AC & Heating BTU Calculator
A first-pass load estimate from floor area, ceiling height, insulation, sun exposure and occupancy. Use it to sanity-check a contractor's quote.
- Room volume
- 2016 cu ft
- Typical unit size
- 0.5 ton
- · This is an estimate, not a Manual J calculation. Ask your installer for the full load calculation.
- · Oversizing is worse than undersizing — it short-cycles and leaves the room humid.
How to use the AC & Heating BTU Calculator
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01
Measure the room floor dimensions and ceiling height.
-
02
Choose the closest description of sun exposure and insulation quality.
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03
Enter the usual number of occupants and identify whether the room is a kitchen.
-
04
Use the BTU figure to compare equipment, then ask an installer for a full load calculation.
Frequently asked questions
Is this a replacement for a Manual J calculation?
No. It is an early planning estimate. Equipment should be selected from a room-by-room professional load calculation.
Is a larger unit safer?
No. Oversized equipment can short-cycle, control humidity poorly and wear more quickly.
Can I calculate a whole house?
Calculate rooms separately. A whole-home system also depends on duct losses, air leakage, windows and local design temperatures.
Other tools
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Work out gallons of paint and primer for any room, including doors and windows.
Flooring Calculator
Boxes of flooring needed for any room, with a waste allowance for cuts and pattern.
Tile Calculator
Tiles, grout and adhesive for floors or walls, with breakage allowance.
Wallpaper Calculator
Rolls of wallpaper needed, accounting for pattern repeat.
These calculators give planning estimates based on the figures you enter. They are not a substitute for a site survey, a structural or load calculation, or professional advice. Always confirm quantities with your supplier or contractor before ordering.