Wood Stove Size and Firewood Calculator
Enter the area the stove must heat, your climate and how well the house holds heat. You get the stove output to shop for, how many cords of wood or tons of pellets a winter takes, and what that heat costs next to propane, gas, oil and electricity.
How does the calculator size a stove?
It estimates your home's heat loss, works out the heat needed on a design cold night, and then picks an output band that covers that load without badly oversizing. Each step is shown in the results table above.
- Heat-loss coefficient (UA) = area x (ceiling height / 8) x F, in BTU/hr per degree F. F is 0.25 for a tight house, 0.35 for average and 0.55 for leaky. It lumps walls, windows, roof and air leakage into one number, which is the main simplification here.
- Design heat load = UA x (indoor temperature minus design low) x the stove's share of the heat.
- Stove to shop for: a model whose listed maximum output is at least the design load and no more than 1.5 times it. The firebox band (small under about 2.0 cu ft, medium 2.0 to 2.8, large over 2.8) is a rough guide only, because output depends on the design as well as the box.
Per-square-foot rules of thumb vary widely and ignore your design temperature. University of Maryland Extension's fact sheet "Heating with Wood" (FS-926), for example, quotes 40 to 45 BTU per square foot for a well-insulated home in climate zone 3, while this method gives about 15 for an average house in that zone. A furnace can short-cycle away an oversized rating; a wood stove cannot, which is why this tool starts from heat loss.
How does it work out fuel for a winter?
Seasonal heat (million BTU) = UA x heating degree days x 24 x share / 1,000,000. Degree days at base 65 F already allow for the heat that people, appliances and sun add indoors, so the indoor temperature field changes the design load but not the seasonal total. Fuel needed = seasonal heat / (heat per unit x efficiency). Cost per million BTU delivered = price per unit / (heat per unit x efficiency).
Heat contents: wood from the species table below; pellets at 16.4 million BTU per ton (the value in the EIA heating fuel comparison calculator, editable above); propane 91,452 BTU per gallon, natural gas 100,000 BTU per therm, heating oil 138,500 BTU per gallon and electricity 3,412 BTU per kWh (US EIA conversion values, checked October 2026). Comparison efficiencies: propane and gas furnaces 85%, oil 83%, resistance heat 100%, heat pump at the COP you enter.
How much heat is in a cord of each wood?
Dense hardwoods carry nearly twice the heat of light woods per cord, because a cord is a volume and heat comes from mass. Figures are for a standard cord (128 cu ft stacked, about 80 cu ft of solid wood) air-dried to 20% moisture, at 100% appliance efficiency. Source: University of Maryland Extension, FS-926 "Heating with Wood" (October 2010), Table 1.
| Species | lb per cord, green | lb per cord, air-dried | Million BTU per cord |
|---|---|---|---|
| Osage orange | 5,480 | 4,380 | 30.7 |
| Hickory (shagbark) | 4,980 | 4,160 | 29.1 |
| Locust (black) | 4,640 | 4,010 | 28.1 |
| Oak (white) | 4,942 | 3,863 | 27.0 |
| Oak (red) | 4,988 | 3,609 | 25.3 |
| Maple (sugar) | 4,386 | 3,577 | 25.0 |
| Ash | 3,940 | 3,370 | 23.6 |
| Walnut (black) | 4,640 | 3,120 | 21.8 |
| Hackberry | 4,000 | 3,080 | 21.6 |
| Elm (red) | 4,480 | 3,056 | 21.4 |
| Maple (silver) | 3,783 | 2,970 | 20.8 |
| Sycamore | 4,160 | 2,956 | 20.7 |
| Elm (American) | 4,293 | 2,868 | 20.1 |
| Pine (shortleaf) | 4,120 | 2,713 | 19.0 |
| Red cedar | 3,260 | 2,700 | 18.9 |
| Box elder | 3,500 | 2,500 | 17.5 |
| Cottonwood | 3,920 | 2,304 | 16.1 |
| Basswood | 3,360 | 2,100 | 14.7 |
Published firewood charts disagree with each other by 5 to 15% because they assume different amounts of solid wood per cord. This tool uses one documented source rather than an average of several. Wood above 20% moisture delivers less heat and builds creosote faster; the seasoned firewood guide covers how to check it.
