Connector Current Derating Calculator (Temperature Derating Curve)
Derate a connector’s rated current for ambient temperature — the curve on the datasheet — with a table and chart.
Inputs
I(Ta) = I_rated × √((T_max − Ta) / (T_max − T_ref)) for Ta above the reference; at or below the reference no uprating is applied. This is the standard I²R heating model behind datasheet derating curves; where the datasheet gives a curve, the datasheet wins.
Derating table
Frequently asked questions
Why does a connector’s current rating fall at high temperature?
Current heats the contacts (I²R) on top of the ambient temperature, and the plastic and plating have a maximum operating temperature. As the ambient rises, less temperature rise is allowed, so the permitted current falls. Always use the derating curve in the manufacturer’s datasheet for the actual part.
For preliminary assessment only — the final decision must follow the manufacturer’s datasheet and the applicable NEC / IEC / UL standards. Results are calculated from the standard formulas stated on this page and are for design estimates only. They are not a rating of any specific part — always confirm current, voltage, temperature and environment limits against the manufacturer’s datasheet for the part you intend to use.
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