Ton of Refrigeration to Kilowatt Converter

How many tons of AC do I need?

Basic calculation: Square footage ÷ 400-600 = tons needed

More accurate method:

1. Calculate BTU/h needed (sq ft × 20-25 BTU/h)
2. Divide by 12,000 to get tons

Example (1,800 sq ft home):

• BTU/h needed: 1,800 × 22 = 39,600 BTU/h
• Tons needed: 39,600 ÷ 12,000 = 3.3 tons
• Choose: 3 ton or 3.5 ton system

Factors affecting sizing:

• Climate zone (hot = more, moderate = less)
• Insulation quality
• Window area and orientation
• Ceiling height
• Number of occupants
• Heat-generating appliances

[AC sizing calculator]

How do I convert tons to BTU/h or kW?

Formulas:

• BTU/h = Tons × 12,000
• kW = Tons × 3.517

Examples:

• 2 tons = 24,000 BTU/h = 7.03 kW
• 3 tons = 36,000 BTU/h = 10.55 kW
• 4 tons = 48,000 BTU/h = 14.07 kW
• 5 tons = 60,000 BTU/h = 17.58 kW

Reverse:

• BTU/h ÷ 12,000 = Tons
• kW ÷ 3.517 = Tons

Tons to BTU/h converter → Tons to kW converter →

Why is it called a "ton" of refrigeration?

Historical origin: In the 1800s, ice production was measured by tons of ice produced.

The definition: 1 ton of refrigeration = cooling power needed to freeze 1 ton (2,000 pounds) of water at 32°F into ice in 24 hours.

The math:

• Latent heat of ice: 144 BTU per pound
• 2,000 lbs × 144 BTU/lb = 288,000 BTU in 24 hours
• 288,000 BTU ÷ 24 hours = 12,000 BTU/h

Modern usage: The unit stuck even though we no longer use ice for cooling. It's purely a power measurement, NOT a weight!

What size AC for 2000 sq ft?

Typical: 3-4 tons (36,000-48,000 BTU/h)

Calculation (using 20 BTU/h per sq ft):

• 2,000 sq ft × 20 = 40,000 BTU/h
• 40,000 ÷ 12,000 = 3.33 tons
• Result: 3-ton or 3.5-ton system

Climate adjustments:

• Hot climate (Arizona, Florida): 4 tons (higher load)
• Moderate climate: 3-3.5 tons
• Cool climate (Northern states): 2.5-3 tons

Other factors:

• Well-insulated home: Can use smaller (3 tons)
• Poor insulation, lots of windows: Need larger (4 tons)
• High ceilings: Add 10-20%
• Multiple stories: May need multiple smaller units

Is bigger better for AC tonnage?

NO! Oversizing causes problems:

Issues with oversized AC:

• Short cycling: Turns on/off frequently, wears out faster
• Poor dehumidification: Doesn't run long enough to remove humidity
• Hot/cold spots: Uneven cooling
• Higher energy bills: Inefficient operation
• Shorter lifespan: More wear and tear

Ideal sizing: AC should run 15-20 minutes per cycle, cycling 2-3 times per hour on hot days

Example:

• 1,500 sq ft home needs 2.5-3 tons
• Installing 5 tons would be wasteful and problematic
• Better to size correctly or slightly undersize than oversize