HVAC & PLUMBING
HVAC BTU & Tonnage Sizer
Determine the required heating and cooling capacity for optimal efficiency.
How to Calculate HVAC BTU & Tonnage Sizer
This quick estimator starts with 20 BTU per square foot for an 8-foot ceiling, scales for ceiling height and selected insulation and sun-exposure multipliers, then adds 1,000 BTU per window. It rounds load up to the next 100 BTU and converts capacity to tons.
- Base load = floor area x 20 BTU per square foot; adjusted load = base load x (ceiling height / 8) x insulation factor x exposure factor + (windows x 1,000 BTU).
- Tons = rounded BTU load / 12,000 BTU per ton.
Frequently Asked Questions
Can this estimate replace a professional HVAC load calculation?
No. It is a simplified screening estimate. Equipment selection should account for climate, orientation, air leakage, insulation, ducts, occupants, and other details in a proper load calculation.
Why does the calculator ask about ceiling height and windows?
Its estimate scales the base floor-area load for ceiling height and adds a fixed allowance per window, while insulation and exposure adjust the load with selected multipliers.