Portable AC Sizing Calculator
BTU sizing for a portable air conditioner.
Enter your values
Enter the room area in sq ft.
Choose one of: Shaded, Average, Very sunny.
Choose one of: Single-hose, Dual-hose.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- 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
At a glance
| What it does | BTU sizing for a portable air conditioner. |
|---|---|
| Category | HVAC & Airflow |
| Inputs needed | Room area, Sun exposure, Hose type |
| Main output | Recommended rated BTU |
| Formula | BTU = area x 25 x sun factor x hose factor |
| Cost | Free — no sign-up, no download |
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.
Inputs explained
- Room area(sq ft)
- Enter the room area in sq ft.
- Sun exposure
- Choose one of: Shaded, Average, Very sunny.
- Hose type
- Choose one of: Single-hose, Dual-hose.
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.
What do I need to enter into the Portable AC Sizing Calculator?
Just 3 values: room area, sun exposure, hose type. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Portable AC Sizing Calculator work out the answer?
Portable ACs need roughly 20-25% more rated BTU than a split system for the same room because of single-hose exhaust losses. It applies the formula BTU = area x 25 x sun factor x hose factor and shows the working so you can check each step by hand.
Is the Portable AC Sizing Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.