Free Firewood BTU Calculator - Heat Content by Species
Calculate the heat content (BTU) of a firewood stack by species and volume. Plan your winter heating with accurate energy estimates.
Choose a species and enter the volume in cords to estimate heat content.
A cord of firewood is not one fixed amount of heat. Two stacks can look identical from the driveway and behave very differently in the stove because species, moisture, stack volume, and appliance efficiency all change the usable heat you get from the wood. The Firewood BTU Calculator gives you a practical estimate by multiplying the volume you have by a species-specific heat value, then expressing the result in millions of BTU.
Use the number as a planning estimate, not as a laboratory result. It is strong enough to compare oak against pine, half a cord against two cords, or one supplier quote against another. It is not precise enough to promise how many nights a stack will heat a specific house, because a home loses heat through insulation, air leakage, climate, stove operation, chimney draft, and daily weather.
The calculator estimates the gross heat content stored in a firewood stack. If you enter 1.5 cords of a species rated at 24 million BTU per cord, the tool returns about 36 million BTU before appliance losses. That is the energy available in the wood under the assumptions behind the rating, not the exact heat that will end up in your living room.
The key input is the cord. A standard full cord is an evenly stacked pile that contains 128 cubic feet of wood and air space, often pictured as a 4-foot by 8-foot by 4-foot stack, according to Utah State University Extension’s wood-heating guidance on cord volume. If your seller uses a face cord, rick, truckload, rack, or loose pile, convert it before trusting any BTU result.
The basic method is simple:
Total heat content = number of cords x BTU per cord for the selected species
If you have 2 cords of red oak and you use a 24 million BTU-per-cord value, the estimated heat content is 48 million BTU. If you have the same 2 cords of a lower-density softwood at 16 million BTU per cord, the estimate drops to 32 million BTU. The stack size did not change, but the density and species did.
The calculator rounds the result to the nearest 0.1 million BTU because firewood is not measured with laboratory precision at home. Split size, bark percentage, actual moisture, stacking tightness, and regional growing conditions all create variation. A tidy decimal is useful for comparison, but the real-world answer should be treated as a range.
This is also why the calculator works best when you run more than one scenario. Enter the supplier’s stated species first, then run a lower-value species if the load is mixed or uncertain. Enter the measured cord volume, then run the number again after subtracting any obvious air gaps, short rows, or loose tossing. If the answer changes enough to affect a purchase, the measurement issue matters more than the decimal.
Firewood is usually bought by volume, but heat follows dry weight and density more closely than pile size. The USDA Forest Products Laboratory explains that hardwoods are roughly 8,600 BTU per dry pound and softwoods about 9,000 BTU per dry pound, but most hardwoods produce more heat per cord because they are denser and pack more dry wood into the same volume per dry pound.
That is why a cord of dense hardwood can last longer than a cord of light softwood even when the softwood has a respectable heat value per pound. Utah State University Extension lists osage-orange, oaks, locust, maple, ash, and other dense woods high in dry heat per cord, while lighter woods such as basswood, cottonwood, spruce, and white pine sit much lower on the same species table. The calculator uses that same practical idea: compare the stack by species first, then adjust expectations for moisture and stove performance.
BTU per cord is most useful when you compare two realistic options. A supplier offering cheaper softwood may still be a good deal if the price per million BTU is lower, the wood is dry, and you need easier heat control for mild weather. A more expensive hardwood may be the better buy for deep winter if it gives more heat per delivery, fewer reloads, and longer coaling.
Do not treat a species value as a personality test for wood. Pine is not “bad” because it has fewer BTU per cord than oak. It is lighter, often easier to split, and can be useful for kindling, shoulder-season fires, or quick heat. Dense hardwoods are not automatically better for every burn either; they can be slow to season, harder to ignite, and too much heat for a mild evening.
Mixed loads need a practical compromise. If the stack is half oak and half maple, average the two estimates by volume. If the pile is a true mix and you cannot sort it, choose a conservative middle value instead of the highest species you see. The calculator is meant to prevent overconfidence, so a cautious mixed-load estimate is usually more useful than a best-case number that assumes every split is premium hardwood.
The calculator expects cords because a cord has a defined volume. Illinois Extension describes a full cord as a tightly stacked 4-foot by 4-foot by 8-foot pile and notes that face cords can vary because the missing third dimension depends on log length when comparing prices. A face cord of 16-inch pieces is often about one-third of a full cord, but a face cord of 12-inch pieces is smaller.
Truckloads are even less reliable. Bed size, sideboards, loose tossing, split length, and stacking tightness all matter. If you want the calculator to give a useful answer, stack the wood first, measure length, height, and depth in feet, multiply those dimensions, then divide by 128 to estimate cords.
