Engineering Calculators

Enter any two of voltage, current, resistance and power — get all four instantly.

Work out a load's kWh consumption and monthly cost — DC, single-phase or three-phase AC.

Read any resistor's value from its colour bands — 4 or 5 bands, with tolerance range and a live diagram.

Combine any number of resistors in series or parallel into one equivalent value.

Check the voltage drop along a cable and the minimum cross-section that keeps you within limits.

Output voltage of a two-resistor divider — including the effect of a load.

Size the series resistor that drives an LED safely — with the nearest standard value.

Decode a printed capacitor code (104 · 4n7 · 220) into every unit.

Read an SMD resistor from its marking — 3/4-digit, R-notation and EIA-96.

Capacitive and inductive reactance at a frequency — and the LC resonant frequency.

The −3 dB cutoff of a simple filter — and the attenuation at a frequency you pick.

The trace width a current needs per IPC-2221 — with resistance, voltage drop and dissipation.

Convert a resistor network between star (Y) and delta (Δ) connections in one step.

Instantly convert metre, kilometre, centimetre, inch, foot, mile and every length unit.

Convert between kilogram, gram, tonne, pound, ounce and every mass unit.

Convert between Celsius, Fahrenheit, Kelvin and Rankine — with the correct offset.

Convert square metre, hectare, dunam, feddan, acre, square foot and more.

Convert litre, cubic metre, gallon (US/UK), cubic foot and oil barrel.

Convert pascal, bar, psi, atmosphere, mmHg and kgf/cm².

Convert joule, kilowatt-hour, calorie, BTU and electronvolt.

Convert watt, kilowatt, horsepower (mechanical & metric) and BTU/hour.

Convert newton, kilogram-force, pound-force and dyne.

Convert newton-metre, kgf·m, lbf·ft and lbf·in.

Convert km/h, m/s, mph, knot and Mach.

Convert degree, radian, gradian, turn, arcminute and arcsecond.

Convert bit, byte, kilobyte, megabyte — decimal (10ⁿ) and binary (2ⁿ).

Convert second, minute, hour, day, week, year and millisecond.

Convert hertz, kilohertz, megahertz, rev/minute (rpm) and rad/second.

Convert m³/hour, litre/second, gallon/minute and CFM.

A full scientific calculator: trig, logs, powers and roots, parentheses and memory — with a live result as you type.

Convert an integer between decimal, binary, octal and hexadecimal — with complement form for negatives.

Five common percentage operations: percent-of, what-percent, percent-change, and add or subtract a percent.

Solve the proportion a/b = c/d — enter any three and get the fourth.

Roots of ax²+bx+c=0 — real or complex — with the discriminant and the parabola vertex.

Solve a₁x+b₁y=c₁ and a₂x+b₂y=c₂ by the Cramer rule.

Enter two sides of a right triangle (legs a, b and hypotenuse c) to get the third side, the angles and the area.

From a list of numbers: mean, median, range, variance and standard deviation (sample and population).

Determinant, trace and inverse of a 2×2 matrix.

Area, circumference and diameter of a circle from its radius.

Area, perimeter and diagonal of a rectangle from its sides.

Area (Heron formula) and perimeter from the three side lengths.

Area of a trapezoid from its two parallel sides and height.

Area, perimeter and angles of a regular polygon from side count and length.

Area and approximate perimeter of an ellipse from its semi-axes.

Volume, surface area and space diagonal of a box from its dimensions.

Volume, lateral and total surface area of a cylinder from radius and height.

Volume and surface area of a sphere from its radius.

Volume, slant height and surface area of a cone from radius and height.

Wall volume, inner capacity and cross-section of a pipe from its outer/inner diameters and length.