available reactant moles and balanced coefficients.

Chemical thermodynamics calculators

Study phase changes, energy, entropy, temperature effects, and ideal-gas conditions.

12 calculators available

Boiling PointFind boiling temperature from pressure using IAPWS-IF97 for water or bounded NIST Antoine correlations for ethanol and acetone.Boiling Point at AltitudeEstimate the boiling temperature of water from altitude with a standard-atmosphere pressure model and a bounded vapor-pressure correlation.Boiling Point ElevationCalculate how a dissolved solute raises a solvent’s boiling point from molality, van ’t Hoff factor, and solvent constant.EntropyCalculate entropy change using one clearly named mode: ΔS from ΔH and ΔG, reversible heat divided by temperature, or an ideal-gas isothermal change.Freezing Point DepressionCalculate how a dissolved solute lowers a solvent’s freezing point using molality, van ’t Hoff factor, and solvent constant.Gibbs Free EnergySolve ΔG = ΔH − TΔS for Gibbs energy, enthalpy, entropy, or temperature and interpret spontaneity only for the supplied conditions.Gibbs Phase RuleCalculate degrees of freedom from components and phases using the full or condensed Gibbs phase rule.Heat of CombustionCalculate released heat, amount of fuel, or molar heat of combustion with a deliberate sign convention and visible magnitude.Q10 Temperature FactorUse the empirical Q10 relationship to compare rates across temperatures or solve for a missing rate, temperature, or Q10 factor.STP CalculatorCalculate ideal-gas volume or amount at a named IUPAC or legacy standard temperature and pressure convention.Vapor PressureUse the integrated Clausius–Clapeyron relation to estimate a second vapor pressure or molar enthalpy of vaporization.Water Vapor PressureCalculate pure-water vapor pressure from temperature with a bounded NIST Antoine correlation and visible source interval.

Electrochemistry calculators

Calculate cell potential, electrolysis, ionic strength, and electrochemical relationships.

5 calculators available

Cell EMF CalculatorCalculate cell electromotive force from cathode and anode reduction potentials and relate it to molar Gibbs energy.Electrolysis CalculatorApply Faraday’s law to calculate deposited mass, electric current, or electrolysis time with explicit electron stoichiometry.Ionic StrengthCalculate solution ionic strength from editable ion concentration and signed integer charge rows.Lattice EnergyEstimate ionic-crystal lattice energy with an explicitly selected Born–Landé or Kapustinskii educational model.Nernst EquationCalculate an equilibrium cell potential from standard potential, temperature, reaction quotient, and electron count.

Physical chemistry calculators

Explore diffusion, decay, adsorption, osmotic pressure, gases, and surface effects.

9 calculators available

Diffusion CoefficientCalculate diffusion coefficient from mean-square displacement or estimate it with the Stokes–Einstein model.Rate of EffusionCompare gas effusion rates or solve a molar mass with Graham’s law using positive rates and molar masses.Half-Life CalculatorSolve exponential decay for remaining amount, elapsed time, or decay constant, or convert a decay constant directly to half-life.Langmuir IsothermCalculate fractional surface coverage or adsorbed capacity with the Langmuir single-site adsorption model.Osmotic PressureSolve the dilute ideal-solution relation Π = iMRT for osmotic pressure, molarity, temperature, or van ’t Hoff factor.Partial PressureCalculate gas partial pressure by Dalton mole fractions, the ideal-gas equation, or correction for collection over water.Radioactive DecayCalculate remaining nuclei and activity from an initial nuclei count, elapsed time, and half-life on one consistent time basis.Two-Photon AbsorptionEstimate per-molecule two-photon absorption rate and low-probability exposure from GM cross section and photon flux.Young-Laplace EquationCalculate pressure jump across spherical, cylindrical, or general curved interfaces, or estimate capillary rise.

Organic chemistry calculators

Check combustion, formula relationships, unsaturation, dating, and selected material properties.

8 calculators available

Chemical Oxygen DemandCalculate educational dichromate COD from blank and sample titration volumes, titrant normality, sample volume, and dilution.Combustion AnalysisFind a C–H–O empirical formula from sample mass and measured carbon dioxide and water, with an optional molecular-formula check.Combustion ReactionBalance complete combustion of a supported C–H–O fuel into oxygen, carbon dioxide, and water using smallest whole-number coefficients.Crude ProteinConvert a blank-corrected Kjeldahl titration into nitrogen percentage and crude protein with an explicit material-specific factor.Degree of UnsaturationCalculate degree of unsaturation from a neutral C/H/N/halogen formula and interpret the result as rings plus π bonds.Double Bond EquivalentFind the double bond equivalent of a neutral organic formula using carbon, hydrogen, nitrogen, and halogen counts.Liquid Ethylene DensityEstimate saturated liquid ethylene density and pressure from a bounded 2 K NIST table with four-point interpolation.Radiocarbon DatingEstimate C-14 decay age from remaining fraction or activity using the 5,730-year physical half-life or 5,568-year conventional BP convention.

