Air conditioner BTU calculator

Non-positive room area is rejected with a clear invalid_input error instead of inventing a load from zero or negative square footage.

How room cooling BTU capacity is estimated

A widely used rule of thumb starts from floor area: multiply square footage by twenty BTU per square foot to get a base load for a typical residential room with an eight-foot ceiling and average solar gain. That base alone is not enough when the room is taller, sunnier, or more crowded than the baseline assumptions. The response also reports tons as cooling BTU divided by twelve thousand (one refrigeration ton), and recommended_btu as the cooling figure rounded up to the next five-hundred BTU step so you can match common window and portable AC product sizes. This is sizing guidance for shopping and planning, not a Manual J load calculation with insulation R-values, duct losses, or climate-zone design temperatures; treat the output as a transparent starting point and upsize or downsize when an engineer or manufacturer table says otherwise.

How to call the API and what comes back

Ceiling height, when provided, must also be positive and within limits; occupants must be a positive whole number. Prefer sending numbers rather than pre-formatted strings when you control the client; when you must send strings, avoid unit suffixes or thousand separators that would fail the finite-number pattern. Send a JSON body with required area in square feet (aliases room_area, sqft, square_feet, floor_area, A) and optional ceiling_height in feet (aliases height, ceiling, ceiling_ft, H; default eight), sun_exposure as shaded, average, or sunny (aliases sun, exposure, sunlight; also accepts shade/low, medium/normal, high/bright; default average), and occupants as a positive integer (aliases people, occupancy, persons, n; default two). Area must be a finite positive number within the published absolute range so intermediate products remain finite in IEEE double precision on the Worker and in the browser. Non-positive area is the primary hard error this capability advertises: zero or negative square footage cannot define a room load and returns invalid_input. On success the response echoes rounded area, ceiling_height, sun_exposure, and occupants; publishes base_btu_per_sqft (always twenty), base_btu, height_factor, sun_factor, occupancy_adjustment_btu, cooling_btu and btu (same total), recommended_btu, tons, unit as BTU/h, formula as the human-readable equation string, message as a short English summary, and steps as an ordered array of substitution lines. Failed validation—missing area, non-finite numbers, non-positive area, invalid sun labels, non-integer or non-positive occupants, or values outside absolute limits—returns invalid_input and is never charged. Pricing is a flat $0.002 per successful request with unit item and zero marginal unit price.

Practical tips, limits, and related searches

When teaching or writing tests, pair a default eight-foot average room with a tall sunny high-occupancy case, and include a deliberate zero or negative area to prove the invalid_input path. This landing targets people searching for an air conditioner BTU calculator, room cooling capacity, AC size by square feet, or ceiling height and sun exposure adjustments online; it is not a full whole-house Manual J load program, not a heat-pump heating BTU tool, not a SEER or energy-cost estimator, and not a duct-sizing calculator. Failed tasks that return invalid_input do not consume prepaid balance, which keeps exploratory scripts cheap when you deliberately send area zero to verify error handling. Round-trip checks are easy: recompute area times twenty, multiply by height over eight and by the sun factor, add six hundred times extra people, and confirm the published cooling_btu matches within the same twelve-decimal rounding used for all numeric fields.