Heat loss estimate calculator

Estimate outputs: Design heat loss. Adjust Heated floor area, Specific heat-loss coefficient, Indoor to outdoor temperature difference 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
Heated floor area	100 m²
Specific heat-loss coefficient	0.9 W/m²K
Indoor to outdoor temperature difference	32 K
Design allowance	10 %

Formula and assumptions

Design heat loss
Heated floor area × Specific heat-loss coefficient × Indoor to outdoor temperature difference × (1 + Design allowance / 100) / 1000

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
Design heat loss	3.168 kW

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