SettingsSettings for this calculationUS
The floor area of the room to heat.
Measure the room's length x width.
Recommended heater size
2,200 W
This is a general rule of thumb for average-insulated rooms with standard 8 ft (2.5 m) ceilings. Poorly insulated rooms, high ceilings, large uncovered windows, or very cold climates need more capacity — a full room-by-room heat loss calculation gives a more precise number.
- Equivalent heat output
- 7,506.71 BTU/hr
They open the calculator with your figures already in it
Electric Baseboard Heater Sizing Calculator: 2,200 W — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
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How this was calculated
Formula source(s)
- Common electric baseboard heating rule of thumb: 10 watts per square foot for an average-insulated room with 8 ft ceilings
Inputs used
- Room Area
- 220 sq ft
Intermediate steps
- Equivalent heat output
- 7,506.71 BTU/hr
Confidence note: This is a general rule of thumb for average-insulated rooms with standard 8 ft (2.5 m) ceilings. Poorly insulated rooms, high ceilings, large uncovered windows, or very cold climates need more capacity — a full room-by-room heat loss calculation gives a more precise number.
What this calculation does not cover
- The 10 watts per square foot figure is a flat rule of thumb, not a heat loss calculation. Insulation level, air tightness, window area and orientation, how many walls face outside, and the local design temperature are not inputs, so a corner room with large glazing in a cold climate and an interior room in a well-insulated house of the same floor area return the same number.
- Floor area is the only input, so the assumed standard ceiling height is baked in. Vaulted or double-height rooms, and rooms sitting over an unheated crawl space, garage or open porch, are not accounted for.
- This is a heat output figure, not an electrical calculation. It does not size a branch circuit, check conductor ampacity or breaker rating, distinguish 120 V from 240 V units, or consider how many heaters share a circuit. Electric space heating is a continuous load and the circuit has to be designed and permitted separately.
- The answer is a continuous wattage, not a product. Baseboard heaters are sold in fixed wattages at a fixed watts-per-foot density, so the required output translates into a specific physical length that has to fit on clear wall — usually under a window, away from furniture, curtains and receptacles.
- Use a room-by-room heat loss calculation anywhere a design figure has to stand up: whole-house sizing, permit or rebate submissions, or high-performance builds, where this rule of thumb consistently oversizes because it was calibrated on ordinary older construction.
Add the equipment this sizes
This result is a specification — 2,200 W — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.
Part of a bigger job
Or plan the space itself: measure it once, doors and windows included, and this figure comes back worked out on that space, with what goes with it.
Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.
Sources checked 2026-09-02 · in the site-wide review of 2026-09-06 · v1.0.1
Regulatory standards & verification citations1
- Common electric baseboard heating rule of thumb: 10 watts per square foot for an average-insulated room with 8 ft ceilings
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