Chemistry Calculators
Every result shows the formula, your substituted values, unit cancellation and assumptions — so you learn the working, not just copy an answer.
Atoms, Moles & Formulas
8 calculators
Molar Mass Calculator
M = Σ(nᵢCompute the molar mass of any compound from its formula — with per-element contributions, mass percentages, and the data source shown.
Grams ↔ Moles Converter
n = m / MConvert between mass and amount of substance using molar mass — enter a formula to look up M automatically, or supply your own.
Moles ↔ Particles Calculator
N = nConvert between amount of substance and the number of formula units, molecules, atoms or ions using the exact Avogadro constant.
Average Atomic Mass Calculator
Aᵣ = Σ(mᵢ × wᵢ)Weighted average of isotope masses — see exactly how each isotope contributes to the periodic-table value.
Isotope Abundance Calculator
xGiven two isotope masses and the average atomic mass, find the natural percentage of each isotope.
Percent Composition Calculator
%X = n_XBreak any formula into each element’s share of the mass, with every multiplication visible.
Empirical Formula Calculator
assume 100 g → n = m/Aᵣ → divide by smalTurn percent composition into the simplest whole-number atom ratio — assuming a convenient 100 g sample.
Molecular Formula Calculator
k = M(measured) / M(empirical); moleculaScale an empirical formula to the real molecule using the measured molar mass — multiplier shown and verified.
Reactions & Stoichiometry
7 calculators
Chemical Equation Balancer
conserve every element (and charge) — soBalance chemical equations and verify every atom with clear coefficients, worked steps, reaction guidance, and related practice.
Stoichiometry Calculator with Step-by-Step Solutions
n(known) → ×(ν_prod/ν_known) → n(target)Balance or validate the equation, convert moles, grams, particles, gases, and solution quantities with explicit units, molar ratios, and every conversion step.
Limiting Reactant Calculator with Steps and Yield
extent = n / ν — smallest extent ⇒ limitIdentify the limiting reagent, excess remaining, theoretical product yield, mole-ratio comparison, unit conversions, and full worked steps.
Excess Reactant Calculator
excess = n_initial − ν × extentHow much of the non-limiting reactant is left over after the reaction finishes.
Theoretical Yield Calculator
n_product = (n_limiting / ν_lim) × ν_proMaximum possible product mass from the limiting reactant — the benchmark for percent yield.
Percent Yield Calculator
% yield = (actual / theoretical) × 100 %Compare actual recovered product against the theoretical maximum.
Molar Ratio Calculator
ratio = νᵢ : νⱼ (GCD-reduced)Simplify balanced-equation coefficients into the whole-number mole ratio between any substances.
Solutions & Concentration
6 calculators
Molarity Calculator
c = n / VSolve c = n/V for any variable — or enter mass plus formula and let the tool find the moles for you.
Molality Calculator
b = n(solute) / m(solvent in kg)b = n / kg(solvent) — temperature-independent concentration for colligative work.
Dilution Calculator (c₁V₁ = c₂V₂)
c₁Solve dilution problems for any missing quantity — stock or diluted side.
Solution Preparation Calculator
m = cWeigh out exactly what you need: solute mass for a target molarity and final volume.
Mass/Volume/Amount Percent Calculator
% = (component / total) × 100 %w/w %, w/v % and v/v % — pick the right convention and see the units cancel correctly.
ppm / ppb Calculator
ppm = (m_solute / m_solution) × 10⁶ ≈ Trace concentrations by exact mass fraction — or the dilute-aqueous mg/L shortcut, clearly labeled as such.
Acids, Bases & Buffers
5 calculators
pH & pOH Calculator
pH = −log₁₀[H⁺]Convert between pH, pOH, [H⁺] and [OH⁻] — enter any one value and get the other three with the log algebra shown.
[H⁺] / [OH⁻] Concentration Calculator
[H⁺] = 10^(−pH); [OH⁻] = Kw/[H⁺]Dedicated reverse lookup: from any acid/base descriptor to both ion concentrations.
