Enter the area you want to heat, your winter climate and how well the house holds heat. You get a rough heat-need range in Btu per hour to compare with the overall heat output range on a stove’s spec sheet. It runs in your browser; nothing is stored.

Wood stove sizing calculator

1. The space you want to heat

Area to heat (sq ft)

Only the connected, open area the stove can reach. Closed-off rooms heat poorly from one stove.

Your winter climate

Example design temperatures. Your local code office or an HVAC contractor can give the 99% heating design temperature for your county.

Winter design temperature (°F)

Filled from your climate choice; type over it with your county value.

Insulation and air sealing

Planning factor in Btu/h per sq ft per °F (our assumption, see below).

Your estimated heat need on a design-cold day

Central estimate (Btu/h)

Range, from (Btu/h)

to (Btu/h)

That is more than most single residential wood stoves are rated to sustain. Get a professional heat-loss calculation, improve insulation first, or plan a second heat source.

A small heat need. A small-firebox stove usually fits; a large stove would often be run turned down, which the EPA advises against (smoldering fires).

Compare with stove specs

Look at the overall heat output range (certification test data) and EPA loading volume, not the maker's heating-area claim. Examples from our articles: Drolet Escape 1500 / Osburn 1700, 9,800-52,200 Btu/h, 1.44 ft³ loading volume; Drolet Escape 1800, 14,200-44,500 Btu/h, 1.95 ft³. Your central estimate should sit inside a stove's range, ideally not at the very top.

How this is calculated

Heat need (Btu/h) = area × planning factor × (70°F indoors − winter design temperature), shown ±20% and rounded to 100. The planning factors (0.25, 0.35, 0.5 Btu/h per sq ft per °F) and the example climate temperatures are our rough assumptions for a first look, not a published standard. A room-by-room heat-loss calculation (ACCA Manual J) by a heating professional is the reliable method. Stove figures: Drolet and Osburn spec pages, checked Oct 12, 2026.

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How the math works

Heat need (Btu/h) = area × planning factor × (70°F − winter design temperature), shown as a range of ±20% and rounded to 100.
Planning factors (0.25 tight, 0.35 average, 0.5 drafty, in Btu/h per sq ft per °F) and the example climate temperatures are our own rough assumptions for a first look. They are not from a published standard.
A room-by-room heat-loss calculation (ACCA Manual J) by a heating professional is the reliable method. Your local code office can tell you the heating design temperature for your county.

Compare the result with a stove’s overall heat output range and EPA loading volume, not its heating-area claim. Drolet, for example, defines heated area as the stove’s “capacity to maintain a minimum acceptable temperature in the designated area in case of a power failure.” See what size wood stove do I need for a walk-through.