BTU Chart
Quick-reference BTU charts for every use case: room and home sizing, window AC selection, firewood heat content by species, and equipment tonnage. Use the interactive lookup to filter for your situation, then jump to the right sizing calculator.
Updated for 2026. All HVAC BTU rates aligned with IECC climate zone standards.
On this page: Interactive BTU lookup · BTU by room size · Window AC chart · Firewood BTU chart · Tonnage chart · FAQ
Need a calculated result, not just a chart? The advanced BTU calculator adds climate zone, ceiling height, windows, sun exposure, and duct losses for a precise room estimate. For BTU rates by square foot, see BTU per square foot.
The 30-second BTU chart
Room cooling: ~20 BTU per sq ft in Zone 4. A 300 sq ft room needs ~7,500 BTU.
Home heating: ~40 BTU per sq ft in Zone 4. A 2,000 sq ft home needs ~80,000 BTU.
Firewood: Red oak = ~24M BTU per cord. White pine = ~16M BTU per cord.
1 ton AC = 12,000 BTU. Use the interactive lookup below
to filter these charts for your climate zone and situation.
Assumes 8 ft ceilings and moderate sun. For adjustments, use the room-type estimator or advanced BTU calculator.
BTU chart by room size — cooling and heating
This static reference table uses Zone 4 (NYC, DC, Seattle) and average insulation as the baseline — the most common US scenario. It gives both cooling and heating BTU for each room size band. For other climate zones, use the interactive lookup above or the BTU per square foot table.
Unlike a calculator, a chart lets you scan a range quickly — useful when you’re comparing equipment options or confirming that a contractor’s recommendation makes sense.
| Room / area size | Typical space | Cooling BTU (Zone 4) | Heating BTU (Zone 4) | AC tonnage | Equipment match |
|---|---|---|---|---|---|
| 100–150 sq ft | Small bedroom, den | 5,000–6,000 | 4,000–6,500 | — | 5K window AC |
| 150–250 sq ft | Bedroom, office | 6,000–8,000 | 6,500–10,000 | — | 8K window AC |
| 250–350 sq ft | Master bedroom, studio | 8,000–10,000 | 10,000–14,000 | — | 10K window AC |
| 350–550 sq ft | Living room, open studio | 10,000–14,000 | 14,000–22,000 | 1 ton | 12K mini split |
| 550–900 sq ft | Large living room, apt | 14,000–20,000 | 22,000–36,000 | 1.5 ton | 18K mini split |
| 900–1,200 sq ft | Small home, condo | 18,000–24,000 | 36,000–50,000 | 2 ton | 24K mini split |
| 1,200–1,600 sq ft | Average 2–3 BR home | 24,000–30,000 | 50,000–66,000 | 2.5 ton | Central AC / heat pump |
| 1,600–2,000 sq ft | Average 3 BR home | 30,000–36,000 | 66,000–80,000 | 2.5–3 ton | Central AC / heat pump |
| 2,000–2,500 sq ft | Larger 3–4 BR home | 36,000–42,000 | 80,000–100,000 | 3–3.5 ton | Central AC / heat pump |
| 2,500–3,000 sq ft | Large 4–5 BR home | 42,000–48,000 | 100,000–120,000 | 3.5–4 ton | Central AC / heat pump |
| 3,000+ sq ft | Large or luxury home | 48,000–60,000+ | 120,000+ | 4–5 ton | Central AC — get a quote |
Sizing calculators for specific equipment: Central AC · Furnace · Heat pump · Mini split · Window AC
Window AC BTU chart — by room size
The Energy Star window AC BTU chart recommends equipment size by room square footage. These figures assume average insulation and moderate sun in a Zone 4 climate. Add ~10% for kitchens (appliance heat), upper floors, or poor insulation. Subtract ~10% for heavily shaded north-facing rooms.
The most important rule: do not oversize a window AC. An oversized unit cools the air temperature quickly but runs too short a cycle to remove humidity, leaving the room feeling clammy even at the correct temperature.
| Room size | Recommended BTU | Watts (typical) | Monthly cost (est.) | Shop |
|---|---|---|---|---|
| Up to 150 sq ft | 5,000 BTU | 450–500 W | ~$10–12/mo | 5,000 BTU window ACs |
| 150–250 sq ft | 6,000 BTU | 540–600 W | ~$13–15/mo | 6,000 BTU window ACs |
| 250–350 sq ft | 8,000 BTU | 700–750 W | ~$16–18/mo | 8,000 BTU window ACs |
| 350–450 sq ft | 10,000 BTU | 900–1,000 W | ~$20–24/mo | 10,000 BTU window ACs |
| 450–550 sq ft | 12,000 BTU | 1,050–1,150 W | ~$24–28/mo | 12,000 BTU window ACs |
| 550–700 sq ft | 14,000 BTU | 1,300–1,400 W | ~$30–34/mo | 14,000 BTU window ACs |
| 700–1,000 sq ft | 18,000 BTU | 1,700–1,900 W | ~$40–45/mo | Mini split recommended |
Energy costs estimated at $0.16/kWh, Zone 4, 180 hrs/mo runtime. For bedroom cooling, consider a mini split (19–32 dB indoor, vs 52–58 dB for window ACs). Use the window AC calculator for a voltage check and window fit confirmation.
