Portable AC Sizing Calculator
BTU sizing for a portable air conditioner.
Enter your values
ⓘ Live results
Results
- Recommended rated BTU
- 9,375 BTU/hr
- Equivalent tons
- 0.78
- Note
- Single-hose units depressurise the room, pulling in unconditioned air
Quick answer
Portable ACs need roughly 20-25% more rated BTU than a split system for the same room because of single-hose exhaust losses.
BTU = area x 25 x sun factor x hose factor
How to use the Portable AC Sizing Calculator
- 1Measure the room's floor area.
- 2Adjust for sun exposure since glass adds significant load.
- 3Add a hose-type penalty — single-hose units need extra capacity to offset negative pressure infiltration.
Worked example
Using the values the calculator loads with:
Inputs
- Room area300 sq ft
- Sun exposureAverage
- Hose typeSingle-hose
Results
- Recommended rated BTU9,375 BTU/hr
- Equivalent tons0.78
- NoteSingle-hose units depressurise the room, pulling in unconditioned air
Frequently asked questions
Why do single-hose units need more BTU?
They exhaust room air outside without a matched intake, pulling warm outside air back in through gaps.
Can portable ACs replace central air?
Only for small or supplemental spaces — they are far less efficient per BTU than split systems.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.