Electrical & Electronics Calculators
From basic circuit analysis to solar panel sizing, our electrical and electronics calculators cover the essential computations for engineers, electricians, hobbyists, and students. Use Ohm's law to find voltage, current, resistance, and power. Decode resistor color bands, size LED current-limiting resistors, calculate capacitor values, determine proper wire gauge, and estimate electricity costs. All tools follow standard electrical engineering formulas and are free to use.
Circuit Fundamentals
Ohm's law, resistors, capacitors, and LED calculations.
Ohm's Law Calculator
Calculate voltage, current, resistance, and power from any two values.
Resistor Color Code Calculator
Decode 4, 5, or 6-band resistor color codes to find resistance.
LED Resistor Calculator
Find the right current-limiting resistor for your LED circuit.
Capacitor Calculator
Calculate capacitance, charge, energy, and time constants.
Wiring & Power
Wire sizing, cable sizing, power factor, electrical load, and transformers.
Wire Size Calculator
Determine the correct AWG wire gauge for your circuit.
Cable Size Calculator
Calculate cable cross-section for voltage drop and ampacity.
Power Factor Calculator
Calculate real, reactive, and apparent power in AC circuits.
Electrical Load Calculator
Estimate total electrical load for panel and circuit sizing.
Transformer Calculator
Calculate transformer turns ratio, voltage, and current.
Energy & Batteries
Battery life, solar battery sizing, and electricity cost estimation.
Frequently Asked Questions
How does Ohm's law work?
Ohm's law states that voltage (V) equals current (I) multiplied by resistance (R): V = I x R. If you know any two of these values, you can calculate the third. Our Ohm's law calculator also computes power (P = V x I), giving you all four key electrical values from any two inputs.
How do I read resistor color codes?
Resistor color bands represent digits and multipliers. Each color corresponds to a number (black=0, brown=1, red=2, etc.). For a 4-band resistor, the first two bands are digits, the third is the multiplier, and the fourth is the tolerance. Our resistor color code calculator decodes any 4, 5, or 6-band resistor instantly.
How do I choose the right wire size for my circuit?
Wire size depends on the current load, wire length, voltage, and acceptable voltage drop. Undersized wire can overheat and cause fires. Our wire size calculator uses NEC standards to recommend the appropriate AWG gauge for your circuit based on amperage, distance, and whether the installation is copper or aluminum.
What is power factor and why does it matter?
Power factor is the ratio of real power (watts) to apparent power (volt-amps) in an AC circuit. A power factor of 1.0 means all power is used efficiently. Low power factor wastes energy and can result in utility penalties for commercial users. Our power factor calculator helps you determine correction needs for motors and other inductive loads.