Electrical Engineering
Ohm's Law Calculator
Solve Ohm's law for voltage, current, resistance or power — enter any two values and get all four.
V = I × R
Also called v=ir calculator · ohms law
Engineering · 10 calculators
Electrical Engineering Calculators
Ohm's law, single and three-phase power, voltage drop, transformer ratio, power factor, battery capacity and wire resistance.
Electrical Engineering
Electrical Power Calculator
Electrical power in watts from voltage, current or resistance, for DC and AC with power factor.
P = V × I × PF = I²R = V²/R
Also called watts calculator · power formula electrical
Electrical Engineering
Three Phase Power Calculator
Three-phase power, current and kVA from line voltage, current and power factor.
P = √3 × V_line × I_line × PF
Also called 3 phase power · three phase current
Electrical Engineering
Voltage Drop Calculator
Voltage drop along a cable run from length, conductor size and current, with the percentage drop.
V_drop = 2 × ρ × L × I / A (single phase)
Also called cable voltage drop · wire voltage loss
Electrical Engineering
Transformer Ratio Calculator
Turns ratio, secondary current and VA rating for a step-up or step-down transformer.
Vp / Vs = Np / Ns = Is / Ip
Also called turns ratio · step up transformer
Electrical Engineering
Power Factor Calculator
Power factor from real and apparent power, plus the capacitor kVAR needed to correct it.
PF = kW / kVA
Also called pf correction · kvar calculator
Electrical Engineering
Resistance Calculator
Resistance from voltage and current (R = V/I), in ohms.
R = V / I
Also called ohms calculator · find resistance
Electrical Engineering
Current Calculator
Electric current from voltage and resistance (I = V/R), in amperes.
I = V / R = P / V
Also called amps calculator · amperage
Electrical Engineering
Battery Capacity Calculator
Battery bank capacity in Ah and kWh for a required runtime, allowing for depth of discharge.
Ah = load W × hours ÷ efficiency ÷ DoD ÷ …
Also called battery bank size · ah calculator
Electrical Engineering
Wire Resistance Calculator
Resistance of a length of wire from its material, cross-section and temperature.
R = ρL / A
Also called cable resistance · conductor resistance
Key electrical engineering formulas
| Ohm's Law | V = I × R · P = V × I = I²R = V²/R |
|---|---|
| Electrical Power | P = V × I × PF = I²R = V²/R |
| Three Phase Power | P = √3 × V_line × I_line × PF |
| Voltage Drop | V_drop = 2 × ρ × L × I / A (single phase) |
| Transformer Ratio | Vp / Vs = Np / Ns = Is / Ip |
| Power Factor | PF = kW / kVA · kVAR = kW × (tan φ₁ − tan φ₂) |
| Resistance | R = V / I |
| Current | I = V / R = P / V |
| Battery Capacity | Ah = load W × hours ÷ efficiency ÷ DoD ÷ system V |
| Wire Resistance | R = ρL / A · R_T = R₂₀(1 + α(T − 20)) |
Electrical Engineering questions
What is Ohm's law in simple terms?
Current through a conductor is proportional to the voltage across it and inversely proportional to its resistance: I = V / R.