How to use the BTU Calculator
The BTU calculator estimates the cooling capacity a room needs.
What you need to enter
- Room area (sq ft)
- Ceiling height (ft)
- Sun exposure
- Occupants
- Kitchen?
The formula
Base BTU = area × 20, adjusted for ceiling height, sun exposure, occupants and a kitchen.
Worked example
Using the default values in the calculator:
- Room area (sq ft): 300
- Ceiling height (ft): 8
- Sun exposure: Normal
- Occupants: 2
- Kitchen?: No
| BTU / hour needed | 6,000 |
| Tons of cooling | 0.5 |
| Watts | 1,758 |
Tips for better results
- Round to the nearest available unit size.
- Oversized units cool poorly.
Common mistakes to avoid
- Ignoring insulation and windows.
- Choosing a unit that is too large.
Please note: Results are estimates for general use. For safety-critical work such as electrical or building projects, check with a qualified professional and local codes. See our Disclaimer.