HVAC Size Calculator
Last updated: October 15, 2026
Estimate a rough heating and cooling capacity from floor area and basic adjustments.
Estimated HVAC capacity
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- Estimated BTU per hour: —
- Approximate cooling tons: —
- Planning range: —
On this page
Quick summary: Estimate a rough heating and cooling capacity from floor area and basic adjustments.
Read the complete guide
Updated reference sections in this guide are in English.
What this calculator estimates
Estimate a rough heating and cooling capacity from floor area and basic adjustments.
How to use it
Enter Conditioned floor area (sq ft); Climate load factor (BTU per sq ft); Ceiling-height factor; Regular occupants. Select Calculate to update the results.
How the calculation works
Illustrative cooling load in BTU/h = conditioned square feet × entered BTU/h per square foot × ceiling factor, plus 600 BTU/h for each occupant above two. Divide by 12,000 to convert BTU/h to refrigeration tons. The displayed comparison range is 90% to 110% of that result.
Worked example: starting scenario
| Conditioned floor area (sq ft) | 2000 |
|---|---|
| Climate load factor (BTU per sq ft) | 25 |
| Ceiling-height factor | 1 |
| Regular occupants | 4 |
| Estimated HVAC capacity | 4.27 tons |
|---|---|
| Estimated BTU per hour | 51,200 BTU/h |
| Approximate cooling tons | 4.27 |
| Planning range | 3.8–4.7 tons |
Important limitations
This is a rough editable sizing rule, not a room-by-room load calculation. Its 10% range is a comparison band, not a measured confidence interval. Insulation, air leakage, sun exposure, humidity, windows, ducts and local design temperatures require a proper load assessment before selecting equipment.