Engineering field
Electrical calculators and Ohm’s law
Ohm’s law, power and initial circuit quantities.
10 available calculators
Choose the appropriate calculation
Electricity
Ohm’s law, power and initial circuit quantities.
Essential electrical quantities
Connect voltage, current, resistance, power and energy with the fundamental relations.
- Ohm’s law and powerResistance, power and energy from U, I and t.
- Electricity cost calculator — power, time, kWh and costCalculate energy use from power and operating time, then apply your tariff per kWh. The cost result uses the same currency as the tariff you enter.
- Three-phase power, P–Q–S and currentCalculate P, Q and S from line-to-line voltage, line current and power factor, or solve current from kW or kVA.
- Single-phase power, P–Q–S and currentCalculate P, Q and S for a single-phase circuit from RMS voltage, RMS current and power factor, or solve current from kW or kVA.
- Power factor correction and reactive compensationFrom active power P and the initial and target power factors, calculate Q before and after correction, required compensation Qc, and the reduction in apparent power.
- Three-phase motor current — power, efficiency and power factorEstimate steady-state three-phase motor current from useful shaft power P₂, line-to-line voltage U, efficiency η and power factor.
- Transformer kVA, current and load sizingRelate transformer apparent power, voltage and current in single-phase or three-phase systems, or estimate required kVA from active load, power factor and a sizing margin.
- VFD frequency, motor speed and slipRelate electrical frequency, pole count, synchronous speed and shaft speed, with explicit slip for induction-motor operation.
- Single-phase / three-phase AC voltage dropCalculate AC cable voltage drop from the conductor linear resistance and reactance for single-phase or balanced three-phase circuits.
- Cable size from maximum voltage dropDetermine the conductor cross-section required to stay below a maximum voltage drop, then verify the drop with the selected preferred section.