HVAC & Energy
Mini-Split Size Calculator
Use a room-cooling screening chart for a first comparison, or enter known design loads from a proper assessment. Keep heating demand separate and compare nominal size bands without treating them as guaranteed equipment output.
Change any input to update the calculation. Unit changes preserve the physical quantity.
Inputs
Chart baseline is 8 ft. Higher ceilings use an explicit proportional scenario adjustment; no reduction below 8 ft.
Scenario input, not a climate-zone standard. Leave at 1 without a justified project adjustment.
Scenario input, not a substitute for envelope heat-gain analysis.
Add only gains not already represented by the base chart and other adjustments; avoid double counting.
Enter 0 to omit heating. Use Heat Loss or a qualified load assessment; area screening does not estimate heating demand.
Calculated locally in your browser. No sign-up or input upload.
Results
Screened / entered cooling load
2.051 kW7,000 BTU/hEntered heating load
0 kW0 BTU/hLarger load for nominal comparison
2.051 kW7,000 BTU/hNext listed nominal capacity band
9,000 BTU/h2.638 kWNominal band above comparison load
28.571 %Base room cooling chart value
2.051 kW7,000 BTU/hCalculation breakdown
- Heating input
- Heating load not entered; the comparison covers cooling only
Assumptions & checks
Preliminary room-cooling screen only. This is not Manual J, a climate-zone design or a manufacturer mini-split selection. Latent humidity loads and cold-weather delivered heat need separate checks.
Nominal BTU bands are comparison labels, not recommendations to oversize. Review modulation range, design-temperature capacity, distribution and equipment performance.
Formula
Room screen uses the ENERGY STAR room-AC area chart and stated sun, occupancy and kitchen adjustments. Ceiling, climate and insulation factors are transparent user scenarios. Mini-split delivered capacities still require manufacturer data.
Worked example
Using the default values shown in the calculator, the same formula gives the following result. This is a quick sanity check for the calculation, not a design recommendation.
Inputs
- Floor area
- 25 m²
- Ceiling height
- 2.4384 m
- Room sun exposure
- Typical
- Regular occupants
- 2
- Room includes a kitchen
- No
- User climate adjustment factor
- 1
- User insulation adjustment factor
- 1
- Additional window / equipment gain
- 0 W
- Known design heating load (optional)
- 0 kW
Result
- Screened / entered cooling load
- 2.051 kW
- Entered heating load
- 0 kW
- Larger load for nominal comparison
- 2.051 kW
- Next listed nominal capacity band
- 9,000 BTU/h
- Nominal band above comparison load
- 28.571 %
- Base room cooling chart value
- 2.051 kW
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Frequently asked questions
Can I use this as a Manual J calculation?
No. Area screening omits much of the envelope, latent load and climate detail required by a proper load calculation. Known-load mode is the better path when verified heating and cooling loads are available.
Why is heating not calculated from floor area?
Heating demand depends on envelope conductance, temperature difference and outdoor air. Enter a separate heating assessment rather than assuming it equals the room cooling screen.
Is the nominal band the heat delivered on a cold day?
No. Manufacturer capacity at the actual outdoor design temperature can differ from the nominal label. Check the equipment's extended performance data.
Reference data & method sources
- ENERGY STAR: room cooling screening chart
Room-air-conditioner screening at an 8-foot ceiling. Applied here only as a preliminary mini-split comparison, not Manual J or a certified mini-split design.
Reference tables
Room cooling chart upper boundaries
100–2,500 ft², 8-ft ceiling; lower bound inclusive and upper bound exclusive, except 2,500 is included. Room-AC screening, not a mini-split rating table.
| Upper area ft² | Base BTU/h |
|---|---|
| 150 | 5000 |
| 250 | 6000 |
| 300 | 7000 |
| 350 | 8000 |
| 400 | 9000 |
| 450 | 10000 |
| 550 | 12000 |
| 700 | 14000 |
| 1000 | 18000 |
| 1200 | 21000 |
| 1400 | 23000 |
| 1500 | 24000 |
| 2000 | 30000 |
| 2500 | 34000 |