Firewood BTU chart — heat content by wood species
Firewood BTU (heat content) varies widely by species. Hardwoods are denser and contain significantly more energy per cord than softwoods. This matters for wood stove sizing, fuel cost comparisons, and deciding which wood to buy or season for winter.
What is a cord of firewood?
A standard cord measures 4 ft × 4 ft × 8 ft = 128 cubic feet of stacked wood (including air gaps). The actual wood volume is closer to 80–90 cubic feet; the rest is air. A face cord (also called a rick) is one-third of a full cord — the same 4 ft × 8 ft face but only as deep as the logs are cut, typically 16 inches.
All BTU figures below are for air-dried wood at approximately 20% moisture content. Freshly cut (green) wood contains 50% or more water and delivers roughly half the usable BTU — always burn seasoned wood for maximum heat output and minimum creosote buildup.
Top hardwood species by BTU per cord
| Wood species | Type | BTU per cord (millions) | Relative to red oak | Notes |
|---|---|---|---|---|
| Osage orange (hedge apple) | Hardwood | 32.9 | 137% | Highest BTU of any NA wood; splits difficult; sparks heavily |
| Shagbark hickory | Hardwood | 27.7 | 115% | Excellent heat; great for cooking; widely available |
| Black locust | Hardwood | 26.8 | 112% | Very dense; slow to ignite but long burn; rot-resistant |
| Apple | Hardwood | 27.0 | 113% | Pleasant smell; good coals; hard to find in large quantities |
| White oak | Hardwood | 29.1 | 121% | Top-tier hardwood; excellent coals; widely available |
| Red oak | Hardwood | 24.0 | 100% (baseline) | Most common benchmark hardwood; easy to split; good all-rounder |
| Sugar maple | Hardwood | 24.5 | 102% | Excellent heat; great coals; popular in Northeast US |
| Yellow birch | Hardwood | 21.8 | 91% | Good heat; sparks somewhat; easy to split |
| American beech | Hardwood | 24.0 | 100% | Similar to red oak; hard to split when green; excellent seasoned |
| Black walnut | Hardwood | 22.2 | 93% | Good heat; good coals; often saved for its lumber value |
| White ash | Hardwood | 23.6 | 98% | Splits easily even when green; good choice for beginners |
| American elm | Hardwood | 19.5 | 81% | Difficult to split due to interlocked grain; decent heat |
| Silver maple | Hardwood | 18.9 | 79% | Lower BTU than sugar maple; easy to split; common |
| Cottonwood / aspen | Hardwood | 13.5 | 56% | Low density; burns fast; best for shoulder-season or kindling |
Softwood species by BTU per cord
| Wood species | Type | BTU per cord (millions) | Relative to red oak | Notes |
|---|---|---|---|---|
| Douglas fir | Softwood | 20.7 | 86% | Best softwood for heat; common in Western US; good for stoves |
| Tamarack (larch) | Softwood | 19.6 | 82% | Deciduous softwood; excellent heat for a conifer; popular in North |
| Lodgepole pine | Softwood | 18.4 | 77% | Decent heat; widely available in Rockies; resin can cause creosote |
| Red pine | Softwood | 17.1 | 71% | Moderate heat; easy to split; sparks from resin |
| White pine | Softwood | 15.9 | 66% | Common but low BTU; good kindling; creosote risk at low burn temps |
| Spruce | Softwood | 15.5 | 65% | Low density; lights easily; best for quick heat or campfires |
| White cedar | Softwood | 12.2 | 51% | Very low BTU but easy to split; ideal kindling only |
Practical rule: if you want the heat of one cord of red oak, you need about 1.5 cords of white pine. Always buy firewood by species and by cord measurement, not by weight or loose volume. A high-efficiency wood stove rated at 60,000 BTU/hr running at 75% output delivers 45,000 BTU/hr — roughly equivalent to a 45,000 BTU propane heater.
BTU to tonnage chart — AC and heat pump sizing
Central air conditioning and heat pumps are sold by tonnage. One ton of cooling equals 12,000 BTU/hr — the amount of heat a ton of ice absorbs as it melts over 24 hours. Use this chart to convert between BTU and tons, and to confirm that a contractor’s proposed equipment size is in the right range.
| Tonnage | BTU per hour | Approx. sq ft (Zone 4) | Typical application |
|---|---|---|---|
| 1.0 ton | 12,000 BTU | 500–700 sq ft | Small condo, studio apartment |
| 1.5 ton | 18,000 BTU | 700–1,000 sq ft | Small home, large apartment |
| 2.0 ton | 24,000 BTU | 1,000–1,300 sq ft | Small 2–3 BR home |
| 2.5 ton | 30,000 BTU | 1,300–1,600 sq ft | Average 2–3 BR home |
| 3.0 ton | 36,000 BTU | 1,600–2,000 sq ft | Average 3 BR home |
| 3.5 ton | 42,000 BTU | 2,000–2,400 sq ft | Larger 3–4 BR home |
| 4.0 ton | 48,000 BTU | 2,400–2,800 sq ft | Large 4 BR home |
| 5.0 ton | 60,000 BTU | 2,800–3,500 sq ft | Large home; maximum residential single-unit size |
Square footage ranges are for Zone 4 with average insulation and 1–2 stories. Hot climates (Zone 1–2) reduce these ranges by ~15–20%. Cold climates do not change AC sizing but do require more furnace BTU per sq ft. Always confirm whole-home sizing with a Manual J load calculation.
