How many BTUs do I need for a 700 sq ft room?

For a 700 sq ft room, you generally need 14,000 to 15,000 BTUs per hour. If the room has high ceilings or heavy sun exposure, you may need to increase this to 18,000 BTUs.

What is the BTU per person rule?

The standard HVAC rule is to add 600 BTUs for every person in a room beyond the first two occupants. This accounts for the metabolic heat generated by the human body.

What does 1 ton of AC mean?

One ton of air conditioning is equal to 12,000 BTUs per hour. This is the amount of heat required to melt one ton of ice in 24 hours.

How many BTUs for a 12x12 room?

A 12x12 room (144 sq ft) typically requires a 5,000 BTU air conditioner. This is perfect for small bedrooms or home offices.

BTU Calculator for Room Size (AC Cooling)

BTU Calculation Formula

BTU/hr = Room Area (sq ft) × 20
+ 600 BTUs for each person beyond two
+ 4,000 BTUs if the room is a kitchen

Calculations follow standard residential HVAC sizing practices used by installers and ASHRAE-based guidelines.

Room BTU Calculator

Recommended Capacity:

-- BTU/hr

-- Tons

Quick BTU Guide

Room Size	BTU Needed
12x12 room	5,000 BTU
15x20 room	9,000 BTU
20x20 room	12,000 BTU
700 sq ft	15,000 BTU
1000 sq ft	18,000 BTU

*Standard 8ft ceilings. Adjust for sun/people.

BTU Sizing Guide: Getting it Right

How many BTUs for 700 sq ft?

A 700 sq ft room requires a capacity of approximately 15,000 BTU/hr. However, if the space is a "studio" layout with a kitchen, you should add an additional 4,000 BTUs to compensate for appliance heat. For spaces like a 700 sq ft basement, you can often drop down to 12,000 BTUs due to natural insulation.

BTU for 12x12 room size

A 12x12 room is 144 square feet. The base requirement for a space this size is 5,000 BTUs. This is the most common size for window AC units and is ideal for bedrooms. If the room has a 10ft ceiling, consider bumping up to 6,000 BTUs.

BTU Per Person: The "Occupancy Load"

The human body is essentially a 100-watt heater. For HVAC calculations, we use 600 BTUs per person. If you are calculating capacity for a home office where 1 person works, the standard calculation holds. If you are sizing a conference room or living room for 6 people, you must add 2,400 BTUs (600 x 4 extra people) to the total.

What is 1 Ton of AC?

In the HVAC world, "1 Ton" does not refer to the weight of the unit. 1 Ton of AC = 12,000 BTUs per hour. This unit of measurement is based on the amount of cooling required to melt one ton of ice over 24 hours. Most central AC units are sized in 0.5-ton increments (e.g., 2.5 tons = 30,000 BTUs).

Frequently Asked Questions

How do I calculate BTU for a room?

Multiply the Square Footage (Length x Width) by 20. Then add 600 BTUs for every person beyond two, and add 4,000 if the room is a kitchen.

Is a higher BTU always better?

No. If a unit has too many BTUs for the room size, it will "short cycle," turning off before it has a chance to dehumidify the air, leaving the room feeling cold but clammy.