Check the model number on the unit’s nameplate
Look for the BTU rating on the nameplate or manual
Divide the BTU rating by 12,000 to get tons
Use this conversion: 1 ton = 12,000 BTU/h
18,000 BTU/h = 1.5 tons
24,000 BTU/h = 2 tons
30,000 BTU/h = 2.5 tons
36,000 BTU/h = 3 tons
42,000 BTU/h = 3.5 tons
48,000 BTU/h = 4 tons
60,000 BTU/h = 5 tons
Check the owner’s manual or product spec sheet
Search the model number online
Ask the installer or HVAC technician
Look at the outdoor condenser and indoor air handler labels
Verify whether the listed capacity is cooling capacity, not electrical input