Calculators: Central AC size · Heat pump size · Mini split size · Furnace size
Natural gas and propane BTU reference
Several keyword searches reach this page looking for natural gas BTU charts. While this site focuses on HVAC equipment sizing rather than gas pipe engineering, here is a practical reference for fuel BTU content used in heating load comparisons.
| Fuel | BTU per unit | Common unit | Notes |
|---|---|---|---|
| Natural gas | 100,000 BTU | Per therm | 1 therm = 100 cu ft of gas (approx). AFUE tells you how much you actually get as heat. |
| Natural gas | ~1,020 BTU | Per cubic foot | Varies slightly by region and gas composition. |
| Propane (LP) | 91,500 BTU | Per gallon | Propane is ~2.5× denser energy than natural gas per cubic foot. |
| Heating oil (#2) | 138,500 BTU | Per gallon | Highest BTU density of common residential fuels. |
| Electricity | 3,412 BTU | Per kWh | Heat pumps multiply this by COP (typically 2–4×) for delivered heat. |
| Wood pellets | ~8,000 BTU | Per pound | ~16M BTU per ton of pellets at 20% moisture. |
For gas pipe sizing charts (pipe diameter vs BTU flow rate), consult your local utility or the IFGC (International Fuel Gas Code) published by ICC. For comparing heating fuel costs per BTU: energy cost calculator.
Reduce your BTU requirement before buying equipment
Whatever chart number you find above, improving insulation and air sealing can reduce it by 20–30% — which means smaller, cheaper equipment. Weatherstripping ($5–15), door sweeps ($8–20), window film ($10–30), and spray foam ($10–40) for attic gaps pay back quickly in lower energy bills. A thermal leak detector ($30–50) shows you exactly where to seal first.
Frequently asked questions
What BTU do I need for my room size?
As a quick reference for Zone 4 (NYC, DC, Seattle) with average insulation: 150 sq ft needs about 5,000 BTU; 300 sq ft needs 7,500 BTU; 500 sq ft needs 11,000 BTU; 1,000 sq ft needs 20,000 BTU; 1,500 sq ft needs 28,000–30,000 BTU. See the full BTU by room size chart above, or use the interactive BTU chart to filter by your climate zone.
What is the firewood with the highest BTU?
Osage orange (hedge apple) has the highest BTU per cord of any North American wood at approximately 32.9 million BTU per cord. Other top performers include white oak (29.1M BTU), shagbark hickory (27.7M BTU), and black locust (26.8M BTU). Red oak is the most common benchmark at 24.0M BTU per cord. See the full firewood BTU chart above for 20+ species.
How many BTU is a cord of firewood?
A cord of firewood ranges from about 12–33 million BTU depending on species. Average hardwoods (oak, maple, ash) deliver 22–26 million BTU per cord. Softwoods deliver 12–21 million BTU per cord. These figures are for air-dried wood at ~20% moisture. Green wood delivers roughly half the usable BTU.
What size BTU air conditioner do I need?
For a window AC: up to 150 sq ft → 5,000 BTU; 250 sq ft → 6,000 BTU; 350 sq ft → 8,000 BTU; 450 sq ft → 10,000 BTU; 550 sq ft → 12,000 BTU. For whole-home central AC, see the tonnage chart above. Use the window AC calculator for a complete sizing check including voltage compatibility and window dimensions.
What does 1 ton of AC equal in BTU?
1 ton = 12,000 BTU/hr. This unit comes from the era of ice cooling: one ton of ice melting over 24 hours absorbs 12,000 BTU/hr of heat. A 2-ton AC removes 24,000 BTU/hr; a 3-ton removes 36,000 BTU/hr. See the BTU to tonnage chart above for the full conversion table.
What is a BTU chart for natural gas?
Natural gas contains approximately 1,020 BTU per cubic foot, or 100,000 BTU per therm. Propane contains 91,500 BTU per gallon. Heating oil contains 138,500 BTU per gallon. These are the input BTU values — the heat delivered to your home depends on your furnace’s AFUE efficiency. See the fuel BTU reference table above. For gas pipe sizing, consult the IFGC or your local utility.
How many BTU per square foot for heating?
Zone 4 (NYC, DC, Seattle) averages 36–44 BTU/sq ft for heating with average insulation. Zone 5 (Chicago, Boston) needs 42–52 BTU/sq ft. Zone 6 (Minneapolis) needs 48–60 BTU/sq ft. See the full BTU per square foot table for all zones and insulation levels.
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