45 free tools across chemistry, physics, maths and accounts. Each has its own page and opens straight into the calculator.
Length, mass, temperature, pressure, energy, currency, GST and 17 more.
Relate a rate constant to temperature with k = A·e^(−Ea/RT): give any three of A, Ea (kJ/mol), T and k and solve for the fourth.
A plain calculator for everyday sums: add, subtract, multiply and divide, with percent and backspace keys.
Solve the Beer–Lambert law A = εlc for absorbance, molar absorptivity, path length or concentration — leave the one you want blank.
Enter the orbit number n and the atomic number Z to get the radius rₙ and the energy Eₙ of that Bohr orbit, for hydrogen or any hydrogen-like ion.
Find the pH of a buffer from its pKa and the concentrations of the conjugate base [A⁻] and the weak acid [HA], using the Henderson–Hasselbalch equation.
Balance a chemical equation: type the species with + between them and = or -> between the two sides, and get the balanced equation with its coefficients.
Relate vapour pressure to temperature with the Clausius–Clapeyron equation: from P₁ at T₁ and a second temperature T₂, solve for P₂ or for the enthalpy of vaporisation.
Use P₁V₁/T₁ = P₂V₂/T₂ for a fixed amount of gas: fill five of the six values, with temperatures in kelvin, and solve for the one you leave blank.
Add, subtract, multiply or divide two complex numbers written in the form a + bi.
Work out the molarity of a solution from the mass of solute, its molar mass and the volume of solution. Type a formula such as NaOH instead of a molar mass and the calculator finds it for you.
Find the electrostatic force between two point charges from F = kq₁q₂/r², with the charges in coulombs and the separation in metres.
Type a function and the limits a and b to evaluate the definite integral ∫ₐᵇ f(x) dx numerically.
Type a function and a point x = a to get the first and second derivatives f′(a) and f″(a) as numbers.
Solve M₁V₁ = M₂V₂ for whichever of the four values you leave blank — the standard way to plan a dilution from a stock solution.
Enter an element symbol or atomic number to get its ground-state electron configuration, with the element’s common oxidation states.
Find the real roots of f(x) = 0 inside a search range you choose.
Get the equivalent weight of a substance as its molar mass divided by its n-factor. Enter a formula or the molar mass directly.
Calculate force, kinetic energy, potential energy and work from whichever pairs of mass, acceleration, velocity, height, force and distance you know (g = 9.80665 m/s²).
Enter ΔH in kJ/mol, the temperature in kelvin and ΔS in J/mol·K to get ΔG = ΔH − TΔS, and with it whether the process is spontaneous at that temperature.
Compare the effusion rates of two gases with Graham’s law, r₁/r₂ = √(M₂/M₁). Enter each gas as a formula or as its molar mass.
Plot y = f(x) for any function of x — sin, cos, sqrt, log, exp, abs and ^ are understood — over the x range you set.
Solve PV = nRT for pressure, volume, amount or temperature: leave the unknown blank. Pressure is in atm, volume in litres and R = 0.08206 L·atm/mol·K.
Estimate income tax in India under the New Regime slabs for FY 2025-26 (AY 2026-27), with the ₹75,000 standard deduction for salaried people and pensioners, the §87A rebate and marginal relief.
Convert between the solubility product Ksp and the molar solubility s of a salt AₓBᵧ: enter x, y and either of the two values.
Solve the equations of uniformly accelerated motion: enter any three of u, v, a, t and s and the remaining two are worked out.
Evaluate lim x→a f(x) for a function you type, including limits at infinity (enter inf or -inf for a).
Fit a straight line y = mx + c to x, y pairs by least squares and get r² — the fit behind Arrhenius plots, calibration lines and rate-law data.
Convert between the mass and the amount of any substance: type its formula and either the mass in grams or the moles, and the other is calculated from the molar mass.
Type a 2×2 or 3×3 matrix, one row per line, and get its determinant, inverse and eigenvalues in one step.
Two modern-physics results in one tool: the de Broglie wavelength of a particle from its mass and velocity, and the energy of a photon from its wavelength.
Type any chemical formula — brackets and hydrates such as Ca(OH)2 or CuSO4.5H2O included — to get its molar mass and percentage composition by element.
Correct a standard electrode potential for real conditions: enter E°, the number of electrons n and the reaction quotient Q to get E = E° − (0.0592/n)·log Q at 298 K.
Enter any two of voltage, current and resistance to get the third from V = IR, together with the power dissipated.
Solve the lens or mirror formula for focal length, object distance or image distance in centimetres, using the sign convention — leave one value blank.
Type a formula, the element you are interested in and the overall charge, and get that element’s oxidation state by the standard rules (peroxides and hydrides are the known exceptions).
Calculate the number of permutations nPr and combinations nCr for any n and r up to n = 170.
Find every root of a polynomial from its coefficients, highest power first — for x³ − 6x² + 11x − 6 you would enter 1, −6, 11, −6.
Enter a principal quantum number n (1 to 8) to see its subshells, the number of orbitals in each, the total of n² orbitals and the 2n² electrons the shell can hold.
Radioactive decay with N = N₀(½)^(t/t½): leave any one of N₀, N, t or the half-life blank and it is calculated from the other three.
A copy-ready table of the constants chemistry numericals use: Avogadro, both values of R, Planck, the speed of light, the elementary charge, Boltzmann, Faraday, electron and proton mass, standard pressure, molar volume, Rydberg and ε₀. Tap a value to copy it.
Paste a list of numbers to get the count, mean, median, and both the population and the sample standard deviation.
Type a function and a point x = a to get the first five terms of its Taylor series about that point.
Use the van ’t Hoff equation to see how an equilibrium constant changes with temperature: from K₁ at T₁ and a second temperature T₂, solve for K₂ or for ΔH°.
Solve v = fλ for wave speed, frequency or wavelength from the other two. One button sets v to the speed of light for electromagnetic waves.
Enter any one of [H⁺], pH, [OH⁻] or pOH and get the other three, using pH + pOH = 14 at 25 °C.