Ohm's Law Power Calculator
Calculate electrical power using Ohm's Law P = V × I = I²R = V²/R. Enter any two values of voltage, current, or resistance to find power in watts with charts.
About This Calculator
The Ohm's Law Power Calculator helps you compute electrical power in watts using the fundamental relationship between voltage, current, and resistance. Enter any two known values, and the calculator instantly determines the electrical power and the missing parameter using P = V × I, P = I²R, or P = V²/R.
This free online tool is ideal for electronics students, electrical engineers, hobbyists, and professionals who need quick power calculations for DC and resistive AC circuits. The results include the computed power, voltage, current, and resistance with interactive charts and a detailed breakdown table.
How It Works
Ohm's Law states that voltage equals current times resistance (V = I × R). Electrical power is the product of voltage and current (P = V × I). By combining these, power can also be expressed as P = I²R or P = V²/R. This calculator gives you all four values when you supply any two.
About This Calculator
The calculator uses standard SI units (volts, amperes, ohms, watts) that are universally used in physics and engineering. Simply enter your known values, click calculate, and get instant results with visual charts. The URL saves your inputs for easy sharing or bookmarking.
Frequently Asked Questions
What is Ohm's Law and how is power related?
Ohm's Law states that voltage V = I × R, where I is current in amperes and R is resistance in ohms. Electrical power P = V × I = I²R = V²/R. This calculator computes power from any two known values of voltage, current, or resistance.
How do I use this Ohm's Law power calculator?
Enter any two of the three values: voltage (V) in volts, current (I) in amperes, or resistance (R) in ohms. Click calculate to get the electrical power in watts along with the computed third value. For example, enter 12 V and 2 A to get 24 W of power and 6 Ω of resistance.
What is the formula for electrical power from Ohm's Law?
The electrical power formula derived from Ohm's Law has three forms: P = V × I (using voltage and current), P = I² × R (using current and resistance), and P = V² / R (using voltage and resistance). All three give the same result in watts for resistive circuits.
What units does this calculator use?
This calculator uses standard SI units: voltage in volts (V), current in amperes (A), resistance in ohms (Ω), and power in watts (W). All physics and engineering formulas work in these units regardless of country.
Can I calculate power if I only know voltage and resistance?
Yes. Enter voltage and resistance, and the calculator will compute current using I = V/R and then power using P = V × I, or directly P = V²/R. This works for any two known values.
Is this calculator free to use?
Yes, this Ohm's Law power calculator is completely free to use with no registration, hidden charges, or usage limits. You can bookmark or share your calculations via the URL.