How many BTU for 500 square feet?
500 sq ft × 25 BTU = 12,500 BTU baseline. With average insulation, round up to a 12,000 or 18,000 BTU unit depending on sun and ceiling height.
What Size AC Do I Need?
Living rooms and open areas need more BTU per square foot than bedrooms — more windows, people, and electronics. Enter your space and toggle kitchen load if cooking appliances share the zone.
Space dimensions
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Sizing settings
Open floor plans and single-zone limits
One mini-split head can cool an open kitchen-living-dining area if airflow reaches all corners. Hallways and closed bedrooms off that zone may stay warm — our open floor plan sizing guide covers when one head is enough.
500 sq ft × 25 BTU = 12,500 BTU baseline — round up to 12,000 or 18,000 BTU depending on sun and ceiling height.
Occupants and kitchen load
Each person beyond the first two adds sensible heat. A range or oven running during dinner adds spike load — enable kitchen load in settings for combined kitchen-living spaces.
Electronics, TVs, and game consoles add smaller but real loads in media rooms — if the space feels warm with people and screens on, bump sun exposure or occupants rather than doubling BTU “just in case.”
Room-size examples (planning only)
12×12 living nook (~144 sq ft): often 9,000 BTU retail after load math. 15×20 open living (~300 sq ft) with kitchen load: commonly 12,000–18,000 BTU. 20×25 great room (~500 sq ft) with west glass: often 18,000–24,000 BTU or two heads.
These are DIY planning ranges. Whole-house permits and equipment selection need a Manual J from a licensed pro — use this page to shortlist sizes before you shop.
Climate and when Manual J is required
Hot-humid zones need longer run time for dehumidification — prefer right-sized inverter equipment over oversized window boxes. Dry desert heat is more about peak BTU than moisture.
If you are replacing a central system, adding a heat pump, or pulling a permit, stop at this estimate and hire Manual J. For winter heating load in a garage or furnace zone, see the garage heater BTU calculator or furnace BTU calculator.
Related guides
Frequently asked questions
Do people affect AC sizing?
Yes. Each person adds roughly 600 BTU of sensible heat beyond the first two occupants. Enter occupant count in project settings.
Should I size for the hottest day of the year?
Size for design conditions in your climate — not record heat waves. In hot-humid zones, consider upsizing one step or improving insulation instead.
Related calculators
HVAC Calculators · https://hvaccalculators.net/what-size-ac-do-i-need/