Calculators
All calculators
Pick the calculator you need. New tools are added regularly.
Simple interest
Solve for capital, rate, periods or final amount when interest is not capitalised.
Equivalent simple rate
Convert a simple rate between monthly, quarterly, four-monthly and annual periods.
Compound interest
Solve for capital, rate, periods or final amount using the compound interest formula.
Equivalent compound rate
Convert a compound rate between frequencies with the exponential formula.
Annuity future value
How much you accumulate paying a constant instalment for n periods at a given rate.
Annuity present value
What a series of constant instalments you will receive in future is worth today.
Break-even point
Units and turnover needed to cover fixed costs, with contribution margin and margin of safety.
ROI (return on investment)
Net gain, percentage return and annualised return of an investment.
Savings goal
How much to set aside each month to reach a target amount by a given date.
Personal loan
Monthly payment, APR and total cost of a personal or car loan, with the repayment schedule.
Inflation and purchasing power
What money will be worth in the future, what a past sum is worth today, and the real return.
Bond yield
Gross and net yield to maturity, current yield and duration of a bond.
Regular investment plan
What a monthly investment in ETFs or funds grows to, after costs and tax.
Electricity usage and cost
How many kWh the appliances at home use and what they cost per day, month and year.
Mortgage payment
What you will pay each month, and what it costs in total.
Mortgage APR
The rate that includes the charges, and which one pushes it up.
How much can I borrow
Affordability: the instalment you can carry and the loan it buys.
Early repayment
What paying a lump sum off the capital is worth.
Variable-rate mortgage
Stress-test the instalment against a rising index.
Remortgaging
Compare the present mortgage with an offer from elsewhere.
Mortgage amortization schedule
Constant installment, full amortization table and a principal/interest chart.
Installment comparison
Comparison table: how the instalment changes as you borrow less or shorten the mortgage term.
Percentages
Percentage of a total, increases, discounts, percentage change and reverse percentage.
Derivatives
The derivative of a function and the rules used to get it.
Integrals
The antiderivative of a function and the definite integral between two limits.
Study of a function
Domain, sign, limits, asymptotes, turning points, concavity and graph, in one go.
Domain of a function
The conditions of existence and the domain written as intervals.
Limits
One-sided and two-sided limits, at a point or at infinity, with the indeterminate form.
Asymptotes
Vertical, horizontal and oblique asymptotes, with the limits that give them.
Descriptive statistics
Mean, median, mode, standard deviation, quartiles and frequency distribution.
Fractions
Addition, subtraction, multiplication and division of fractions, reduced to lowest terms.
Linear and quadratic equations
Roots, discriminant, vertex and factored form of ax² + bx + c = 0.
Synthetic division
Divides a polynomial by (x − a) and factors it.
Trigonometric formulas
Primary ratios, half-angle, double-angle, addition, prosthaphaeresis and Werner formulas on one or two angles.
GCD and LCM
Greatest common divisor and least common multiple with prime factorization.
Proportions
Missing term, fourth proportional, geometric mean and third proportional.
Combinatorics
Factorial, permutations, arrangements, combinations and the binomial coefficient.
Inequalities
Linear and quadratic inequalities by sign analysis.
Logarithms and exponentials
Logarithm in any base, exponential equations and change of base.
Radicals
Simplifying roots and rationalising denominators.
Probability
Classical and conditional probability, Bayes and the binomial distribution.
Sequences
Arithmetic and geometric sequences, nth term and sums.
Grade average
Simple and weighted averages, and the mark needed for a target.
Complex numbers
Operations, rectangular, polar and exponential form, powers and n-th roots, with the Argand diagram.
Prime factorisation
Prime factors of a number up to 30 digits, with the division ladder, divisors and a primality test.
Factoring polynomials
Common factor, the factor theorem, special products and quadratics: factoring a polynomial step by step.
Repeating decimal to fraction
From a recurring decimal to a fraction and from a fraction to a decimal, with the repeating block and the rule explained.
Scientific notation
Scientific and engineering notation, significant figures and rounding of any number.
Differential equations
First and second-order linear differential equations with constant coefficients, with solution and graph.
Perimeter and area
Perimeter, area and derived measurements for nine plane figures, from the square to the ellipse.
