Electronic Components
MOSFET Conduction Loss Calculator
This calculator evaluates conduction loss for a single electronic components scenario. It uses drain current and on resistance and shows the equation behind the displayed value.
Calculate Conduction loss
Do not mix values recorded under different conditions.
Preparing the calculation
Keep nominal component markings separate from measured operating values. Write down whether each entry is measured, rated, assumed, or calculated.
Convert units once, retain the original reading, and verify the converted magnitude. A later contact power loss decision can draw on Contact Resistance Loss Calculator.
- Drain current
- Default example: 15 A. Enter drain current in A.
- On resistance
- Default example: 0.018 Ω. Enter on resistance in Ω.
From inputs to result
The arithmetic is based on P = I²RDS(on). Only Drain current and On resistance enter the numerical result.
Using the loaded examples gives 4.05 W. Your saved case should identify where each entry came from.
Calculate conduction loss from drain current and on resistance. Continue to MOSFET Switching Loss Calculator if switching loss is also needed.
Changing Drain current
Change Drain current from 15 A to 18 A without altering the remaining fields. The calculated value shifts from 4.05 W to 5.83 W.
Use a separate scenario when multiple conditions change together.
Interpreting the answer
Interpret Conduction loss on the same basis used for the source values. Compare it with minimum, nominal, and worst-case component values.
Save the raw entries before testing another scenario.
Checks before using the answer
Use on-resistance at the expected junction temperature.
The arithmetic intentionally leaves out parasitics, layout inductance, tolerance stack-up, switching edges, and thermal resistance. Document which effects were checked elsewhere in the analysis.
Keep nominal component markings separate from measured operating values.
Common questions before using the result
Can zero describe the baseline case?
Use zero only when it describes the physical condition. It is not a substitute for missing data.
Which source values should I use for Conduction loss?
Choose entries that describe the same case. Use data-sheet values at the intended voltage, current, frequency, and temperature.
Which assumptions matter most here?
Use on-resistance at the expected junction temperature. A broader review should include parasitics, layout inductance, tolerance stack-up, switching edges, and thermal resistance.
Why might a second instrument give another answer?
Recheck units and operating state before investigating bias dependence, ESR, leakage, saturation, and self-heating.
How do I run a useful sensitivity check?
Keep unaffected entries fixed so the cause of the difference remains visible. Record tolerance, bias point, duty cycle, and junction temperature.
Does the answer include a design margin?
The calculator does not approve equipment or supply an unexplained margin. Compare against minimum, nominal, and worst-case component values.