Engineering Tools

Free electronics calculators for engineering and physics students, hobbyists and technicians. Identify components and work out circuit values in seconds.

Identify electronic components

Most small components do not have their value printed in full. Through-hole resistors use coloured bands, surface-mount resistors use short number and letter codes, and ceramic capacitors use a three-digit code in picofarads. The Resistor Colour Code Calculator, the SMD Resistor Code Calculator and the Capacitor Code Calculator turn these markings into values, and also work the other way round when you need to find a part.

Design and analyse circuits

Once you know your parts, the circuit calculators do the arithmetic. Use the Ohm's Law Calculator for voltage, current, resistance and power, the Series and Parallel Calculator to combine components, the Voltage Divider Calculator for reference voltages, the LED Resistor Calculator to protect LEDs, and the 555 Timer Calculator for oscillators and delays.

Solar, inverter and battery sizing

Planning backup power for a home, office or hostel? List your appliances once and the Solar System Calculator sizes the inverter, batteries, panels and charge controller for your city's sunshine. The Inverter Size Calculator and the Battery Backup Calculator answer the two questions people ask most: what size of inverter do I need, and how long will my batteries last?

Built for students

Every tool explains the formula it uses and includes worked examples, so you can check your own working for practicals, assignments and exams in physics and electrical or electronic engineering. Values can be typed the way engineers write them, such as 4k7 for 4.7 kΩ, 100n for 100 nF or 20mA for 0.02 A, and results use standard component values from the E12, E24 and E96 series where it matters.