Volume and surface
Volume, total and lateral surface of seven solids, with slant height and diagonal.
Pythagorean theorem
The missing hypotenuse or leg, with area, perimeter, angles and Euclid's theorems.
Triangle solver
Solve any triangle from three measurements, ambiguous case included.
Arc and sector of a circle
The parts of a circle: arc, chord, sagitta, sector and circular segment.
Matrices and vectors
Addition, product, determinant, transpose, dot product and magnitude for matrices and vectors.
Vector mathematics
Dot and cross products, the angle between two vectors, projection and areas.
Determinant and inverse
Determinant, rank and inverse of a square matrix up to 12 × 12.
Systems of linear equations
Gauss-Jordan elimination: unique solution, infinitely many solutions or no solution.
Eigenvalues and eigenvectors
Characteristic polynomial, real and complex eigenvalues, eigenvectors and trace.
Line through two points
Equation of the line in slope-intercept and standard form, slope and intercepts.
Distance and midpoint
Distance between two points in the coordinate plane and coordinates of the midpoint.
Conic sections
Identifies the conic from its general equation and finds centre, foci, axes, eccentricity, asymptotes and canonical form.
Motion and projectiles
Uniform and uniformly accelerated motion, free fall and launch at an angle.
Dynamics and Newton's laws
Second law, weight, friction, inclined plane, centripetal force and impulse, with the formula inverting itself.
Collisions and momentum
Head-on collisions, elastic, inelastic and in between: final velocities, energy lost and impulse exchanged.
Rotational dynamics
Moment of inertia, the parallel axis theorem, torque, angular momentum and rolling, with the formula that rearranges itself.
Universal gravitation
Newton's law, surface gravity, orbital and escape speed, Kepler's third law and gravitational potential energy.
Oscillations and harmonic motion
Mass on a spring, simple pendulum, maximum speed and acceleration, oscillator energy and damping, with the motion plotted.
Error propagation
The uncertainty of a quantity computed from any formula, in quadrature and as a maximum error, and the mean of repeated readings with its error.
Linear regression
The least-squares line with the uncertainties of slope and intercept, weighted when you have σ, correlation coefficient and χ², with the plot.
Work, energy and power
Kinetic, potential and elastic energy, work, power and momentum.
Ohm's law
Voltage, current, resistance, power dissipated and series and parallel resistors.
Resistor colour code
Value and tolerance of a resistor from 4, 5 or 6 colour bands.
Kirchhoff's laws
Conductor resistance, real sources and DC dividers.
Coulomb's law and the electric field
Force between charges, field, potential and electrostatic energy, with the formula reversible on every quantity.
Gauss's law
Flux, enclosed charge and fields with spherical, cylindrical and planar symmetry.
Capacitors
Capacitance, charge, voltage and energy, the parallel-plate capacitor and the equivalent capacitance in series and parallel.
Magnetic field and Lorentz force
Force on charges and wires, the field of a wire, a loop and a solenoid, radius of curvature and cyclotron frequency.
Electromagnetic induction
Flux, the Faraday-Lenz law, motional emf, the inductance of a solenoid and the energy in a coil.
RLC circuits and alternating current
Reactances, impedance, resonant frequency, power factor and the RC and RL time constants.
Poles and zeros
The poles, zeros and stability of a transfer function.
Bode plot
Magnitude, phase and stability margins of H(s).
Pressure loss
Friction and fitting losses along a pipe.
Voltage drop
Cable voltage drop and the section it needs.
Beam bending
Bending moment, stress and deflection of a beam.
Electromagnetic waves and optics
Wavelength and frequency, photon energy, Snell's law, intensity and interference fringes.
Refraction and Snell's law
Angle of refraction, critical angle and total internal reflection, with a draggable ray diagram.
Lenses and mirrors
Geometrical optics: focal length, image distance, magnification and optical power.
Polarisation and diffraction
Wave optics: Malus, Brewster, diffraction, resolving power and interference.
Mechanical waves
String speed, sound in air, Doppler, beats and sound level.
Fluid statics
Hydrostatic pressure, Pascal, Archimedes and floating.
Fluid dynamics
Flow rate, Bernoulli, Torricelli, Venturi and viscous flow.
