BTU to Tons Converter
| BTU/h | Tons | kW cooling | Typical job |
|---|---|---|---|
| 9,000 | 0.75 | 2,637.6 | studio / bedroom mini-split |
| 12,000 | 1 | 3,516.8 | one-ton bedroom or office |
| 18,000 | 1.5 | 5,275.3 | large room / open plan |
| 24,000 | 2 | 7,033.7 | small home central |
| 36,000 | 3 | 10,550.5 | whole home / small commercial |
| 60,000 | 5 | 17,584.2 | rooftop package |
One anchor runs the whole air-conditioning shelf: 12,000 BTU per hour is one ton of cooling, which is 3.5 kilowatts of heat moved. The 9,000 BTU mini-split over the bedroom window is a three-quarter-ton unit; the 24,000 BTU system living in the hallway ceiling is two tons; the 60,000 BTU rooftop package is five. Type any one of the three units and the converter fills in the other two live.
The ton is the unit nobody explains at the store: it dates from the age when cooling literally meant ice - one ton being the cooling you got from a ton of ice melting over a day - and it survived because the first electric chillers replaced exactly that ice delivery. BTU/h is what the spec sheets print, tons are what the old-school contractors ask for, and kilowatts are what the electrical label and the rest of the world use. The table lines up every common size from a studio mini-split to a small commercial roof.
How to use
- Type the BTU/h from the spec sheet, the tonnage from a contractor's quote, or the kilowatts from the label - the other two appear instantly.
- Match the table for scale: bedrooms run 9k BTU, whole apartments 18-24k, small commercial 36k and up.
- Remember the direction of the electricity bill: kilowatts of cooling moved are not kilowatts of electricity drawn - a 3.5 kW-cooling unit draws about 1 kW.
Frequently asked questions
How many BTU is a ton of air conditioning?
Exactly 12,000 BTU per hour, which is also 3.517 kilowatts of heat moved. The odd number is frozen history: a ton of ice melting over 24 hours absorbs 288,000 BTU, and 288,000 divided by 24 hours is 12,000 per hour. Early refrigeration machines were sold as replacing so-many tons of ice delivery, and the unit rode into every spec sheet since.
What size is a 18000 BTU air conditioner in tons?
1.5 tons - divide BTU/h by 12,000. The common mini-split ladder reads cleanly in tons: 9,000 is three-quarter ton, 12,000 is one ton, 18,000 is one-and-a-half, 24,000 is two, 36,000 is three. Contractors say tons, boxes say BTU/h, and this converter keeps the quote honest when the two dialects meet over one air handler.
Is 3.5 kW of cooling the same as 3.5 kW of electricity?
No - and the difference is the whole efficiency story. A one-ton unit moves 3.5 kW of heat using roughly 1 kW of electricity, because a heat pump does not create cool, it relocates it; the ratio is the unit's EER or COP, printed on the energy label. The kilowatt on your bill is the drawn one; the kilowatt in this converter is the cooling moved. Both belong on the quote, and mixing them up flatters nobody.
Is a bigger BTU air conditioner better?
Oversizing is its own failure mode: a unit too big for the room cools fast, shuts off before it dehumidifies, and leaves the clammy cave feeling people wrongly blame on the machine. Sizing belongs to square footage, insulation and sun load - the site's BTU calculator runs that math; this page translates the answer between BTU, tons and kilowatts once you have it. Cool fast is not the same as cool right.
Why do window units skip tons entirely?
Convention follows scale: window and portable units live between 5,000 and 15,000 BTU/h - all under 1.25 tons - so tons would read as awkward fractions (0.4, 0.8), and the industry just speaks BTU. Tons take over around 2 tons and up, where central systems, mini-splits and commercial rooftop packages live. The converter spans the whole shelf, so a 10,000-BTU window unit and a 10-ton rooftop meet in the same table.