Circuit Calculator

Calculate common circuit values including voltage, current, resistance, power, series resistance, parallel resistance, circuit load, watts, amps, and basic Ohm's Law results.

Calculate Circuit Values

Circuit formulas: V = I × R, I = V ÷ R, P = V × I, Series R = R1 + R2 + R3, Parallel R = 1 ÷ (1/R1 + 1/R2 + 1/R3).
Your result will appear here.

How the circuit calculator works

Ohm's Law circuit:
Use voltage, current, resistance, and power formulas to solve a missing circuit value.

Series resistance:
Add each resistor value together to estimate total circuit resistance.

Parallel resistance:
Add the reciprocal of each resistance value, then take the reciprocal of that total.

Why use a circuit calculator?

A circuit calculator helps estimate common electrical values when designing, checking, or troubleshooting simple circuits.

It can help with Ohm's Law, resistor combinations, circuit current, watts, amps, breaker load estimates, electronics projects, DC circuits, and basic electrical planning.

What your result means

Your result shows solved circuit value, voltage, current, resistance, power, series resistance, parallel resistance, load percentage, energy estimate, component totals, and a calculation summary.

Circuit calculator formulas

Frequently asked questions

What does a circuit calculator do?

A circuit calculator estimates common circuit values such as voltage, current, resistance, power, series resistance, and parallel resistance.

How do I calculate current in a circuit?

Use I = V ÷ R. Divide voltage by resistance to estimate current in amps.

How do I calculate total resistance in series?

Add each resistor value together. For example, 10 ohms plus 20 ohms plus 30 ohms equals 60 ohms.

How do I calculate total resistance in parallel?

Use the reciprocal formula: total resistance equals 1 divided by the sum of each reciprocal resistance.