How to use the resistor power dissipation calculator
Find the power a resistor turns into heat and a safe power rating to choose. Enter resistance, current in the fields above; the power dissipated, recommended rating with 2× margin are computed instantly and plotted on the chart so you can see how the answer changes.
Common searches this calculator answers include “resistor wattage”, “resistor heating”, “what wattage resistor do I need”, “calculate resistor power dissipation”, “find power dissipated”.
Formula
Variables
- R — Resistance (Ω)
- I — Current (A)
Worked example
With resistance = 100 Ω, current = 0.2 A, the calculator gives power dissipated ≈ 4 W; recommended rating with 2× margin ≈ 8 W.
Frequently asked questions
What is the resistor power dissipation calculator used for?
Find the power a resistor turns into heat and a safe power rating to choose. It helps with questions such as “resistor wattage”, “resistor heating”, “what wattage resistor do I need”.
What is the formula for the resistor power dissipation calculation?
Power dissipated (W) = I × I × R. Recommended rating with 2× margin (W) = 2 × [Power dissipated]. Here R is resistance (Ω), I is current (A).
What inputs do I need for the resistor power dissipation calculator?
You need resistance in Ω, current in A. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use the resistor power dissipation calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the resistor power dissipation result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.