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

Users are hereby informed that Rhopoint accepts no responsibility for any inaccuracies or issues that may arise from the use of our online calculators. All data and results should be independently verified prior to their application in any projects or calculations.

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