For example, a stack that measures 8 feet long, 4 feet high, and 16 inches deep is about 42.7 cubic feet, because 16 inches is 1.33 feet. Dividing 42.7 by 128 gives about 0.33 cord. If a seller calls that a full cord, the BTU estimate will be three times too high. If they call it a face cord, the number may be fair, but only after you know the depth.
The species number assumes dry or seasoned wood. Green wood contains water, and some combustion energy is spent boiling that water instead of heating the room. Utah State University Extension notes that green firewood may contain 50 percent or more water by weight, produces less heat, and can create more smoke and creosote than dry wood before drying.
EPA’s Burn Wise guidance is the practical rule to use at home: wood burns best at less than 20 percent moisture content, and a moisture meter should be used before burning less than 20 percent. Measure on a freshly split face, not only on the weathered outside of a log. The outside can read dry while the interior still holds enough moisture to steal heat, smoke, and make the stove harder to control.
Seasoned wood has been split, stacked, and air-dried long enough to burn cleanly. EPA recommends seasoning wood for at least six months and storing it outdoors, off the ground, with only the top covered so the sides can keep drying seasoning guidance. EPA’s appliance-efficiency page adds a useful rule of thumb: softwood may need at least 6 months, while hardwood may need at least 12 months properly dried wood.
Kiln-dried firewood can be excellent when it is honestly dried and handled well, but the label alone does not replace measurement. It may also cost much more per million BTU than bulk local seasoned wood. Green wood can be worth buying ahead if the price is right and you have storage time, but it should be treated as future fuel, not as reliable heat for the current cold snap.
The calculator estimates heat in the wood. Your stove, insert, furnace, or fireplace decides how much of that heat reaches the house. EPA distinguishes combustion efficiency from overall efficiency, with overall efficiency being the better measure of heat transferred to the space being heated overall efficiency.
That distinction matters when comparing firewood to heating oil, natural gas, propane, or electric heat. If the calculator says a stack contains 60 million BTU and your appliance delivers 70 percent overall efficiency under real operation, the useful heat is closer to 42 million BTU. An open fireplace may feel warm nearby while pulling heated air up the chimney, so the same wood can heat very differently depending on the appliance.
Suppose you can buy 1 cord of oak or 1.5 cords of pine. If the oak value is about 24 million BTU per cord, the oak stack contains roughly 24 million BTU. If the pine value is about 16 million BTU per cord, the 1.5-cord pine stack also contains roughly 24 million BTU.
That does not make the two offers identical. The pine will likely occupy more storage space for the same estimated heat, may require more frequent loading, and may burn faster. The oak may cost more, dry more slowly, and be harder to split. The calculator gives you the energy comparison; your storage, stove, labor, and price decide which option actually fits.
Imagine you used 3 cords of mixed hardwood last winter and your house felt comfortable. This year a supplier offers 2 cords of hickory and 1 cord of soft maple. If hickory is entered near 28 million BTU per cord and soft maple near 19 to 22 million BTU per cord depending on the table value used, the stack may land around 75 to 78 million BTU before appliance losses.
That estimate is useful because it lets you compare the new order with last year’s actual experience. If last year’s mix was mostly red oak and maple, the new stack may be similar or slightly stronger. If last year’s winter was unusually mild, your same BTU total may not be enough in a colder year. The calculator improves the comparison, but your previous burn rate is still one of the best local data points you have.
The most practical buying comparison is price per million BTU, not price per cord. Divide the delivered price by the calculator’s estimated million BTU. A $360 cord rated at 24 million BTU costs $15 per million BTU before stove losses. A $240 cord rated at 16 million BTU also costs $15 per million BTU before stove losses.
Now add the non-energy costs. Wet wood has a hidden cost because you pay to haul water and then spend heat evaporating it. Short loads have an obvious cost because the seller delivered less volume than you priced. Poorly split wood can add labor, drying time, and storage frustration. A bargain becomes less attractive when the calculator, tape measure, and moisture meter all disagree with the sales pitch.
Delivery distance also matters. A slightly higher local price may still be better if it avoids long hauling, reduces invasive-pest risk, and gives you a supplier who can explain the wood’s source and drying history. The calculator cannot price trust, but it can show whether an apparently cheap load is only cheap because it contains fewer usable BTU than the alternative.
A BTU estimate is only as good as the wood you preserve after delivery. Stack the wood where air can move, keep it off wet ground, and cover the top without wrapping the sides. EPA specifically warns that covering the sides traps moisture, which is the opposite of what you want when you are trying to season fuel store wood outdoors.