Which climate numbers does each zone use?
Each preset is a representative city for its IECC climate zone. The values are rounded approximations of the 99% heating design temperature and annual heating degree days (base 65 F). Your own weather station can differ a lot from the zone's representative city, especially with elevation, so pick "Custom" and enter local figures when you have them.
| Zone | City | Design low (F) | Degree days (65 F) |
|---|---|---|---|
| Zone 1 | Miami | 47 | 150 |
| Zone 2 | Houston | 33 | 1,400 |
| Zone 3 | Atlanta | 24 | 2,700 |
| Zone 4 | Baltimore | 15 | 4,600 |
| Zone 5 | Chicago | 0 | 6,300 |
| Zone 6 | Minneapolis | -11 | 7,600 |
| Zone 7 | Duluth | -18 | 9,500 |
| Zone 8 | Fairbanks | -40 | 13,500 |
What does this calculator not do?
It does not tell you how to install a stove. Clearances to combustibles, hearth protection, chimney and venting requirements come from the appliance's listing label and installation manual, NFPA 211 and your local building code, and the job should be signed off by your building inspector or a certified installer (NFI or CSIA). Fit working smoke and carbon monoxide alarms. It also does not replace a room-by-room Manual J, and the prices you enter are yours; local firewood and pellet prices can differ by a factor of two.
Where to go next
- Wood stove buying guide: how to read an EPA listing and choose catalytic or non-catalytic.
- Small wood stoves: for loads under about 30,000 BTU/hr.
- What a cord of firewood is: full cord, face cord and rick, and fair prices.
- Seasoned firewood: moisture, drying time and storage.
- Wood pellets: grades, bag counts and what affects heat per ton.
- Pellet stove vs wood stove: running cost, work and power outages.
Frequently asked questions
Quick answers to what readers ask us most
What size wood stove do I need for 2,000 square feet?
It depends on climate and insulation more than on floor area. For 2,000 sq ft with average insulation in a Chicago-like climate (0 F design temperature) at a 68 F setpoint, this calculator estimates a design heat load of about 47,600 BTU/hr, so you would shop for a stove whose EPA-listed output tops out between about 48,000 and 71,000 BTU/hr. The same house in Atlanta needs about 30,800 BTU/hr.
Why not trust the "heats up to 2,000 sq ft" claim on the box?
Square-footage claims assume a climate, insulation level and ceiling height the label does not state, and they usually describe a best case. A heat-loss estimate for your house, compared against the heat output range listed for the model in the EPA Certified Wood Heater Database, is a sounder basis.
Is a bigger wood stove safer than one that is too small?
No. An oversized stove gets turned down to stop the room overheating, and a starved, smoldering fire burns dirty, deposits creosote in the chimney and wastes wood. That is why the calculator caps its recommended band at 1.5 times your design load.
How many cords of wood does a winter take?
Divide the heat your home needs over the season by the usable heat in a cord. Using the example above (2,000 sq ft, average insulation, about 6,300 heating degree days), the house needs about 106 million BTU of delivered heat, and a cord of seasoned red oak burned at 70% efficiency delivers about 17.7 million BTU, so about 6 cords. Softer woods such as cottonwood need far more.
How many tons of pellets will I burn?
At 16.4 million BTU per ton and 75% efficiency, a ton of pellets delivers about 12.3 million BTU. A 1,000 sq ft tight home in a Baltimore-like climate where the pellet stove supplies half the heat needs about 13.8 million BTU, so about 1.1 tons, or 57 bags of 40 lb.
Is this a Manual J load calculation?
No. It is a whole-house estimate built from one heat-loss factor per insulation level. A Manual J done room by room by an HVAC professional uses your actual walls, windows and air leakage. Use this tool to narrow the shopping range, and the appliance manual and a certified installer for the installation.
Can I still claim the federal tax credit for a wood or pellet stove?
Not for a stove placed in service in 2026. The 30% federal credit for biomass stoves of at least 75% efficiency (Section 25C, up to $2,000 a year) ended for property placed in service after December 31, 2025, under the law signed on July 4, 2025. Check your state energy office for any state or utility rebates.