Core formulas, phase power, resistance, circuits, and units
kW, kVA and Amp Calculator
Choose kVA to amps, amps to kW, or kW to amps and see only the inputs required for that calculation.
Open calculatorElectrical Fundamentals & Circuit Analysis
Everyday calculators for voltage, current, resistance, power, energy, passive circuits, power factor, and electrical units.
17 calculatorsCore formulas, phase power, resistance, circuits, and units
Three Phase Current Calculator
Calculate three-phase current from kW or kVA, line voltage, power factor, and efficiency.
Open calculatorCore formulas, phase power, resistance, circuits, and units
Power Factor Calculator and Correction
Analyze active, reactive, and apparent power or calculate the capacitor-bank kvar needed to improve power factor.
Open calculatorCore formulas, phase power, resistance, circuits, and units
RC Circuit and Time Constant Calculator
Calculate RC time constant, cutoff frequency, charging and discharging voltage, capacitive reactance, impedance, gain, and phase at one frequency.
Open calculatorCore formulas, phase power, resistance, circuits, and units
RLC Impedance and Resonance Calculator
Calculate series or parallel RLC reactance, impedance, admittance, current, phase angle, power factor, resonance frequency, and Q factor.
Open calculatorCore formulas, phase power, resistance, circuits, and units
Current Divider Calculator
Split a known total current across two to six parallel resistive branches and calculate equivalent resistance, common voltage, branch current, and branch power.
Open calculatorCore formulas, phase power, resistance, circuits, and units
Capacitor Reactance and Energy Calculator
Calculate capacitive reactance, RMS current, stored energy, charge, peak current screen, and series or parallel equivalent capacitance.
Open calculatorCore formulas, phase power, resistance, circuits, and units
Inductor Reactance and Energy Calculator
Calculate inductive reactance, RMS current, stored magnetic energy, time constant, and series or parallel equivalent inductance.
Open calculatorCore formulas, phase power, resistance, circuits, and units
Current Shunt Calculator
Size or verify a DC current shunt from rated current and millivolt drop, including resistance, power loss, burden voltage, and meter scaling.
Open calculatorCore formulas, phase power, resistance, circuits, and units
Three-Phase Power Calculator
Calculate balanced three-phase active power, apparent power, reactive power, current, phase angle, and power-factor improvement effects.
Open calculatorCore formulas, phase power, resistance, circuits, and units
Power, Energy & Time Calculator
Enter any two of power, energy, and operating time to calculate the third with automatic electrical-unit conversion.
Open calculatorCore formulas, phase power, resistance, circuits, and units
Voltage Divider Calculator with Load
Calculate a two-resistor voltage divider, solve for either resistor, or include load resistance to quantify output error and resistor power.
Open calculatorCore formulas, phase power, resistance, circuits, and units
PCB Conductor Spacing Calculator
Estimate a PCB conductor-spacing reference from voltage and conductor environment, or calculate the maximum reference voltage for an available spacing.
Open calculatorCore formulas, phase power, resistance, circuits, and units
Ohm's Law Calculator
Enter any two of voltage, current, resistance, and power to calculate the other two electrical quantities.
Open calculatorCore formulas, phase power, resistance, circuits, and units
Watts to Amps and Volts Calculator
Convert watts, amps, and volts for DC, single-phase, or three-phase systems with common voltage presets.
Open calculatorCore formulas, phase power, resistance, circuits, and units
Series and Parallel Resistor Calculator
Calculate equivalent resistance, current, and voltage or current division for up to four resistors.
Open calculatorCore formulas, phase power, resistance, circuits, and units
Electrical Unit Converter
Convert power and energy units in either direction, or calculate DC, single-phase, and three-phase current from power.
Open calculatorStart with the electrical quantities you know
Electrical fundamentals connect voltage, current, resistance, power, energy, time, and power factor. These quantities are the starting point for nearly every downstream cable, breaker, motor, transformer, battery, and control-panel decision.
The calculators in this category keep units and system type visible so a DC relationship is not accidentally mixed with single-phase or balanced three-phase assumptions.
From a known value to an engineering input
The most useful calculator is the narrowest one that matches the question. Ohm's law suits V-I-R relationships, power calculators distinguish kW from kVA, and circuit tools address divider ratios or passive networks.
A mathematically correct result is not automatically an equipment rating. Treat it as a transparent intermediate value, then continue to the relevant protection, conductor, thermal, or product-selection check.
Applications
Where these calculators fit
Load conversion
Translate nameplate power, voltage, efficiency, and power factor into operating current.
Circuit analysis
Review resistor networks, voltage division, impedance, energy, and time relationships.
Input verification
Cross-check measured or specified quantities before equipment sizing begins.
FAQ
Which electrical calculator should I start with?
Start with the quantity you need to find and the values you already know. Use Ohm's law for voltage, current, and resistance; a power calculator for watts, VA, or power factor; and a dedicated circuit calculator for networks or time-dependent behavior.
Why do AC results differ from DC results?
AC calculations may require RMS values, phase arrangement, power factor, and impedance. DC calculations generally use steady voltage and current without a phase factor.
Can a formula result select a breaker or cable directly?
No. The calculated current becomes an input to breaker, cable, voltage-drop, fault, and installation checks.
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