Electrical Calculators
Practical tools for voltage, current, resistance, power, voltage drop and conductor estimates.
Voltage Drop Calculator
Estimate voltage drop from current, distance and copper wire size.
Open calculator →ElectricalWire Size Calculator
Estimate copper wire gauge from load current.
Open calculator →ElectricalOhm's Law Calculator
Calculate voltage, current, resistance and power.
Open calculator →ElectricalResistor Color Code Calculator
Decode 4-band and 5-band resistor colors or generate color bands from resistance.
Open calculator →ElectricalSeries & Parallel Resistor Calculator
Calculate equivalent resistance for multiple resistors connected in series or parallel.
Open calculator →ElectricalVoltage Divider Calculator
Calculate Vout, Vin, R1 or R2 for a two-resistor voltage divider.
Open calculator →ElectricalPower Factor Calculator
Calculate power factor, kW, kVA, kVAR and phase angle from the AC power triangle.
Open calculator →ElectricalPower Factor Correction Calculator
Calculate capacitor kVAR needed to improve power factor and compare current before and after correction.
Open calculator →ElectricalTransformer Calculator
Calculate transformer primary and secondary full-load current from kVA and rated voltages.
Open calculator →ElectricalSeries & Parallel Capacitor Calculator
Calculate equivalent capacitance for capacitors in series or parallel, with optional charge, energy and voltage distribution.
Open calculator →ElectricalRC Time Constant Calculator
Calculate RC time constant, capacitor charging or discharging voltage, current, target time and cutoff frequency.
Open calculator →ElectricalBattery Runtime Calculator
Estimate battery runtime from capacity, voltage, load and efficiency.
Open calculator →ElectricalAmps to Watts Calculator
Convert electrical current in amps to watts.
Open calculator →ElectricalWatts to Amps Calculator
Convert electrical power in watts to current in amps.
Open calculator →ElectricalElectricity Cost Calculator
Calculate appliance kWh usage and daily, monthly and yearly electricity cost.
Open calculator →Helpful Guides
Go beyond the calculator with practical explanations, formulas and worked examples.
Ohm's Law Explained: Voltage, Current and Resistance
Learn how Ohm's Law connects voltage, current and resistance, with formulas, rearrangements and practical calculation examples.
ElectricalWatts, Amps and Volts Explained
Understand watts, amps and volts, how they relate through electrical power formulas, and how to convert between them.
ElectricalHow to Calculate Voltage Drop
Learn what voltage drop is, how conductor resistance and current affect it, and how to estimate voltage drop and percentage drop.
Electrical formulas and planning estimates
Electrical calculators cover Ohm's law, current and power conversion, voltage drop and simplified wire-size estimation. They are useful for learning, checking arithmetic and making preliminary comparisons between electrical values.
Choosing the right calculator
Use the Ohm's Law Calculator for voltage, current, resistance and power relationships. Use Amps to Watts or Watts to Amps for power conversion, and use Voltage Drop or Wire Size only as preliminary planning tools before checking the applicable electrical requirements.
- Use the correct voltage, phase and power factor for AC calculations.
- Treat simplified wire-size and voltage-drop results as estimates, not code approval.
- Use qualified electrical guidance for safety-critical design or installation decisions.