63 FREE TOOLS · ϟ
Electrical calculators
Calculate ideal circuit relationships and electrical energy.
DC circuits & components
Explore resistance, capacitance, energy and simple circuit relationships.
Explore topic ↗24 calculatorsAC power & reactance
Calculate sinusoidal AC quantities, power factor and balanced three-phase power.
Explore topic ↗All electrical calculators
Ohms Law Current Calculator
Calculate ideal DC current from voltage and resistance.
Ohms Law Voltage Calculator
Find the voltage across an ideal resistor from current and resistance.
Ohms Law Resistance Calculator
Find ideal electrical resistance from voltage and current.
Electrical Power Calculator
Calculate DC electrical power from voltage and current.
Resistor Power Calculator
Calculate power dissipated as heat in a resistor.
Series Resistance Calculator
Add three resistors connected in series.
Parallel Resistance Calculator
Find equivalent resistance for two positive resistors in parallel.
Voltage Divider Calculator
Estimate unloaded output voltage from a two-resistor divider.
Battery Energy Calculator
Convert nominal battery voltage and amp-hours into nominal energy.
Battery Runtime Calculator
Estimate runtime from nominal battery energy, usable fraction and load power.
Ideal Battery Charge Time Calculator
Estimate the minimum constant-current time to replace a chosen capacity.
Capacitor Energy Calculator
Find stored energy in an ideal capacitor.
Series Capacitance Calculator
Find the equivalent capacitance of two ideal capacitors in series.
Parallel Capacitance Calculator
Add capacitances of two ideal parallel capacitors.
RC Time Constant Calculator
Calculate a resistor-capacitor circuit’s time constant.
RL Time Constant Calculator
Calculate the time constant of an ideal series resistor-inductor circuit.
Capacitive Reactance Calculator
Find capacitor reactance magnitude at a given sinusoidal frequency.
Inductive Reactance Calculator
Find ideal inductor reactance magnitude for sinusoidal AC.
LC Resonant Frequency Calculator
Find the ideal natural resonant frequency of an LC circuit.
AC Apparent Power Calculator
Calculate apparent power from single-phase RMS voltage and current.
Power Factor Calculator
Calculate real power divided by apparent power.
Three Phase Power Calculator
Estimate balanced three-phase real power from line voltage and line current.
RMS Sine Voltage Calculator
Convert peak amplitude of a pure sine wave to RMS voltage.
LED Series Resistor Calculator
Estimate resistance for a single LED from source voltage, forward drop and current.
Transformer Voltage Calculator
Find ideal secondary voltage from primary voltage and turns ratio.
Voltage Drop DC Calculator
Estimate resistive voltage drop using current and total loop resistance.
Wire Resistance Calculator
Estimate conductor resistance from material resistivity, length and area.
Resistivity Calculator
Recover resistivity from a uniform sample’s resistance and dimensions.
Resistance Temperature Calculator
Estimate resistance change from a supplied linear temperature coefficient.
Current Density Calculator
Find average electrical current per conductor cross-sectional area.
Electric Charge Calculator
Find charge transferred during a current flow interval.
Current From Charge Calculator
Calculate average current from total transferred charge.
Capacitor Charge Calculator
Find electric charge stored on an ideal capacitor.
Capacitor Charging Voltage Calculator
Estimate voltage during ideal first-order RC charging.
Capacitor Discharge Voltage Calculator
Estimate capacitor voltage after an ideal RC discharge interval.
Inductor Energy Calculator
Find magnetic energy stored in an ideal inductor.
Inductor Voltage Calculator
Find ideal inductor voltage from the rate of current change.
Series Inductance Calculator
Add two uncoupled inductors connected in series.
Parallel Inductance Calculator
Find equivalent inductance for two uncoupled parallel inductors.
Parallel Plate Capacitance Calculator
Estimate ideal capacitance from plate geometry and dielectric permittivity.
Battery Series Voltage Calculator
Find the nominal voltage sum for identical battery units in series.
Battery Parallel Capacity Calculator
Find the nominal amp-hour sum of an ideal compatible parallel battery bank.
Battery C Rate Calculator
Express charge or discharge current relative to battery capacity.
Inverter Input Current Calculator
Estimate inverter DC current from output load and assumed efficiency.
DC Converter Efficiency Calculator
Compare measured DC converter output and input power.
Resistor Colour Value Calculator
Decode a conventional resistor’s two digits and multiplier into resistance.
Single Phase AC Current Calculator
Find single-phase RMS current from real power, voltage and power factor.
Three Phase Current Calculator
Find line current for a balanced three-phase real-power load.
Reactive Power Calculator
Find reactive-power magnitude from compatible apparent and real power.
Power Factor Angle Calculator
Convert a sinusoidal displacement power factor into phase-angle magnitude.
Power Factor Correction Calculator
Estimate reactive compensation needed to raise an entered displacement power factor.
Series RLC Impedance Calculator
Find impedance magnitude for a series RLC circuit from component reactances.
Series RLC Phase Angle Calculator
Find the ideal voltage-current phase angle of a series RLC impedance.
RC Low Pass Cutoff Calculator
Find the minus-three-decibel cutoff of an ideal RC low-pass filter.
RL Filter Cutoff Calculator
Find the characteristic cutoff frequency of a simple RL filter.
Decibel Power Ratio Calculator
Express a power ratio as a decibel difference.
Decibel Voltage Ratio Calculator
Express a voltage amplitude ratio as a decibel difference.
Decibels to Power Ratio Calculator
Recover a linear power ratio from a decibel difference.
Decibels to Voltage Ratio Calculator
Recover a voltage amplitude ratio from a decibel difference.
Motor Synchronous Speed Calculator
Find synchronous rotating-field speed from frequency and pole count.
Induction Motor Slip Calculator
Compare rotor speed with a synchronous reference speed.
Motor Shaft Torque Calculator
Find shaft torque from mechanical power and rotational speed.
Transformer Secondary Current Calculator
Find ideal transformer secondary current from current and turns ratio.
Make your inputs count
These tools explain ideal electrical relationships. Real circuits involve component tolerances, temperature, conversion losses and protective requirements. Use manufacturer specifications for your equipment; a calculated value alone does not establish an installation rating.