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Portable Air Conditioner Calculator

Estimate the practical BTU range for a portable air conditioner from room size, climate, exposure, insulation and usage.

Room dimensions

Measure the room you actually want to cool, not the whole floor or apartment.

Recommended portable AC

7,000 BTU
Shopping range7000-8000 BTU
Approx. effective cooling5300 BTU
Estimated power draw650 W
Room sizemedium
Cooling difficultyeasy

Location and climate

Usage and heat load

How to use this result

Recommended cooling capacity: 7,000 BTU

  • Room area: 16 m2 / 40 m3.
  • Base estimate uses about 20 BTU per square foot, then adjusts for ceiling height, climate, sun exposure and insulation.
  • Room use is included in the final cooling load.
  • Dual-hose or well-vented portable AC units usually keep more effective cooling in the room.

Before buying

  • Portable AC ratings vary by test method. Compare marketed BTU and real-world reviews, not only the largest number on the box.
  • A unit that is much too large may cool quickly but remove less humidity, which can feel clammy.
  • Good window sealing and a short exhaust hose can matter as much as buying a larger unit.
  • For bedrooms, also compare noise level, sleep mode and minimum fan speed.

Buying shortcut

From sizing to a realistic shortlist.

Use the calculator to avoid buying too small, then compare product picks with the right capacity, output power and use case in mind.

Open calculatorSee product picksRead the guide

Frequently asked questions

Is a bigger portable air conditioner always better?

No. Too much capacity can cool the room quickly but remove less humidity, while also being louder and less efficient.

Why does the calculator ask for location?

The city or region helps you choose a summer climate profile. A sunny Mediterranean room needs more cooling margin than a shaded room in a milder climate.

Why do portable AC units need extra margin?

Single-hose units exhaust indoor air and window kits are rarely perfect. A little margin helps compensate for heat entering through the hose and window seal.

Should I compare marketed BTU or effective BTU?

Use marketed BTU to shop within common product ranges, but read reviews and specs carefully because portable AC effective cooling can be lower in real rooms.

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Continue with the most relevant calculator or guide.

HomeSpecLab works best when calculators, buying guides and product picks reinforce each other. Use these links to move from sizing to shopping criteria.

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