Calculator
Formula Used
Temperatures are converted to Kelvin before ideal comparisons.
- Module input power = V × I × number of modules × duty cycle
- System input power = module input power + auxiliary power
- Useful cold heat = cold side heat × (1 − contact loss ÷ 100)
- Cooling COP = useful cold heat ÷ input power
- Cooling output ratio = cooling COP × 100
- Estimated hot side heat = useful cold heat + module input power
- Heating COP = hot side heat ÷ system input power
- Carnot cooling COP = cold side Kelvin ÷ temperature difference
- Carnot fraction = system cooling COP ÷ Carnot cooling COP × 100
How to Use This Calculator
- Enter the measured hot and cold side temperatures.
- Select the correct temperature units for both surfaces.
- Add module voltage, current, module count, and duty cycle.
- Enter the cold side heat removed from the cooled space.
- Add measured hot side heat when you have reliable data.
- Include fan, pump, or controller power for system COP.
- Use contact loss when interfaces reduce useful heat transfer.
- Press calculate, or export the same data as CSV or PDF.
Example Data Table
| Case | Hot Side | Cold Side | Voltage | Current | Cold Heat | Aux Power | Contact Loss | System COP |
|---|---|---|---|---|---|---|---|---|
| Small cooler | 55 C | 20 C | 12 V | 5 A | 30 W | 3 W | 5% | 0.452 |
| Low lift test | 38 C | 25 C | 9 V | 3.2 A | 22 W | 2 W | 3% | 0.692 |
| High lift test | 70 C | 5 C | 12 V | 6 A | 18 W | 4 W | 8% | 0.218 |
Understanding Peltier Module Efficiency
What the Result Means
A Peltier module is a thermoelectric device. It moves heat when current passes through it. One face becomes cold. The other face becomes hot. Efficiency is usually discussed as COP. COP means coefficient of performance. It compares useful heat pumping with electrical input power.
This calculator estimates cooling COP, heating COP, and a simple output ratio. It also compares the result with a Carnot limit. That limit is an ideal value. Real modules always stay below it. The comparison helps you see how far the setup is from a perfect heat pump.
Input Power and Heat Flow
For cooling work, enter the cold side heat load. This is the useful heat removed from the cooled object. Then enter voltage and current. Their product gives electrical input power. Add fans, pumps, or controller power when you want system level results. A bare module result can ignore those losses.
Temperature difference matters a lot. A small difference allows higher COP. A large difference lowers COP quickly. Poor heat sinking raises the hot side temperature. Bad contact raises the cold side load. Both effects reduce performance. Use measured temperatures when possible.
Losses and Practical Use
The contact loss field is optional. It reduces useful cold side heat after interface losses. This can represent pads, paste gaps, mounting pressure, or insulation errors. It is not a perfect physical model. It is a practical correction for design estimates.
Heating mode is also shown. The hot side heat is often the cold side heat plus electrical input. If you measure hot side heat, enter it. Otherwise the calculator estimates it. Heating COP can be higher than cooling COP because input power becomes heat too.
Use the result as an engineering guide. It can compare module choices, heat sink changes, and operating currents. It cannot replace a full manufacturer test curve. Peltier modules are nonlinear. Their heat pumping changes with current, voltage, and temperature span.
For the best design, keep the hot side cool. Reduce thermal resistance. Insulate the cold chamber. Use the smallest temperature lift that meets the target. Check condensation risks near the cold side. Finally, verify results with measured heat flow and stable temperatures. Record ambient conditions during every test. Room temperature changes heat sink performance. Measured efficiency may drift during long trials.
FAQs
What is Peltier module efficiency?
It is commonly shown as cooling COP. COP compares useful heat removed with electrical power used. A COP of 0.5 means the system removes 0.5 watts of heat for each watt of input power.
Is COP the same as percent efficiency?
Not exactly. COP is a heat pump performance ratio. Multiplying COP by 100 gives an output ratio, but it should not be confused with ordinary energy conversion efficiency.
Why does the calculator need hot and cold temperatures?
The temperature difference controls the ideal Carnot limit. A larger difference makes heat pumping harder. It usually lowers the real Peltier module COP.
What is cold side heat pumped?
It is the heat removed from the cooled load. It can come from a measured heater load, thermal test block, chamber heat gain, or another reliable heat flow estimate.
Should fan power be included?
Include fan, pump, or controller power when you want total system performance. Leave auxiliary power at zero when you only want a bare module estimate.
Why is hot side heat higher than cold side heat?
The hot side must reject the removed cold side heat plus electrical input power. That is why heat sink sizing is critical for stable module operation.
Can the result exceed the Carnot limit?
No real device can exceed the Carnot limit. If the calculator shows that, the heat load, power, or temperature measurements are likely inconsistent.
What improves Peltier performance?
Lower temperature lift, stronger heat sinking, better thermal contact, good insulation, and correct current selection can improve performance. Always verify with measured stable temperatures.