HVAC Tools
Ballpark tonnage & airflow for quick budgeting.
Rough Cooling Load
Fast estimate for quoting. NOT a substitute for a Manual J.
Cooling load
50,000
BTU/h
Size
4.17 ton
1 ton = 12,000 BTU/h
Airflow target
1,667
≈ CFM (400/ton)
Guide only — factor 20 (tight, mild) to 35 (leaky, hot). Real sizing needs a Manual J load calc that accounts for windows, orientation, infiltration, and duct losses. Oversizing short-cycles and hurts humidity control.
HVAC Quick Reference
- 1 ton of cooling = 12,000 BTU/h. Tons = BTU ÷ 12,000.
- Airflow rule of thumb: ~400 CFM per ton (350–450 depending on climate/coil).
- Rough factor: ~20–35 BTU/ft² — pick low for tight/new, high for leaky/hot-climate.
- Temp rise (heat): BTU/h = CFM × 1.08 × ΔT (°F) for standard air.
- Bigger isn't better: an oversized unit cools fast but leaves the room clammy — size to the load.
