Resistor color codes, LED resistors, capacitor codes, Ohm's law, power and voltage drop, with the formula behind every result.
5 of 5 tools
These tools handle the math that comes up when building or repairing a circuit: reading resistor bands, finding the standard value that fits, decoding the number printed on a capacitor and working out how much current a device draws. You can type values the way people write them on the bench: 4k7, 100n, 2R2.
Everything runs in the browser and every result shows the formula used, so you can check it. They do math, not design: the electrical installation of a building follows technical standards and calls for a qualified professional.
The Resistor Color Code reads 3 to 6 bands and also works in reverse, from value to colors, showing the nearest value in the E12, E24 and E96 series. The LED Resistor Calculator always rounds up, since rounding down passes more current than calculated. The Capacitor Code tool reads markings such as 104 (100 nF) and 4n7 and converts between pF, nF and µF.
The Watts, Amps and Volts Calculator solves Ohm's law from any two values and power in single, two and three-phase circuits, with power factor and kVA. The Voltage Drop Calculator applies cable physics from material, size, length and current, and compares sizes side by side for the limit you choose.
No. They calculate current, power and voltage drop, which are part of the math, but sizing an installation also takes ampacity, installation method and protection into account according to technical standards. For that, consult a qualified professional.