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Wood Stove BTU Output

Heating with wood is a numbers game. A pound of oak releases about 7,000 BTU when fully burned; a pound of pine, only 4,500. A typical wood stove burns 5-10 lb of wood per hour depending on size and damper setting. Multiply those together and you get the actual heat output going into your house — typically 25,000-70,000 BTU/hr, comparable to a small furnace. This calculator takes your wood species, burn rate, and daily burn hours and returns BTU/hr, cords needed for a typical 5-month winter, and daily wood consumption. Plan your woodshed accordingly.

BTU/hr

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Cords / 5-month winter
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Daily wood (lb)
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BTU/cord
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BTU content by wood species

BTU per cord (seasoned at 20% moisture content):

  • Hickory, white oak: ~28-30 million BTU/cord. Densest, longest-burning.
  • Red oak, sugar maple, beech: ~24-27M BTU/cord. Excellent firewood, easy to source.
  • Ash, walnut, cherry, birch: ~20-23M BTU/cord. Good firewood, splits cleanly.
  • Soft maple, elm: ~18-20M BTU/cord. Decent but less dense.
  • Pine, spruce, fir: ~14-17M BTU/cord. Softwoods burn fast, more creosote.
  • Aspen, cottonwood, basswood: ~12-14M BTU/cord. Lowest density, kindling territory.

A cord is 128 cubic feet of stacked wood (4 ft × 4 ft × 8 ft). Different species have different weights per cord because they have different densities — a cord of oak weighs ~3,700 lb dry, a cord of pine weighs ~2,400 lb dry.

Burn rate and stove sizing

Modern EPA-certified wood stoves range from small (1.5 cu ft firebox) to large (3+ cu ft). Practical burn rates:

  • Small stove (1.5 cu ft): 3-5 lb/hr, ~20,000-35,000 BTU/hr
  • Medium stove (2-2.5 cu ft): 5-8 lb/hr, ~35,000-56,000 BTU/hr
  • Large stove (3+ cu ft): 8-12 lb/hr, ~56,000-84,000 BTU/hr

Worked example: medium stove burning red oak at 6 lb/hr for 12 hr/day, 5-month winter (150 days). Hourly output = 6 lb × 6,500 BTU/lb = 39,000 BTU/hr. Daily wood = 72 lb. Total wood = 72 × 150 = 10,800 lb = ~3 cords of oak (oak at ~3,700 lb/cord). Plan to lay in 3.5 cords with margin.

How to use this calculator

  1. Wood species: pick the one closest to what you're burning.
  2. Burn rate in lb/hr (typically 3-10 lb).
  3. Hours per day: how long the stove typically runs (often 12-16 hr/day in winter).
  4. Output: BTU/hr, cords per 5-month winter, daily wood consumption, BTU per cord.
  5. Plan winter wood: order 1 cord more than calculated to handle cold snaps and shoulder season.

Common scenarios

Vermont farmhouse with medium oak stove, 14 hr/day, 5-month winter. Oak at 6 lb/hr = 39,000 BTU/hr. 84 lb/day = 12,600 lb = ~3.4 cords. Plan 4 cords. At $250-350/cord delivered, that's $1,000-1,400 for winter heating.

Cabin with small pine stove, 8 hr/day, weekends only (4 months total of weekends). Pine at 4 lb/hr = 18,000 BTU/hr. 32 lb/day. ~30 weekend days. 960 lb of pine = about 0.4 cord. One cord is plenty with leftover for next year.

Northern Wisconsin year-round wood-heated house, large stove, mixed hardwoods, 16 hr/day, 6-month winter. Maple at 9 lb/hr = 58,500 BTU/hr. 144 lb/day × 180 days = 25,920 lb. At 22M BTU/cord = ~8.2 cords. Plan 10 cords for safety. Need a major woodshed (at least 1,280 cu ft of stack space).

FAQ

Does seasoning really matter? +
Hugely. Green (fresh-cut) wood is 40-60% water by weight, and the stove has to boil that off before generating useful heat. Effective BTU output is cut by 40-60% with green wood, AND green wood produces 5-10x more creosote (chimney fire risk). Season hardwoods 1-2 years; softwoods 6-12 months. Target 15-20% moisture for clean efficient burns. A $25 moisture meter is the right tool.
How big is a cord, exactly? +
128 cubic feet of stacked wood (4 ft x 4 ft x 8 ft). "Face cord" or "rick" is 1/3 of a full cord (4 ft x 8 ft x 16" deep — the typical 16" stove log length). When buying wood, always confirm "full cord" vs "face cord" — the price difference is 3x for the same word "cord" used differently.
How do I know what kind of wood I have? +
Bark, wood color, weight, splitting behavior. Oak: gray ridged bark, light yellow wood, splits clean. Maple: smooth gray bark, light yellow-white wood, splits easy. Pine: scaly red bark, very light tan wood, sticky pitch. There are several free tree-ID phone apps (PlantNet, Picture This) that work from a photo of a leaf or piece of bark.
Hardwood vs softwood — actual difference? +
Hardwoods (oak, maple, hickory) are dense, burn slow, produce long-lasting coals, ideal for overnight burns. Softwoods (pine, spruce, fir) are less dense, burn fast and hot, produce less long-lasting heat. Softwoods make great kindling and shoulder-season fires; hardwoods are the winter workhorses. Mixed wood stack: 1/3 softwood + 2/3 hardwood is the practical default.
How often do I clean the chimney? +
Once per cord burned, or annually — whichever comes first. Modern EPA stoves on well-seasoned hardwood may go 1.5-2 cords between cleanings. Wet wood or smoldery fires accelerate creosote and may require mid-winter cleanings. A chimney brush + 25-ft fiberglass rod is a $100-150 home-owner kit; professional sweep $150-300.
What about pellet stoves? +
Pellets are processed sawdust at 8,000-8,500 BTU/lb, packed in 40-lb bags. Pellet stoves are easier than wood (auger feeds the firebox automatically, electronic thermostat), but pellets cost $5-7/bag = $200-300/ton, and 1 ton of pellets ~= 1.5 cords of seasoned wood by heat output. Pellets are more convenient; wood is cheaper if you can source/process it yourself.
Can wood heat replace my furnace? +
For a well-insulated house in a moderate-winter climate (most of New England, upper Midwest): yes, if you commit to the daily fire-tending routine. Backup heat (oil, propane, electric) for sub-zero spells and times away from home is the smart setup. Many wood-heated houses also have a propane backup that kicks in if the indoor temp drops below 60°F.
What's a reasonable wood-heat cost vs. propane? +
Self-cut/processed wood: $0-50/cord just for chainsaw fuel and your time. Delivered seasoned wood: $250-400/cord. 1 cord of hardwood = ~20M BTU = roughly 220 gallons of propane equivalent ($600-700 at typical propane prices). Self-processed wood is the cheapest residential heat by a wide margin; even delivered wood beats propane by 40-60%.