Home BTU Chart
BTU to Sq Ft Chart — Heating & Cooling by Room Size
Use this BTU to square feet chart to compare room cooling capacity, heating planning ranges, AC tonnage, and common equipment sizes. The window-AC references follow current ENERGY STAR room-sizing guidance; whole-home heating and cooling figures are clearly marked as planning references, not Manual J equipment sizing.
Reviewed for 2026 with current ENERGY STAR room-AC guidance and ACCA load-calculation references.
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 more detailed room estimate. For BTU rates by square foot, see BTU per square foot.
The 30-second BTU chart
Room AC: ENERGY STAR recommends 5,000 BTU/h for 100–150 sq ft, 8,000 for 300–350 sq ft, 12,000 for 450–550 sq ft, and 18,000 for 700–1,000 sq ft.
Heating: square-foot rules are only planning references—final heating equipment sizing should use a load calculation.
1 ton of cooling = 12,000 BTU/h.
Firewood: heat per cord varies substantially by species and moisture content. Use the interactive lookup below for the detailed charts.
Ready to shop by size?
Room/home values are planning references based on simplified square-foot rates, not an IECC or Manual J load calculation. For equipment purchase decisions, use the advanced BTU calculator as a screening tool and request an ACCA Manual J calculation for whole-home sizing.
BTU by square footage — cooling reference and heating planning range
The table below is designed for fast comparison. Cooling values for room-size equipment should be checked against the ENERGY STAR room-air-conditioner chart. Heating values are only broad planning ranges because a standards-based heating load depends on outdoor design temperature, insulation, windows, air leakage, orientation, and other building details.
Use this chart to narrow the equipment class, then use the dedicated calculator for the equipment type. For a whole home, ACCA Manual J is the recognized residential load-calculation standard and should replace square-foot rules of thumb.
| 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
ENERGY STAR publishes a room-air-conditioner sizing chart based on floor area and an 8-foot ceiling. Its adjustment guidance says to reduce capacity 10% for heavy shade, increase 10% for a very sunny room, add 600 BTU/h for each regular occupant beyond two, and add 4,000 BTU/h for a kitchen.
Avoid oversizing a room air conditioner. Correct capacity improves comfort and efficiency; use the dedicated window AC calculator for window dimensions and electrical checks.
| 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.
BTU chart methodology and sources
The room-air-conditioner chart and its sun, occupant, and kitchen adjustments follow ENERGY STAR guidance. Whole-home heating/cooling square-foot figures are planning references only; ACCA Manual J is the recognized residential load-calculation standard. Firewood values are comparative dry-cord references based on forestry extension data and can vary with moisture and stacking.
Frequently asked questions
What BTU do I need for my room size?
For room air conditioning, ENERGY STAR recommends 5,000 BTU/h for 100–150 sq ft, 8,000 for 300–350 sq ft, 12,000 for 450–550 sq ft, and 18,000 for 700–1,000 sq ft before its sun, occupant, and kitchen adjustments. Heating cannot be sized reliably from square footage alone.
What is the firewood with the highest BTU?
Dense hardwoods generally provide more heat per cord than lower-density species. The firewood chart above is a comparative dry-cord reference; actual usable heat changes with species, moisture content, stacking, and appliance efficiency.
How many BTU is a cord of firewood?
There is no single BTU value for a cord. Heat content varies substantially by wood species and moisture. A full cord is 128 cubic feet of stacked wood and air space; use the species chart above as a comparative reference rather than a guaranteed delivered-heat value.
What size BTU air conditioner do I need?
Use the ENERGY STAR room-size chart for a window or room AC, then adjust for shade, sun, occupants, and kitchens. Whole-home central AC should be selected from a load calculation rather than a simple square-foot-to-BTU conversion.
What does 1 ton of AC equal in BTU?
1 ton of cooling equals 12,000 BTU per hour. A 2-ton system is 24,000 BTU/h and a 3-ton system is 36,000 BTU/h. Tonnage is capacity, not a square-foot guarantee.
What is a BTU chart for natural gas?
Fuel BTU tables compare energy content before equipment efficiency losses. Delivered heat depends on the appliance efficiency, so use fuel-energy values for cost comparisons rather than as a direct room-sizing method.
How many BTU per square foot for heating?
There is no standards-based heating BTU-per-square-foot number that works for every home. Square-foot rates can be used only as rough planning ranges; final equipment sizing should account for local design temperature, insulation, windows, infiltration, ductwork, and other load factors.
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