AC Tonnage Calculator
Enter a BTU load or your room/building's square footage directly and get the equivalent equipment size in tons, the standard unit used to select AC and heat pump equipment.
- Covers All 8 Stocked Refrigerants
- Built for Field Use
- No Login Required
- Updated for Current A2L Data
How the Tonnage Calculator Works
Three steps between you and a verified saturation reading no chart flipping required.
Enter your BTU load
Use a result from the BTU calculator, or your equipment's rated capacity if you already have one.
Or enter square footage directly
The calculator can estimate tonnage straight from room size if you haven't run a full BTU calculation.
Get your equipment size in tons
Results round to the standard sizes equipment is actually sold in.
What a 'Ton' Actually Means in HVAC
A ton of cooling capacity has nothing to do with equipment weight it's a unit borrowed from the era of ice-based refrigeration.
Converting BTU to Tons
The math is straightforward divide total BTU/hr load by 12,000 to get tonnage but equipment doesn't ship in fractional sizes beyond half-ton increments, so the calculator rounds to the nearest standard size (1.5, 2, 2.5, 3, 3.5, 4, or 5 ton for most residential equipment).
Why Rounding Direction Matters
When a BTU load falls between two standard sizes, rounding up slightly is usually the safer choice for cooling performance, while rounding down can leave a system working harder than it should on the hottest days. Oversizing significantly, though, causes its own problems short-cycling and poor humidity control so this isn't a "bigger is always better" decision either.
Tonnage and Refrigerant Charge
Larger tonnage systems carry proportionally more refrigerant charge, which matters when planning ahead for a future recovery job the recovery calculator on this site uses total system charge, which scales with equipment tonnage, to recommend the right cylinder size.
Related Calculators
Frequently Asked Questions
One ton equals 12,000 BTU per hour a standard conversion used across all residential and light-commercial HVAC equipment.
Most residential equipment ships in 1.5, 2, 2.5, 3, 3.5, 4, and 5-ton sizes, with half-ton increments being the norm.
Rounding up slightly is usually safer for cooling performance, but oversizing significantly can cause short-cycling and poor humidity control.
Yes larger tonnage systems carry proportionally more refrigerant charge, which is useful to know ahead of a future recovery job.
Need the Refrigerant to Match?
Every calculator links straight to the in-stock cylinder for that refrigerant.