Single rows dry faster than tight blocks because more cut ends and split faces see moving air. Sun helps, but airflow is usually the bigger win. If you stack several rows together, leave space between them. If you use pallets, rails, or a simple woodshed, make sure the base stays stable as the pile shrinks and shifts through the season.
Wet firewood is not just an efficiency problem. It can smoke heavily, cool the firebox, and contribute to creosote buildup in the flue. EPA advises against burning wet or green wood and warns that smoldering fires are not safe or efficient safe operation.
Use the calculator to plan supply, but use your stove manual, local codes, and a qualified chimney professional for safety decisions. If smoke comes into the room, draft is poor, the flue has heavy deposits, or you smell smoke after switching to dry wood and opening the damper, stop treating it as a math problem. Appliance condition and chimney performance need direct inspection.
Firewood can move insects and pathogens farther than they would travel on their own. The USDA National Invasive Species Information Center describes firewood movement as a major pathway for invasive pests and notes that some insects can survive in firewood for years firewood movement. USDA APHIS gives the practical version: do not move firewood, and buy or use firewood close to where you will burn it close to your campsite.
This does not change the BTU math, but it changes the buying decision. A distant high-BTU hardwood bargain may be a poor choice if it crosses pest-regulation boundaries or risks moving untreated wood into a new area. Local, seasoned, accurately measured firewood is usually the cleaner decision for both heat planning and landscape health.
The estimate is reliable enough when you know the species, the volume is measured as cords, the wood is dry or close to dry, and you are using the result for comparison. It is especially useful for planning how much to order, deciding whether a price is fair, and checking whether a partial stack can cover a short heating period.
It is less reliable when the species is unknown, the load is loose, the wood is freshly cut, the pile is mixed, or the seller uses a vague unit. It is also less reliable when you are trying to predict exact household heating duration. A windy farmhouse, a tight small cabin, and a masonry fireplace can consume the same stack at very different rates.
For household planning, pair the calculator with your own burn history. If you know that last winter used four measured cords of seasoned hardwood, that experience is more useful than a generic house-size estimate. The calculator then helps you translate a different species mix into a comparable heat supply. If you have no burn history, start with a conservative order, keep notes through the season, and avoid assuming that one chart can account for your climate, insulation, thermostat habits, and appliance setup.
If your first problem is stack volume rather than heat value, start with the /tools/firewood-cord-calculator/ and convert the pile into cords before estimating BTU. If the firewood came from your own property work, related tree tools such as /tools/tree-diameter-calculator/, /tools/tree-height-calculator/, and /tools/dbh-basal-area-calculator/ can help you keep tree measurements separate from fuel planning.
For broader outdoor planning, use the result alongside material calculators such as /tools/soil-volume-calculator/, /tools/compost-calculator/, and /tools/dirt-topsoil-calculator/ when a property project includes both wood cleanup and planting-bed work. Firewood BTU is only one part of the yard workflow; hauling, stacking, soil repair, mulch, and planting space often matter just as much.
The first mistake is entering a face cord as a full cord. If the depth is 16 inches, the stack is often about one-third of a cord, not one cord. The second mistake is ignoring moisture. A wet cord may look like a bargain and still deliver disappointing heat because water is taking up weight, drying time, and combustion energy.
The third mistake is comparing species without comparing price. A lower-BTU species at the right price can be sensible; a high-BTU species at a premium price can be poor value if it is wet, short-loaded, or too far away. The fourth mistake is expecting a calculator to replace experience. Your stove habits, house tightness, climate, and chimney draft are local variables the tool cannot see.
Before ordering, ask for the species mix, the measured unit, the log length, the drying history, and whether the wood is split. Ask whether the price includes delivery and stacking. If the unit is not a full cord, ask for all three dimensions so you can convert it.
When the wood arrives, measure the stack after it is neatly piled. Check moisture on a freshly split face. Keep notes on supplier, species, price, estimated cords, moisture reading, and how the wood burned. After one season, those notes are better than any generic chart because they connect the calculator’s estimate to your house and stove.
The Firewood BTU Calculator is best used as a comparison tool. Enter the species, convert the stack to cords, and read the result as estimated heat stored in the wood. Then adjust your confidence based on moisture, appliance efficiency, storage quality, and how accurately the wood was measured.
The strongest firewood plan combines three simple checks: use a tape measure for volume, use a moisture meter for dryness, and use BTU per cord to compare species and price. When those three agree, the calculator gives you a practical number for ordering, budgeting, and deciding whether the stack in front of you is enough for the season.
This Firewood BTU Calculator was researched and written by . Logic, safety notes, and result copy for Firewood BTU are reviewed against LeafyPixels plant-care data, extension references, and veterinary toxicity sources where pet safety is involved.
