When to use this calculator
Calculate power dissipated as heat in a resistor. An ideal calculation; component selection needs appropriate thermal margins.
Explore the dc circuits & components calculators for other questions in this topic. For a related calculation, use the RL Time Constant Calculator: Calculate the time constant of an ideal series resistor-inductor circuit.
PUTTING IT INTO PRACTICE
Resistor Power: a worked example
The values below are an illustrative example, not a recommendation. Replace them with measurements or assumptions that match your question.
| Input | Example value |
|---|---|
| Current (A) | 2 |
| Resistance (Ω) | 6 |
| Result | 24 W |
- Check the input labels and enter the example values above.
- Apply the relationship: Power = current² × resistance.
- The result is 24 W, rounded for display.
How to interpret your result
An ideal calculation; component selection needs appropriate thermal margins.
Ideal component models omit tolerances, heat and parasitic effects. Distinguish nominal energy from usable energy for batteries. Component ratings and installation requirements need separate manufacturer and design checks.
Frequently asked questions
Can these calculations select a safe installation rating?
No. They explain ideal relationships and do not include every thermal, protective or regulatory requirement.
How do I use the resistor power calculator?
Enter current (a), resistance (ω). The result updates automatically. Use the units shown beside each input; the example values illustrate the method.
Which formula does this calculator use?
Power = current² × resistance.
What should I check before using the result?
An ideal calculation; component selection needs appropriate thermal margins.
How are results rounded?
Scalar numbers display up to six decimal places, with scientific notation for very large or small values. Text, fraction, date and schedule outputs use the format described on the tool. Intermediate calculations use JavaScript floating-point arithmetic. Keep sensible precision for your measurements.
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