Enter the length and width of the room to be heated into the Baseboard Heat Size Calculator (feet are used in the formula below, but you can choose other units in the calculator). The calculator will estimate the required heating output (Baseboard Heat Size) using a rule-of-thumb heat load per square foot.
Baseboard Heat Size Formula
The following example problem outlines the steps and information needed to estimate the Baseboard Heat Size (required heating output) using a simple rule of thumb. Actual baseboard sizing depends on heat loss factors (insulation, air leakage, windows, ceiling height, climate/design temperature, etc.), and baseboard length must be selected based on the heater’s rated output per linear foot.
BHS = L \times W \times 10
Variables:
- BHS is the Baseboard Heat Size (estimated required heating output, in watts (W) or BTU/h)
- L is the length of the room to be heated (ft)
- W is the width of the room to be heated (ft)
- 10 is an assumed heat load of 10 W/ft² (approximately 34 BTU/h per ft²)
To estimate the baseboard heat size, multiply the length by the width to get the floor area in ft², then multiply by 10 W/ft².
How to Calculate Baseboard Heat Size?
The following steps outline how to calculate the Baseboard Heat Size using the rule-of-thumb formula above.
- First, determine the length of the room to be heated (ft).
- Next, determine the width of the room to be heated (ft).
- Next, gather the formula from above = BHS = L * W * 10.
- Finally, calculate the Baseboard Heat Size.
- After inserting the variables and calculating the result, check your answer with the calculator above.
Example Problem :
Use the following variables as an example problem to test your knowledge.
length of the room to be heated (ft) = 10
width of the room to be heated (ft) = 10
BHS = L * W * 10 = 10 * 10 * 10 = 1000 W (≈ 3412 BTU/h)
