Maximum Resistor Power Calculator

The below calculator is designed to calculate the maximum power that a resistor can dissipate based on a given heat sink size and ambient conditions. This calculator assumes 1°C/W for the thermal resistance of the resistor body to the heat sink case.

Enter values below and the result will automatically be calculated.

Thermal resistance of external heat sink:   °C/W
Maximum resistance temp:   °C
Maximum ambient temp:   °C
Thermal resistance element to case:   °C/W
Power dissipated in resistor:   Watts

Popular manufacturers

The table below offers a selection of our power resistors and their specifications, all of which are heat sink mountable:

SeriesThermal ResistaceResistance RangeToleranceTCRPower RatingPackaging
Caddock MP9158.33°C/W0.02Ω to 1kΩ±1.0% (from 0.05Ω)-20 to +80 ppm/°C (from 0.5Ω)15WTO-126 style
Caddock MP9167.81°C/W0.01Ω to 0.019Ω±5.0%0 to +500 ppm/°C16WTO-126 style
Caddock MP9255.00°C/W5kΩ to 100kΩ±1.0%-20 to +80 ppm/°C25WTO-220 style
Caddock MP9304.17°C/W0.02Ω to 4.99kΩ±1.0% (from 0.05Ω)-20 to +80 ppm/°C (from 0.5Ω)30WTO-220 style
Caddock MP91001.50°C/W0.05Ω to 100Ω±1.0%-20 to +80 ppm/°C (from 0.5Ω)100WTO-247 style
Isabellenhütte PBH4°C/W0.002Ω to 100Ω±0.5% (from 0.01Ω)<50 ppm/°C10WTO-247 style
Isabellenhütte PBV3°C/W0.0005Ω to 1Ω±0.5% (from 0.0015Ω)<30 ppm/°C (from 0.01Ω)10WNon-standard
Isabellenhütte A-H23°C/W0.001Ω to 100Ω±0.1% (from 0.001Ω)<30 ppm/°C10WNon-standard

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