EngineeringFormulaElectrical
Everything downstream of V = IR and P = VI.
Every electrical calculator here ultimately traces back to V = IR and P = VI, but the useful engineering questions rarely stop at the base relationship. Series & Parallel Resistance, Voltage Divider, and Voltage Drop apply that base relationship to real circuit topology and wire runs. Electrical Power, Single-Phase and Three-Phase Power, Power Factor, and Watts to Amps apply it to AC systems where real, reactive, and apparent power diverge. Battery Life and Capacitor Energy apply it to energy storage instead of steady-state flow.
Ohm's Law itself is still here as its own calculator, both because it's the most-searched entry point into this discipline and because every other electrical calculator on the site is honestly just a more specific version of it.
Electrical Calculators
23 tools- Ohm's Law CalculatorV = I × R
- Voltage Drop CalculatorVdrop = 2 × I × ρ × L / A
- Wire Gauge CalculatorRequired Ampacity = I × k, then select smallest gauge with Ampacity ≥ Required Ampacity
- Series & Parallel Resistance CalculatorRtotal = R1 + R2 + R3 + ...
- Electrical Power CalculatorP = V × I
- Voltage Divider CalculatorVout = Vin × R2 / (R1 + R2)
- Single-Phase Power CalculatorP = V × I × PF
- Three-Phase Power CalculatorP = √3 × VL × IL × PF
- Power Factor CalculatorPF = P / S
- Capacitor Energy CalculatorU = 1/2 C V²
- Battery Life Calculatort = C / I
- Amp Hour CalculatorAh = Wh / V
- Inductor CalculatorXL = 2 pi f L
- RC Time Constant Calculatorτ = R × C
- Watts to Amps CalculatorI = P / V
- kWh CalculatorDaily Energy = P × h / 1000
- Resistor Color Code CalculatorR = significant digits × multiplier
- LED Resistor CalculatorV_R = V_s − nV_f − V_driver
- Circuit Breaker Size CalculatorIreq = Inc + 1.25 × Ic, then choose the next standard breaker size ≥ Ireq
- Fuse Size CalculatorIreq = k × I, then choose the next standard fuse rating ≥ Ireq (k = 1.25 continuous, 1.0 intermittent)
- Diode CalculatorR = (V_s − V_F) / I
- Zener Diode CalculatorR_S ≤ (V_in,min − V_Z) / (I_L,max + I_Z,min)
- PCB Trace Width CalculatorW = [ I / (k ΔT^0.44) ]^(1/0.725) / t
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