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Tooliyapa

Electrical calculator

Electrical Calculator

Use two known electrical values to derive voltage, current, resistance, and power with Ohm’s Law and ideal resistive power relationships.

Choose any supported pair. The calculator derives voltage, current, resistance, and power.

Enter volts. Use a positive base-unit value.

Enter amperes. Use a positive base-unit value.

This calculator applies ideal DC / purely resistive relationships. It does not account for AC power factor, phase angle, reactance, impedance, startup current, wiring limits, or electrical safety requirements.

Electrical result

Enter two known values to calculate

Ohm’s Law

Ohm’s Law relates voltage, current, and resistance: V = I × R. Rearranging the same relationship gives I = V ÷ R and R = V ÷ I. If any two of these quantities are known for an ideal resistive circuit, the third can be calculated.

Electrical power

For ideal DC or purely resistive conditions, electrical power is P = V × I. Combining this with Ohm’s Law also gives P = I²R and P = V² ÷ R. Those equivalent forms allow the calculator to solve all four quantities from several different known-value pairs.

What the calculator can solve

Choose voltage and current, voltage and resistance, voltage and power, current and resistance, current and power, or resistance and power. The calculator derives the remaining quantities and shows the formula path used.

Units

Enter base SI units: volts (V), amperes (A), ohms (Ω), and watts (W). For example, convert 250 mA to 0.25 A and 4.7 kΩ to 4700 Ω before entering the values. The outputs are also shown in these base units.

AC circuits and power factor

Real AC circuits can include reactance, impedance, phase angle, apparent power, reactive power, and power factor. This calculator does not model those effects, so the simple P = V × I relationship should not be treated as a complete AC power calculation unless the circuit is appropriately resistive and the assumptions apply.

Safety and design limitations

This page is a formula calculator, not an electrical design or safety tool. It does not size conductors, breakers, fuses, insulation, enclosures, grounding, thermal limits, or protective devices. Follow applicable electrical codes, manufacturer data, and qualified professional guidance for real installations.

Frequently asked questions

Why must the inputs be greater than zero?

Several inverse formulas divide by a known quantity. Restricting inputs to positive values avoids zero-division and degenerate cases where the remaining values are not uniquely determined.

Can I enter milliamps or kilohms directly?

Convert them first: divide milliamps by 1000 to get amperes, and multiply kilohms by 1000 to get ohms.

Does this work for three-phase power?

No. Three-phase systems require different formulas and often power-factor information, so they are outside this calculator’s scope.