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The LeafyPixels editorial team then reviews the draft for clarity, step-by-step usefulness, and fit with real apartment and home conditions-not ideal greenhouse setups. When guidance changes materially, we update the page and note the revision date.
Total BTU = Cords x Species BTU per cord. BTU values from the USFS Forest Products Lab (FPL) for seasoned (20 percent moisture) wood. Sample values: shagbark hickory 27.7M BTU/cord, white oak 24.6M, red oak 24.0M, hard maple 23.5M, white ash 23.2M, yellow birch 22.8M, red maple 21.8M, beech 23.7M, cherry 20.4M, black locust 27.0M, osage orange 26.8M, white pine 15.5M, balsam fir 15.0M, spruce 15.0M, aspen 15.0M, basswood 14.5M. Result is rounded to the nearest 0.1 million BTU. Green (unseasoned) wood produces 30 to 40 percent less heat - multiply by 0.65 to estimate green-wood BTU from the seasoned value.
The long-form review for this page covers Firewood BTU Calculator. Its bottom source list includes 7 external citations pulled from the long-form guide, then deduplicated with the tool’s frontmatter sources.
Among common North American firewoods, the highest-BTU species are: shagbark hickory (27.7 million BTU per cord), black locust (27.0), osage orange (26.8), white oak (24.6), red oak (24.0), beech (23.7), hard maple (23.5), white ash (23.2), yellow birch (22.8), and red maple (21.8). The lowest-BTU common firewoods are: white pine (15.5), balsam fir (15.0), spruce (15.0), aspen (15.0), and basswood (14.5). The difference between the best and worst common species is about 90 percent - a cord of hickory provides almost twice the heat of a cord of pine.
A cord of seasoned white oak produces 24.6 million BTU. A cord of seasoned red oak produces 24.0 million BTU. These values are for fully seasoned wood (under 20 percent moisture content) measured by the USFS Forest Products Lab. Green (unseasoned) oak produces about 18 to 20 million BTU per cord because some of the heat is lost to evaporating water. A modern EPA-certified wood stove extracts about 70 to 80 percent of that heat into the room, so a cord of oak through an efficient stove delivers about 17 to 20 million BTU of usable heat.
A typical 2,000 sq ft home in a cold climate (zone 5 to 6) needs 60 to 90 million BTU of heating per winter. This is the heat load through the walls, roof, and windows plus the heat lost to ventilation. A high-efficiency wood stove delivers about 70 to 80 percent of the wood’s BTU as useful heat, so 60 to 90 million BTU needs about 3 to 4 cords of seasoned oak or hickory. A mild climate (zone 3) needs 30 to 50 million BTU, or 1.5 to 2.5 cords. The exact number depends on insulation, house orientation, and thermostat setting.
Wood moisture has a huge effect on usable heat. Wet wood (50 percent moisture, freshly cut) produces about 8 to 10 million BTU per cord - half of which is lost to evaporating the water in the wood. Properly seasoned wood (20 percent moisture) produces 18 to 25 million BTU per cord depending on species. Kiln-dried wood (10 percent moisture) produces 22 to 28 million BTU per cord. The best return comes from seasoning wood to 15 to 20 percent moisture, which takes 6 to 12 months of air drying. Use a moisture meter to confirm before burning.
Softwood (pine, spruce, fir) is less energy-dense than hardwood - a cord of pine produces about 15 million BTU versus 24 million for oak. The advantage of softwood is that it is cheaper, easier to split, and seasons in 4 to 6 months versus 9 to 12 for hardwood. Softwood is also a good choice for shoulder-season heating (spring and fall) when you only need occasional fires. The disadvantage of softwood is that it produces more creosote (the tar that builds up in chimneys and causes chimney fires), so softwood requires more frequent chimney cleaning.
Store firewood split, stacked, and off the ground. Splitting exposes more surface area to air, so the wood seasons faster. Stacking in single rows (not solid piles) allows air to circulate. Pallets or 2x4s under the stack keep the wood off wet ground. Stack the bark up and the cut ends exposed. Cover the top to keep rain off but leave the sides open. A south-facing, breezy location is ideal. Properly stored, firewood reaches 15 to 20 percent moisture in 6 to 12 months, which gives the highest BTU per cord.
The most cost-effective firewood is local, seasoned hardwood. Local wood avoids the transportation cost (a cord of oak weighs 3,000 pounds, so shipping is expensive). Seasoned hardwood gives the most heat per dollar because it has the highest BTU per cord. Avoid kiln-dried or ‘premium’ firewood sold at gas stations and convenience stores - they are 3 to 5 times more expensive per million BTU than bulk local firewood. The exception is if you only need a small amount for occasional fires, in which case the convenience of small bundles may be worth the premium.