SettingsSettings for this calculationUS
The length of the area you want to heat.
For an open floor plan, measure the full connected area.
Tools needed: Tape measure
The width of the area you want to heat.
Measure perpendicular to the length.
Tools needed: Tape measure
Colder climates need proportionally more heating capacity per square foot.
Consider your typical coldest winter temperatures, not just the average.
Recommended heating capacity (BTU/hr)
23,900 BTU/hr
A rough planning estimate — actual heating needs also depend on insulation quality, ceiling height, and how open the floor plan is to adjacent rooms.
- Space area
- 598 sq ft
- Same output in kW
- 7.01 kW
They open the calculator with your figures already in it
Wood Stove & Fireplace BTU Calculator: 23,920 BTU/hr — 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)
- Rule-of-thumb baseline: approximately 30-60 BTU per square foot for wood stove heating, depending on climate and insulation, with 40 BTU/sq ft as a common moderate-climate starting point
Inputs used
- Space Length
- 26 ft
- Space Width
- 23 ft
- Climate
- Moderate winters
Intermediate steps
- Space area
- 598 sq ft
- Same output in kW
- 7.01 kW
Confidence note: A rough planning estimate — actual heating needs also depend on insulation quality, ceiling height, and how open the floor plan is to adjacent rooms.
What this calculation does not cover
- This sizes from floor area alone. There is no ceiling height or volume input, so a vaulted or cathedral room, a double-height space, or a stove on a lower floor with an open stairwell all read the same as a flat-ceilinged room of the same footprint, and all hold considerably more air to heat than this figure assumes.
- Insulation, air-tightness and glazing are not inputs. The climate selector is the only lever in the model, and it moves the answer across the whole 30-60 BTU per square foot band on its own. An uninsulated house with single glazing and a recently air-sealed one of the same footprint in the same town get an identical number here.
- This is a heat-output estimate, not an installation design. It says nothing about clearances to combustibles, hearth and floor protection, flue and chimney sizing, or combustion and make-up air for a tight house. A solid-fuel appliance install is governed by the manufacturer's listing and by local code and has to be inspected on that basis, not on a BTU figure.
- A manufacturer's published maximum output is not directly comparable to this number. Those ratings come from a laboratory test burn on prepared fuel; sustained output on your own cordwood, at your species and moisture content, is lower. Sizing to a peak rating and then damping the stove down to avoid overheating is what builds creosote in the flue.
- A stove is a single point source, and this assumes the heat reaches everything you measured. Closed doors, corridors and rooms off the stove room will stay cold while the stove room overheats, and no allowance is made for fans, ducting or a heat-distribution kit.
Add the equipment this sizes
This result is a specification — 23,900 BTU/hr — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.
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
- Rule-of-thumb baseline: approximately 30-60 BTU per square foot for wood stove heating, depending on climate and insulation, with 40 BTU/sq ft as a common moderate-climate starting point
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