Weak Acid / Base Calculator
Ka = x²/(C−x) → x ≈ √(KaEquilibrium [H₃O⁺]/[OH⁻], percent ionization and pH for weak electrolytes — approximation checked against the quadratic every time.
Buffer pH Calculator (Henderson–Hasselbalch)
pH = pKa + log₁₀(n_base / n_acid)pH of a conjugate acid/base pair — moles or concentrations work equally since the volume cancels.
Acid–Base Titration Calculator
equivalence: n_acid = n_base; regions: epH at any point of a titration — equivalence volume plus before/equivalence/after logic for strong–strong and weak acid–strong base systems.
Gases
4 calculators
Ideal Gas Law Calculator (PV = nRT)
PV = nRTSolve PV = nRT for pressure, volume, moles or temperature — every input unit converted internally and shown.
Combined Gas Law Calculator
P₁V₁/T₁ = P₂V₂/T₂P₁V₁/T₁ = P₂V₂/T₂ — track a fixed gas sample between two states; solve any of the six variables.
Partial Pressure Calculator (Dalton’s Law)
P_total = ΣPᵢ; Pᵢ = xᵢSplit a total pressure among mixture components by mole fraction: Pi = xi·Ptotal.
Gas Density & Molar Mass Calculator
ρ = PM/(RT)ρ = PM/RT and its inverse — connect vapor density experiments with molar mass.
Energy, Equilibrium & Electrochemistry
8 calculators
Calorimetry Calculator (q = mcΔT)
q = mHeat absorbed or released by a temperature change — solve for heat, mass, specific heat or ΔT.
Specific Heat Calculator
c = q / (mDedicated c = q/(m·ΔT) solver — identify metals from measured heating data.
Hess's Law Calculator
ΔH_target = Σ kᵢCombine known reaction enthalpies — reversed steps flip signs; multiplied steps scale ΔH.
Gibbs Free Energy Calculator
ΔG = ΔH − TΔSΔG = ΔH − TΔS with automatic unit harmonization — spontaneity verdict included.
Equilibrium Constant & Reaction Quotient
Q = Π[products]^ν / Π[reactants]^ν (purK or Q from concentrations with correct exponents — pure solids and liquids excluded automatically.
Arrhenius Equation Calculator
k = ARate constants vs temperature — one-point form or two-temperature form solving k₂, Ea or T₂.
Nernst Equation Calculator
E = E° − (RT/nF)Cell potential under non-standard conditions — general form plus the exact 25 °C log-form coefficient.
Electrolysis Calculator (Faraday’s Law)
m = IMass deposited or gas produced from current and time: m = ItM/(zF).
Reference & Measurement
6 calculators
Radioactive Half-Life Calculator
N = N₀N = N₀·(½)^(t/T½) — solve for remaining amount, elapsed time or the half-life itself.
Density, Mass & Volume Calculator
ρ = m / Vρ = m/V solved in any direction — with unit-aware inputs and the triangle shown.
Chemistry Unit Converter
value × factor(from) ÷ factor(to)Convert between chemistry units with exact factors — pressure anchors like 1 atm = 101325 Pa are definitions, not approximations.
Temperature Converter
K = °C + 273.15K ↔ °C ↔ °F ↔ °R with affine formulas shown — and absolute-zero rejection built in.
Significant Figures Calculator
rules: nonzero countCount the significant figures in any measurement — and round it correctly, with every rule explained.
Oxidation Number Helper
Σ(states × atoms) = overall chargeAssign oxidation states by priority rules — free elements, ions, F/O/H conventions — and balance against total charge.
How shown working helps
- Formula with named variables and SI units
- Your substituted values and unit cancellation
- Assumptions (ideal gas, dilute solution, 25 °C …) labelled explicitly
- Precision chosen from YOUR inputs' significant figures — explained under each result
FAQ
- Are calculators free?
- Yes — no login required.
- Where do constants come from?
- Exact SI defining values; atomic weights from CIAAW 2021. Sources are versioned on every result.
- Why does an input sometimes show a red warning instead of an answer?
- The combination is physically impossible or ambiguous (e.g. below absolute zero). We explain why rather than guess.