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AC Size Calculator

Recommends an air conditioner size in tons and BTU from room area, sun exposure, occupants, ceiling height and climate.

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Enter your figures and press Calculate.
In short AC Size Calculator is a free online tool on inputtesthub.com that recommends an air conditioner size in tons and BTU from room area, sun exposure, occupants, ceiling height and climate. It needs no account, no download and no payment, and there is no daily usage limit. Everything is processed inside your own browser, so the data you paste is never uploaded to a server.

How to use the AC Size Calculator

  1. Enter your figures in the input fields.
  2. The result updates as you type, together with the full working.
  3. Check the breakdown table to see exactly how the number was reached.

About the AC Size Calculator

The AC Size Calculator recommends an air conditioner size in tons and BTU from room area, sun exposure, occupants, ceiling height and climate. It runs as plain JavaScript inside the page, which means there is no upload step, no queue and no size limit imposed by a server — the only limit is your own device.

What people use it for

  • Choosing between a 1 ton and a 1.5 ton unit.
  • Checking a shop’s recommendation before buying.
  • Sizing for a room that gets strong afternoon sun.

Details

1 ton12,000 BTU/h
Hot climate≈ 1 ton per 120–150 ft²
Temperate, insulated≈ 25 BTU/h per ft²
Each extra person+600 BTU/h
Kitchen+4,000 BTU/h

The maths behind it

This tool uses Base load = floor area in ft² × a climate rate — 90 BTU/h per ft² where summers are very hot, 25 where they are temperate and buildings are insulated. Adjusted for sun, occupants beyond two, kitchen heat and ceiling height. 12,000 BTU/h = 1 ton. Every intermediate value is shown on screen, so the result can be checked by hand.

Bigger is not better. An oversized unit cools the air fast, hits the thermostat and shuts off before removing humidity, so the room feels cold and clammy and the compressor wears out from short-cycling.

Frequently asked questions

What size AC do I need for a 12 × 14 room?
That is 168 ft², so roughly 3,400 BTU/h base, adjusted upward for sun, occupants and climate — usually a 1 ton unit in a temperate climate and 1.5 ton where summers are very hot. Enter your own room above.
Is a bigger AC better?
No. An oversized unit reaches the set temperature before it has dehumidified the room, then shuts off. You get a cold, damp room and a compressor that short-cycles and fails early.
Is the AC Size Calculator free?
It is free, with no account, no trial and no daily cap. Every calculators tool on inputtesthub.com works the same way: open the page and use it.
Is the AC Size Calculator safe to use with private information?
No. The AC Size Calculator runs entirely in your browser using JavaScript. Nothing is transmitted, logged or stored, which you can verify yourself in the Network tab of your browser's developer tools.
What is the equation behind the AC Size Calculator?
It uses Base load = floor area in ft² × a climate rate — 90 BTU/h per ft² where summers are very hot, 25 where they are temperate and buildings are insulated. Adjusted for sun, occupants beyond two, kitchen heat and ceiling height. 12,000 BTU/h = 1 ton. The full working is printed under the result, so you can follow every step rather than trusting a black box.
Who is the AC Size Calculator for?
The most common reasons people reach for it: choosing between a 1 ton and a 1.5 ton unit. Checking a shop’s recommendation before buying. Sizing for a room that gets strong afternoon sun. It is built for exactly those cases rather than being a general-purpose tool with this bolted on.
Any caveats I should know about?
Bigger is not better. An oversized unit cools the air fast, hits the thermostat and shuts off before removing humidity, so the room feels cold and clammy and the compressor wears out from short-cycling.
What are the reference figures here?
1 ton is 12,000 BTU/h. Hot climate is ≈ 1 ton per 120–150 ft². Temperate, insulated is ≈ 25 BTU/h per ft². These are printed on the page itself, so you do not have to take them on trust.
Is the number rounded?
The calculation runs in double precision and the result is shown to ten significant figures, so converting a value and converting it back returns the original. What is displayed is rounded for readability; what is copied is not.

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