When to use this calculator
Find the Carnot thermal-efficiency limit from absolute reservoir temperatures. Ideal upper bound between two reservoirs; actual engines have lower efficiency.
Explore the heat & thermal change calculators for other questions in this topic. For a related calculation, use the First Law Heat Calculator: Apply the first law of thermodynamics with an explicit work-sign convention.
PUTTING IT INTO PRACTICE
Carnot Efficiency: a worked example
The values below are an illustrative example, not a recommendation. Replace them with measurements or assumptions that match your question.
| Input | Example value |
|---|---|
| Hot reservoir temperature (K) | 600 |
| Cold reservoir temperature (K) | 300 |
| Result | 50 % |
- Check the input labels and enter the example values above.
- Apply the relationship: Maximum reversible efficiency (%) = (1 − cold/hot) × 100.
- The result is 50 %, rounded for display.
How to interpret your result
Ideal upper bound between two reservoirs; actual engines have lower efficiency.
Heating within a phase uses specific heat; phase changes use latent heat. Material properties vary with temperature. Ideal conduction calculations omit several real-world heat-transfer paths.
Frequently asked questions
Does heating energy include boiling automatically?
No. Energy to reach a boiling temperature and latent energy to vaporise liquid are separate contributions.
When is the carnot efficiency calculator useful?
Find the Carnot thermal-efficiency limit from absolute reservoir temperatures. Ideal upper bound between two reservoirs; actual engines have lower efficiency.
How do I use the carnot efficiency calculator?
Enter hot reservoir temperature (k), cold reservoir temperature (k). The result updates automatically. Use the units shown beside each input; the example values illustrate the method.
Which formula does this calculator use?
Maximum reversible efficiency (%) = (1 − cold/hot) × 100.
What should I check before using the result?
Ideal upper bound between two reservoirs; actual engines have lower efficiency.
How are results rounded?
Scalar numbers display up to six decimal places, with scientific notation for very large or small values. Text, fraction, date and schedule outputs use the format described on the tool. Intermediate calculations use JavaScript floating-point arithmetic. Keep sensible precision for your measurements.
Further reading
For background on this topic, see OpenStax: thermal expansion ↗. This is a topic reference, not an external review or endorsement of this tool.
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