Calculators

Electrical Calculators

The calculations you run every day, with the formula shown and results you can save. Every answer is voltage-drop or first-principles math — always verify against the wiring regulations for your installation before you rely on it.

Ohm's Law

Fill any two fields — the third is calculated automatically.

Voltage (V)

Current (A)

Resistance (Ω)

Fill in values above to see the result

Power (P = VI)

Calculate power from voltage and current.

Voltage (V)

Current (A)

Fill in values above to see the result

Voltage Drop

Single-phase drop across a cable run. The common limit is 3% of supply.

Supply Voltage (V)

Load Current (A)

Cable Length (m)

Conductor Resistance (mΩ/m)

Fill in values above to see the result

Resistors in Series / Parallel

Total resistance of a two- or three-resistor network.

R1 (Ω)

R2 (Ω)

R3 (optional) (Ω)

Connection

Fill in values above to see the result

LED Resistor

Series resistor value to drive an LED safely.

Supply Voltage (V)

LED Forward Voltage (V)

LED Forward Current (mA)

Fill in values above to see the result

Power Factor

Power factor from real (kW) and apparent (kVA) power.

Real Power (kW)

Apparent Power (kVA)

Fill in values above to see the result

Cable Sizing

Minimum copper cross-section limited by voltage drop.

Load Current (A)

Max Allowable Voltage Drop (V)

One-Way Cable Length (m)

Fill in values above to see the result

Voltage Divider

Output voltage from a resistive divider (no load).

Input Voltage (V)

R1 (top) (Ω)

R2 (bottom) (Ω)

Fill in values above to see the result