How many BTU are in a ton of cooling?

One ton equals 12,000 BTU/h, the heat needed to melt one ton of ice in 24 hours.

How is sensible capacity calculated?

Sensible BTU/h = 1.08 × CFM × temperature split, valid at standard air density near sea level.

What is a rule of thumb for sizing?

Roughly 400–600 ft² per ton in a typical home, but only a Manual J load calculation gives a defensible size.

AC Tonnage Calculator — BTU & Sq Ft to Tons

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Formula

Tons = BTU/hr ÷ 12,000 · Rough: sqft × zone factor × construction

Square-footage sizing is a rough starting point. For final sizing always run Manual J with actual window area, orientation, infiltration, and internal gains.

Input

Conditioned area

ft²

Climate zone

Construction

Cooling load

50,400BTU/hr

50.4 kBTU/hr · 14.77 kW

Nominal size

4.20tons

Round to nearest 0.5 ton for equipment selection

Reference: 1 ton = 12,000 BTU/hr = 3.517 kW. Typical residential: 400–500 sqft/ton depending on climate and envelope.

How to use this calculator

Convert BTU/h or measured airflow and enthalpy change into tons of cooling.

Enter cooling capacity in BTU/h, or airflow with the temperature and humidity change.
Select the calculation basis, sensible only or total.
Read the capacity in tons and kW.
Compare with the equipment's rated capacity at the current conditions.

Frequently asked questions

How many BTU are in a ton of cooling?: One ton equals 12,000 BTU/h, the heat needed to melt one ton of ice in 24 hours.
How is sensible capacity calculated?: Sensible BTU/h = 1.08 × CFM × temperature split, valid at standard air density near sea level.
What is a rule of thumb for sizing?: Roughly 400–600 ft² per ton in a typical home, but only a Manual J load calculation gives a defensible size.