Calorimetry
Heat, equilibrium temperature, expansion and heat loss.
Thermodynamics
First law, work done by a gas, adiabatics and efficiency.
Periodic table
All 118 elements, searchable by name, symbol or atomic number, each with its full record.
Molar mass
Molar mass from a chemical formula with percentage composition.
Moles
Conversion between grams, moles, particles and volume of gas.
Concentration and dilution
Molarity, molality, percentages, ppm and dilution M₁V₁ = M₂V₂.
pH and pOH
pH, pOH and the concentrations of H⁺ and OH⁻ ions.
Ideal gas law
The equation of state PV = nRT and transformations between two states.
Chemical equation balancer
Balance any chemical equation, ionic and redox included, with the smallest coefficients and an atom-by-atom check.
Stoichiometry and limiting reagent
Limiting reagent, theoretical and percentage yield and excess reactants from grams or moles.
Number base converter
Binary, octal, decimal, hexadecimal and two's complement.
Boolean algebra
Truth table of a logical expression with AND, OR, NOT and XOR.
Base64 converter
From text, integer, hexadecimal or binary to Base64 and back, with the 6-bit groups explained.
IPv4 subnet calculator
Network, broadcast, usable hosts and masks from an IPv4 address with a CIDR prefix.
Hash generator
MD5, SHA-1, SHA-256, SHA-384 and SHA-512 of a text or of bytes, with a hash checker.
Unix timestamp converter
From Unix timestamp to date and time and back: seconds, milliseconds, UTC and local time.
Data size and download time
From bytes to gigabytes and gibibytes, and how long a file takes to download at a given speed.
Bitwise operations
AND, OR, XOR, NOT, shifts and rotations on 8, 16, 32 or 64-bit integers, with the bits on show.
IEEE 754 floating point
How a decimal is stored as a 32 or 64-bit float: sign, exponent, mantissa and the error.
Unicode and UTF-8 codes
The code point, UTF-8 and UTF-16 bytes and HTML code of every character, emoji included.
Colour converter
From HEX to RGB, HSL, HSV and CMYK and back, with the WCAG contrast of white and black text.
Password strength checker
Entropy in bits and time to guess it, with weak patterns recognised. Nothing leaves the browser.
URL encoder and decoder
Percent-encoding and decoding of values and addresses, and a URL taken apart into its pieces.
Regex tester
Test a regular expression on text: highlighted matches, capture groups and replacement, in JavaScript.
JSON formatter and validator
Format, minify and validate JSON: indentation, sorted keys and the exact position of errors.
Cron expression explainer
Turn a cron expression into words and see the next runs, field by field.
CRC32 and Adler-32 checksums
CRC-32, CRC-32C, four CRC-16 variants, CRC-8, Adler-32 and Fletcher-16 of text or hex bytes.
IPv6 subnet calculator
Network, address range, compressed and expanded forms, reverse DNS and splitting of an IPv6 prefix.
VAT calculator
Add or remove VAT, with the common statutory rates one tap away.
Markup and margin
Selling price from cost and markup or margin, with both figures.
Proportional allocation
Dividing an amount into proportional parts, directly or inversely.
Asset depreciation
Depreciation schedule by straight line or declining balance, year by year.
Financial ratios
ROE, ROI, ROS, gearing and liquidity ratios.
Accruals and deferrals
Accrued or deferred, income or expense: the share for the year and the year-end journal entries.
NPV and IRR
Net present value, internal rate of return and payback period of an investment.
Current account interest
Daily-balance interest on a current account: credit and debit products, tax and closing balance.
Bill discounting
Bank discount, true discount and compound discount, net proceeds and effective rate of a discounted bill.
Late payment interest
Interest on an invoice or a debt paid late, from the days overdue and the rate.
Contribution margin
Unit and total contribution margin, break-even point, margin of safety and operating leverage.
Economic order quantity
The order size that minimises costs (Wilson formula), orders per year, costs and reorder point.
Unit converter
Ten categories of units, from length to pressure, with a full conversion table.
Days between dates and age
Days, weeks and months between two dates, weekdays, exact age and the date after a number of days.
Roman numerals
Convert numbers to Roman numerals and back, with the symbol-by-symbol breakdown.