Floor Heating Heat Loss Calculator

WarmlyYours floor heating systems can be an effective primary heat source. However this effectiveness can vary given such variables as climate, insulation and position of the room that you want to heat in your home. This innovative online tool can help you determine if the room you would like to heat is a good candidate.

Click the button below to find out whether our floor heating systems can be used as the primary source of heat in your room, create a new project/room and select the Heat Loss Calculation option after you see your instant quote options.

Heat Loss Calculator

Special Note:

When setting the temperature of your floor heating system, ensure compliance with the floor covering manufacturer's required maximum temperature limit, if applicable to your floor covering type. Due to some flooring manufacturer's maximum temperature limitations, some floor covering types may not serve as an optimal choice for a primary/sole heating source.

Please note that to use the Heat Loss Calculator you’ll be asked to create a WarmlyYours account—this will help us provide greater specificity in your Heat Loss Calculation and it will also be easier to make changes to future projects we work on together.

Frequently Asked Questions

Showing all 6 questions

How do I calculate heat loss in a room?

Measure each surface that touches the outdoors — walls, windows, doors, ceiling, and floor — divide each area by its R-value, then multiply by the difference between your desired indoor temperature and your design outdoor temperature. Add the results for the room’s total BTU/hr loss. Our free Heat Loss Calculator handles the math for you.

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How many BTUs does electric floor heating produce per square foot?

A 15-watt-per-square-foot system such as TempZone™ delivers roughly 51 BTU/hr for every square foot of heated floor, since one watt equals about 3.412 BTU/hr. So 100 square feet of heated area produces about 5,100 BTU/hr. Because heating elements can’t run under cabinets or fixtures, plan on covering at least 80% of the floor when you compare output to your room’s heat loss.

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Is basement heat loss different from an above-grade room?

Yes. Below-grade walls and slabs lose heat to soil that stays far warmer than winter air, so a basement often has lower heat loss than a comparable room upstairs — which makes radiant floor heating a strong candidate for primary heat. Insulate under the slab and at the rim joists, and account for egress windows and any walk-out walls in your calculation.

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What if my room's heat loss is higher than my floor heating output?

Then the floor alone won’t hold your target temperature on the coldest days. You have two options: reduce the heat loss — add insulation, upgrade glazing, seal air leaks — and re-run the calculation, or use radiant floor heating as supplemental comfort heat alongside your existing system. Either way, our engineers can review your numbers and recommend a system at no cost.

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What information do I need to use the Heat Loss Calculator?

Have these details ready before you start:

Room length, width, and ceiling height
Wall, ceiling, and floor construction or insulation R-values
Window and door sizes plus glazing type (single, double, or triple pane)
Your city or design outdoor temperature
The indoor temperature you want to maintain

Estimates are fine — you can adjust inputs and re-run the calculation as often as you like.

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What is a heat loss calculation for radiant floor heating?

A heat loss calculation measures how many BTUs per hour a room loses through its walls, windows, doors, ceiling, and floor on the coldest day of the year. Compare that number to your radiant system’s heat output: if the floor produces more BTUs than the room loses, it can heat the space on its own.

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