Radiator output estimator
Compare entered room heat demand with radiator output corrected for your flow, return and room temperatures, rated temperature difference and manufacturer exponent.
Up to 100 uniquely named room rows and 100,000 characters. Demand 0 to 100 million W, rated output above 0 to 100 million W, reference DeltaT exactly 50 or 60 K and exponent 0.5 to 3. Water temperatures -50 to 150°C, room temperature -50 to 100°C; flow must be at least return, and both must exceed room temperature. Calculated on your device. Downloads: JSON report, results CSV and room CSV. One room per line: name, demand W, rated output W, reference DeltaT K, flow °C, return °C, room °C and exponent. Up to 100,000 characters. Review the settings before running.
Your result
How to use Radiator output estimator
- Enter one room per line: name, demand W, rated output W, reference DeltaT K, flow °C, return °C, room °C and exponent.
- Use the radiator rating at 50 or 60 K and its manufacturer exponent; combine only emitters that share those assumptions.
- Choose arithmetic or logarithmic mean temperature difference explicitly.
- Review every room’s surplus or deficit, then download the JSON report and room CSV.
Useful next steps
Temperature difference
Arithmetic mean uses (flow + return) / 2 minus room temperature. Logarithmic mean uses the two positive water-to-room differences and their logarithmic mean. Equal flow and return temperatures use the limiting value. Match the method to the rating you intend to use.
Output correction
Corrected output is rated output × (operating DeltaT / reference DeltaT)^n. At 75/65/20°C the arithmetic difference is 50 K, so a rating at 50 K is unchanged. Exponent 1.3 is an editable example, not a universal radiator property.
Read each room
The signed difference is corrected output minus entered demand. A surplus in one room does not remove a deficit in another. This comparison uses your room demand and product data; it does not calculate building heat loss, pipe capacity or suitable equipment.