Radiator Heat Output Calculator
Calculate the heat output (kW) of your radiators. Based on Henrad Standard specifications at 75/55°C system temperature.
75/55°C Specifications
Per Radiator Calculation
Total kW Overview
Radiator Types and their Output
Radiator output depends on the type (11, 21, 22, 33), height and length. Type 22 (two panels, two convectors) is the most common in Dutch homes. A Type 22 radiator of 600×1000mm produces approximately 1.5 kW at 75/55°C system temperature. Type 33 delivers the highest output per area, but is also the deepest.
When to Use This Calculator
Use this calculator when sizing radiators for new builds or renovations, verifying whether existing radiators deliver sufficient output, or calculating total heating capacity for expansion vessel sizing. Values are based on Henrad Standard specifications at 75/55°C.
Want to calculate expansion vessel size too?
Expansion Vessel Calculator