Calculator
Portable AC Size Calculator
Estimate portable AC capacity from room inputs and understand SACC, ASHRAE BTU labels, hose losses, exhaust sealing and product label checks.
What is included
- • Instant browser-side calculation
- • Visible formula and assumptions
- • Practical result range instead of false precision
- • Common-size context for early product comparison
- • Copy result, share URL, CSV export and print/PDF workflow
What is not included
- • Whole-home Manual J, Manual S or Manual D design
- • Local code, permit or inspection approval
- • Electrical, refrigerant, gas, combustion or structural safety review
- • Mold remediation, health advice or moisture-source repair
- • Final product selection or installation approval
Sources and maintained assumptions
Sizing assumptions are centralized and show source URLs, check dates and notes.
- DOE Room Air Conditioners
Checked 2026-05-22. Used for room AC preliminary BTU rule, room-level sizing caveats and oversizing humidity cautions.
- DOE Portable Air Conditioners Test Procedure
Checked 2026-05-22. Used for portable AC SACC / label caveats.
- ENERGY STAR Certified Dehumidifiers
Checked 2026-05-22. Used for pints/day and product rating caveats.
- HVI Bathroom Ventilation
Checked 2026-05-22. Used for residential bathroom fan CFM rules and fixture model.
- ACCA Technical Manuals
Checked 2026-05-22. Used to define Manual J, Manual S and Manual D boundaries.
- EPA Mold and Indoor Air Guidance
Checked 2026-05-22. Used for mold and water intrusion disclaimers.
FAQ
Which HVAC calculator should I start with?
Use the AC BTU calculator for room cooling, the portable AC calculator when a unit lists SACC or multiple BTU ratings, the dehumidifier calculator for moisture control, and the CFM / ACH calculators for airflow estimates.
Why does the calculator show a range instead of one exact number?
Room comfort depends on ceiling height, windows, insulation, sun exposure, moisture sources, installation details and product labels. A range is more useful for early comparison than a pseudo-exact number.
Can I use this instead of Manual J or a contractor review?
No. These tools are for room-level preliminary estimates. Whole-home HVAC design, duct sizing, equipment selection, electrical work, combustion safety, mold remediation and code compliance require qualified review.
How should I choose between two common AC sizes?
Start with the calculator range, then check sun exposure, ceiling height, kitchen heat, insulation and the product label. If the room is humid, avoid sizing far above the calculated range because oversizing can cool quickly without removing enough moisture.
Does this work for central AC sizing?
No. The AC calculator is for room, window and portable AC estimates. Central systems need load calculations, duct review, airflow checks and installation-specific design.