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Ton-Hours and Cooling Energy Calculator

A ton-hour is one ton of cooling for one hour — 12,000 BTU of heat removed. Convert loads to ton-hours and then to the electricity they cost.

Method reviewed October 26, 2026. Version 1.0.0. How it works

Your inputs

Unit system

Electric input per ton of cooling. Include pumps, fans and towers if you want whole-plant energy. kW/ton = 12 ÷ EER.

US residential average: 18.31¢/kWh (EIA, July 2026). Commercial rates differ — use your bill.

Result

Cooling delivered
500ton-h
Electricity used
500kWh
Electricity cost
$91.55

500 ton-hours of cooling uses about 500 kWh at 1 kW/ton, costing $91.55.

Cooling delivered
6,000,000BTU
kW per ton used
1
Show the working
  1. Ton-hours = tons × hours
    50 × 10 = 500 ton-h (6,000,000 BTU)
  2. Electricity = ton-hours × kW per ton
    500 × 1 = 500 kWh
  3. Cost = kWh × price
    500 × $0.1831 = $91.55

The conversions

  • Ton-hours = average tons × hours, or total BTU ÷ 12,000
  • kWh = ton-hours × kW per ton
  • kW per ton = 12 ÷ EER
  • Cost = kWh × electricity price

Ton-hours are how chilled-water plants, thermal storage and BTU meters report cooling delivered. kW per ton is the usual efficiency figure for chillers and plants.

Getting a good kW per ton

Use the average efficiency over the period, not the best-case rating. Include pumps, tower fans and air-handler fans if you want the whole plant’s electricity rather than just the compressor’s. Demand charges and fixed charges are separate — use the Demand Charge Calculator for the peak-kW part of a commercial bill.

Worked example

These are the example values the calculator opens with, and the result the engine calculates for them.

Inputs

Cooling delivered from
Average load (tons) and hours
Average cooling load
50 tons
Hours at that load
10 h
Efficiency entered as
kW per ton (whole plant or unit)
kW per ton
1
Electricity price
0.183 $/kWh

Result

Cooling delivered
500 ton-h
Electricity used
500 kWh
Electricity cost
$91.55
Cooling delivered
6,000,000 BTU
kW per ton used
1

500 ton-hours of cooling uses about 500 kWh at 1 kW/ton, costing $91.55.

Assumptions

  • 1 ton-hour = 12,000 BTU of heat removed.
  • Electricity = ton-hours × kW per ton; kW per ton = 12 ÷ EER.

Limitations

  • Efficiency changes with load and weather; an average kW per ton for the period gives the best estimate.
  • Excludes demand charges and fixed charges.

Frequently asked questions

How many BTU is a ton-hour?

12,000 BTU — one ton of refrigeration (12,000 BTU/h) for one hour.

Is a ton-hour the same as a kWh?

No. A ton-hour measures heat removed; a kWh measures electricity used. Their ratio is the kW-per-ton efficiency.

What is a good kW per ton?

Lower is better. It depends on the equipment type and conditions, so compare with the manufacturer’s ratings at similar conditions.

Sources

  1. NIST Guide to the SI (SP 811), Appendix B.9 — conversion factors — National Institute of Standards and Technology. 1 ton of refrigeration = 12,000 BTU/h; 1 BTU/h = 0.2930711 W; 1 atm = 101.325 kPa.
  2. 2023 Central Air Conditioner Standards — FAQ — U.S. DOE, Office of Energy Efficiency & Renewable Energy. Regional SEER2 / EER2 / HSPF2 minimum efficiencies effective 2023.
  3. Electric Power Monthly, Table 5.6.A — average price to ultimate customers — U.S. Energy Information Administration. U.S. residential electricity price, 18.31 ¢/kWh in July 2026.

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