When to use this calculator
Convert an entered total thermal resistance into a heat-transmittance coefficient. Use total effective resistance for the intended boundary; this does not verify building-standard compliance.
Explore the electricity use & bills calculators for other questions in this topic. For a related calculation, use the Water Heating Cost Calculator: Estimate energy spending for a water-temperature increase under a stated efficiency.
PUTTING IT INTO PRACTICE
U Value From R Value: 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 |
|---|---|
| Total area-normalised resistance (m²·K/W) | 2.5 |
| Result | 0.4 W/m²·K |
- Check the input labels and enter the example values above.
- Apply the relationship: U-value = 1/total R-value.
- The result is 0.4 W/m²·K, rounded for display.
How to interpret your result
Use total effective resistance for the intended boundary; this does not verify building-standard compliance.
Watts describe power and kilowatt-hours describe energy. Fixed charges do not vary directly with consumption. Devices with thermostats or cycling loads need measured average energy or realistic operating time.
Frequently asked questions
Can I multiply rated watts by 24 hours for every appliance?
Only if it actually draws that power continuously. Cycling and variable-power appliances require a better average-use estimate.
When is the u value from r value calculator useful?
Convert an entered total thermal resistance into a heat-transmittance coefficient. Use total effective resistance for the intended boundary; this does not verify building-standard compliance.
How do I use the u value from r value calculator?
Enter total area-normalised resistance (m²·k/w). The result updates automatically. Use the units shown beside each input; the example values illustrate the method.
Which formula does this calculator use?
U-value = 1/total R-value.
What should I check before using the result?
Use total effective resistance for the intended boundary; this does not verify building-standard compliance.
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.
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