Biochemistry calculators

Work through calibration, enzyme, protein, amino-acid, and oligonucleotide calculations.

6 calculators available

Calibration CurveFit a linear calibration curve to standard concentration and response pairs, report slope, intercept, R², residuals, and an unknown prediction.Enzyme ActivityInterconvert enzyme product rate, total activity, activity concentration, and specific activity in µmol/min, U, U/mL, and U/mg.Isoelectric PointEstimate the isoelectric point of any standard amino acid from an explicit educational pKa table and its neutral charge interval.Michaelis-Menten EquationSolve the one-substrate Michaelis–Menten equation for velocity, maximum velocity, substrate concentration, or Km.Protein SolubilityCalculate the named Kjeldahl-based soluble protein percentage from blank and sample titres, NaOH normality, and effective sample weight.Resuspension CalculatorSolve oligonucleotide amount, desired stock concentration, or solvent volume with common pmol, nmol, µmol, µM, mM, µL, and mL units.

Other calculators

Use light absorption, crystallography, and fluid-retention relationships.

5 calculators available

Beer-Lambert LawSolve absorbance, molar absorptivity, optical path length, or concentration with A = εbc and explicit unit conversions.Cubic Cell CalculatorRelate atomic radius and lattice constant for simple, body-centered, or face-centered cubic cells and estimate density from molar mass.Detention Time CalculatorSolve effective detention time, vessel volume, or average flow with an explicit usable-volume fraction and common engineering units.Hydraulic Retention TimeSolve reactor hydraulic retention time, liquid volume, or average flow with wastewater-facing labels and common unit conversions.Miller Indices CalculatorCalculate cubic interplanar spacing from lattice constant and integer Miller indices, with plane notation and index validation.

CHEMISTRY MADE CHECKABLE

Start with the question, keep the units, and review every step

Chemistry calculations become easier when each symbol is tied to a measurable idea. Atomic number counts protons, a chemical formula fixes element ratios, molar mass connects formulas to weighed samples, and stoichiometry connects moles to particles and balanced reaction amounts. These free chemistry calculators keep the selected values, formula, substitution, units, and answer together, making them useful for homework checks, revision, and everyday scientific estimates.

The directory follows ten chemistry topics: General chemistry calculators, Stoichiometry calculators, Mixtures and solutions calculators, Chemical reactions calculators, Chemical thermodynamics calculators, Electrochemistry calculators, Physical chemistry calculators, Organic chemistry calculators, Biochemistry calculators, and Other calculators. Each calculator remains a focused page so a search for a molar mass calculator, percent composition calculator, pKa calculator, Avogadro conversion, empirical formula, atom calculator, or electron configuration quiz reaches the exact inputs and explanation for that task.

Reference values are named and versioned

Element symbols, names, atomic numbers, and conventional atomic weights follow the IUPAC periodic table. Physical constants such as the atomic mass constant use NIST CODATA values. A source link appears on every chemistry calculator page so a learner can distinguish reference data from an equation entered by the site. Radioactive elements use the mass number shown for classroom reference rather than pretending that they have one natural standard atomic weight.

Models are named where the answer depends on a convention. Effective nuclear charge uses Slater rules, electronegativity comparisons use the Pauling scale, and bond order separates Lewis-resonance averaging from molecular-orbital electron counting. A result from one model is not silently presented as though every chemistry text or research method must return the same number.

Inputs are checked before a formula runs

Whole-particle fields reject fractions, isotope abundances must add to approximately 100 percent, an orbital must actually be occupied, and a chemical formula must use valid element symbols and balanced brackets. Empirical-formula ratios must be close to defensible small integers, while reaction metrics retain their balanced coefficients. These checks prevent an empty field from becoming zero and stop malformed or dimensionally incompatible inputs from producing a polished but meaningless answer.

Every successful calculation shows the formula and working below the main answer. Change any input and the old result disappears until the calculation is run again, so stale numbers are not left beside new values. Copy includes the answer and steps, while Reset restores a small example that can be used to understand the method before entering a homework problem.

Learning aids have honest limits

A correct classroom equation can still depend on an approximation. Nucleon-count atomic mass omits binding-energy detail, Slater shielding is not a high-accuracy quantum calculation, bond-type thresholds are guides rather than sharp boundaries, and a bounded ionic naming tool cannot name every acid, molecular compound, coordination complex, or organic structure. Unsupported cases are explained instead of being sent to an AI model for a guess.

Inputs and results remain in the current browser tab and are not uploaded for ordinary calculation. The tools are intended for students and general readers, not direct laboratory, medical, industrial, radiation, or safety-critical instructions. Keep the original question and units nearby, compare important results with a course reference or primary data source, and use the related calculators only when the next question genuinely requires a different formula.

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