Radiator section calculator

Estimate outputs: Required nominal output, Radiators or sections. Adjust Room design heat loss, Output per radiator or section, Output correction factor to match your project.

Inputs and units

Use the units shown beside each field. Replace the sample values with your measurements and the figures on the selected product packaging.

Parameter	Example input
Room design heat loss	3,200 W
Output per radiator or section	160 W
Output correction factor	0.85

Formula and assumptions

Required nominal output
Room design heat loss / Output correction factor / 1000

Radiators or sections
ceil(Room design heat loss / Output correction factor / Output per radiator or section)

ceil = round up; floor = round down; max = the greater value. Trigonometric angles are converted from degrees to radians.

Allowance is applied before rounding to whole packages. Whole units are rounded up; displayed decimals are rounded only for readability.

This is a preliminary geometry or quantity calculation, not a design check. Dimensions, spacing and performance requirements must come from your project.

Heat loss uses one assumed coefficient per floor area. It does not calculate ventilation, individual wall U values or a standards based heating load.

Worked example

Sample values are examples, not product specifications. Run the calculation again with your own measurements.

Result	Calculation
Required nominal output	3.7647 kW
Radiators or sections	24

Related calculators

Related tools use separate measurements. Check their inputs before transferring quantities.