Electrical and Engineering
Calculate Ohm's law, resistor color codes, power consumption, voltage dividers, and LED resistors.
Electrical and Engineering tools
Which Electronics Calculator Fits Your Circuit?
Start with the Ohm's Law Calculator for any basic circuit. Enter two of voltage, current and resistance, and it finds the third. For example, 12 V across a 6 ohm load draws 2 A. Most of the other tools here build on that one rule.
When you pick parts, the Resistor Color Code Calculator reads 4, 5 and 6-band resistors. The LED Resistor Calculator finds the resistor value and wattage an LED needs for your supply. For example, a red LED that drops 2 V on a 5 V supply at 20 mA needs 150 ohms. The Voltage Divider Calculator gives the output voltage of two resistors in series.
For wiring, the Wire Gauge Converter turns AWG sizes into millimeters and shows copper resistance. To estimate running costs, the Power Consumption Calculator turns an appliance wattage and daily hours into kilowatt-hours and cost. A 100 W device that runs for 10 hours uses 1 kWh.