Window AC BTU Calculator
ENERGY STAR-style BTU sizing for window units with the standard room corrections.
Window units are fixed-speed: oversizing causes cold-clammy rooms. Pick the size that runs nearly continuously on a design day.
Formula
Window AC BTU Calculator is a free window ac btu for HVAC designers, technicians and energy auditors — instant, accurate and 100% client-side, with the governing formula and reference shown next to the result so the number can be defended, not just quoted.
About Window AC BTU Calculator
ENERGY STAR-style BTU sizing for window units with the standard room corrections. The calculation implements 20 BTU/ft² base, −10% shade, +600/person, +4,000 kitchen (ENERGY STAR table) (ENERGY STAR room AC sizing table). Window units are fixed-speed: oversizing causes cold-clammy rooms. Pick the size that runs nearly continuously on a design day.
How to use Window AC BTU Calculator
- 1Enter Room area in m².
- 2Enter Heavily shaded? (1 = yes (−10%)).
- 3Enter Is it a kitchen? (1 = yes (+4,000 BTU)).
- 4Enter Occupants above 2.
- 5Read Required capacity instantly — no submit button needed.
- 6Need US units? Flip the SI/Imperial toggle and every field converts.
Why use Window AC BTU Calculator?
- ✓Implements the standard formula — 20 BTU/ft² base, −10% shade, +600/person, +4,000 kitchen (ENERGY STAR table)
- ✓Reference cited on-page: ENERGY STAR room AC sizing table
- ✓One-click SI ⇄ Imperial toggle — values convert in place, physics stays in SI
- ✓Runs entirely in your browser — nothing uploaded, free forever
Frequently asked questions
What formula does the Window AC BTU Calculator use?+
It computes 20 BTU/ft² base, −10% shade, +600/person, +4,000 kitchen (ENERGY STAR table), per ENERGY STAR room AC sizing table. The formula is displayed under the result.
What should I keep in mind when using this calculator?+
Window units are fixed-speed: oversizing causes cold-clammy rooms. Pick the size that runs nearly continuously on a design day.
Is this based on ASHRAE methods?+
The calculations follow the standard ASHRAE/ISHRAE formulations cited under the result, simplified where industry practice does the same. For permit-grade design, confirm with the full code procedure.
Is the Window AC BTU Calculator free to use?+
Yes — completely free, no sign-up, no limits. It runs client-side in your browser, so inputs stay private and results are instant even on slow connections.
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