HVAC Load Calculator (Tons)
Total HVAC cooling load combines sensible heat (temperature change) and latent heat (moisture removal), then converts BTU/hr to tons of refrigeration. 1 ton = 12,000 BTU/hr, which...
Formula
Source: Engineering Toolbox, ASHRAE Fundamentals | Last reviewed: June 8, 2026
Examples
0 ton
= 0.95 ton
- cfm = 400
- delta_T = 20
- delta_W = 10
400 CFM, 20°F ΔT, 10 gr/lb ΔW = 0.95 tons (~1 ton system)
0 ton
= 5.28 ton
- cfm = 1200
- delta_T = 30
- delta_W = 30
1,200 CFM with high latent load = 5.28 tons
0 ton
= 4.17 ton
- cfm = 2000
- delta_T = 20
- delta_W = 5
2,000 CFM with low humidity = 4.17 tons
Where is this used?
Building load estimation: preliminary cooling load for conceptual design phase.
Energy audit analysis: comparing installed capacity to calculated load.
System replacement sizing: verifying that replacement equipment is appropriately sized.
Frequently Asked Questions
How accurate is this calculator for real buildings?
This is an air-side load calculation based on coil entering and leaving conditions. It does not account for building envelope loads, solar gain, internal loads (people, lights, equipment), or duct losses. For full building load calculations, use Manual J (residential) or Manual N/ASHRAE Heat Balance Method (commercial).
What is a typical tons per CFM ratio?
A common rule of thumb is 400 CFM per ton for comfort cooling. That is, 1 ton of cooling capacity for every 400 CFM of supply air. At this ratio: 400 CFM × 20°F ΔT × 1.08 = 8,640 BTU/hr sensible, plus latent ≈ 12,000 BTU/hr total = 1 ton. This 400 CFM/ton rule underlies most HVAC air distribution design.
Should I size equipment exactly to this calculation?
No. Add safety factors (typically 10-15%), consider part-load performance, and never grossly oversize cooling equipment — oversized equipment short-cycles, provides poor humidity control, and reduces efficiency. Proper Manual J or energy modeling is essential for final equipment selection.
Reviewed for accuracy
· Last reviewed: June 8, 2026
All calculations are for reference only. Always verify with manufacturer data and a qualified engineer for critical applications. Learn about our editorial process.