Watt to Ton Converter
Convert between watts, tons of refrigeration, and BTU/hr for air conditioning sizing. Factor in SEER/EER ratings for actual electrical consumption.
Convert Watts ↔ Tons
Enter cooling capacity in watts, tons, or BTU/hr to convert between units.
What is a Ton of Refrigeration?
One ton of refrigeration (TR) equals the cooling capacity of melting one short ton (2,000 lbs) of ice in 24 hours. This equals 12,000 BTU/hr or 3,517 watts of cooling power. Air conditioners are rated in tons to indicate their cooling capacity.
AC Tonnage Sizing Guide
| Room/Area Size | Recommended Tonnage | Cooling (BTU/hr) | Cooling (Watts) |
|---|---|---|---|
| 100-200 sqft | 0.5 Ton | 6,000 | 1,758 W |
| 200-350 sqft | 1.0 Ton | 12,000 | 3,517 W |
| 350-550 sqft | 1.5 Ton | 18,000 | 5,275 W |
| 550-800 sqft | 2.0 Ton | 24,000 | 7,034 W |
| 800-1,100 sqft | 2.5 Ton | 30,000 | 8,792 W |
| 1,100-1,500 sqft | 3.0 Ton | 36,000 | 10,551 W |
| 1,500-2,000 sqft | 4.0 Ton | 48,000 | 14,068 W |
| 2,000-2,500 sqft | 5.0 Ton | 60,000 | 17,585 W |
Understanding SEER Ratings
SEER (Seasonal Energy Efficiency Ratio) measures how efficiently an AC converts electricity into cooling over a typical cooling season. Higher SEER = less electricity used. SEER = Total BTU cooling output ÷ Total Wh electrical input.
- SEER 13-14: Minimum efficiency (older units)
- SEER 16-18: High efficiency (good savings)
- SEER 20-25: Ultra-high efficiency (premium models)
- SEER 25+: Top-tier inverter units
A 3-ton AC (36,000 BTU/hr) at SEER 14 uses 2.57 kW; at SEER 20 it uses only 1.80 kW — a 30% reduction in electricity consumption.
Frequently Asked Questions About AC Tonnage & Watts
How many watts does a 1-ton AC use?
A 1-ton AC provides 3,517 watts of cooling but the electrical consumption depends on SEER rating. At SEER 14: ~857W electrical input. At SEER 20: ~600W. The 3,517W refers to cooling capacity, not electricity consumed.
How do I convert BTU to watts?
Divide BTU/hr by 3.412 to get watts: Watts = BTU/hr ÷ 3.412. For example, 12,000 BTU/hr ÷ 3.412 = 3,517 watts of cooling capacity.
What size AC do I need for my room?
A general rule is 20 BTU per square foot of living space. A 300 sqft room needs ~6,000 BTU (0.5 ton). A 1,000 sqft area needs ~20,000 BTU (1.67 tons). Adjust upward for high ceilings, sunny rooms, kitchens, or hot climates.
What is the difference between EER and SEER?
EER is measured at a single outdoor temperature (95°F), while SEER averages over an entire cooling season with temperatures from 65–104°F. SEER better represents real-world annual performance. EER is useful for comparing peak cooling efficiency.
How much electricity does central AC use?
A typical 3-ton central AC uses 2,000-3,500 watts of electricity when running. At SEER 14, a 3-ton unit draws about 2,571W. Running 8 hours/day at $0.12/kWh costs approximately $2.47/day or $74/month.