What the result means
US equipment is rated in Btu/h or tons, while electric heat, heat pumps from other markets and many spec sheets use kilowatts. This converter keeps all three in view so you can compare equipment on the same basis.
Remember that output kW (thermal capacity) is not the same as the electrical input kW on the nameplate, except for resistance heat where they are equal.
How it's calculated
- kW = Btu/h ÷ 3,412.142
- Tons = Btu/h ÷ 12,000
- Btu/h = kW × 3,412.142 = tons × 12,000
Worked example
A 3-ton condenser rated 36,000 Btu/h.
- kW = 36,000 ÷ 3,412.142 = 10.55 kW
- Tons = 36,000 ÷ 12,000 = 3
A 36,000 Btu/h unit delivers about 10.55 kW of cooling.
Reference table
The values below are computed from the same calculator functions used above. They let you compare common sizes and operating points without replacing the interactive calculation or its assumptions.
| Btu/h | kW | Refrigeration tons |
|---|---|---|
| 6,000 | 1.76 | 0.50 |
| 12,000 | 3.52 | 1.00 |
| 18,000 | 5.28 | 1.50 |
| 24,000 | 7.03 | 2.00 |
| 30,000 | 8.79 | 2.50 |
| 36,000 | 10.55 | 3.00 |
| 42,000 | 12.31 | 3.50 |
| 48,000 | 14.07 | 4.00 |
| 54,000 | 15.83 | 4.50 |
| 60,000 | 17.58 | 5.00 |
Reference values are examples based on the stated assumptions. Verify manufacturer data, conductor ampacity and local requirements before using a result.
Sources and assumptions
The listed formulas use the assumptions shown in the worked example. Calculator formulas are published with their units so a technician can check a result instead of treating it as a black box.
Last reviewed . Spot an error? Email support@tiermenu.com.
FAQ
Where does 12,000 Btu/h per ton come from?
It's the heat needed to melt one ton of ice over 24 hours, the historical basis for cooling ratings.
Is a 10 kW heat strip the same as 34,121 Btu/h?
At full rated voltage, yes. At lower voltage a resistance heater puts out less, in proportion to the square of voltage.
Why do nominal tons differ from actual capacity?
Nominal size is a label. Actual capacity depends on conditions, airflow and the matched indoor coil. Use AHRI or manufacturer data.
Should I use Btu or Btu/h?
Capacity is a rate, so Btu/h is correct. In the field people often say "Btu" meaning Btu/h.
Using a reference result in the field
A calculator is most useful when the inputs match the job being checked. Confirm whether a value is nominal or measured, and whether readings were taken at design or actual operating conditions. The unit label beside the result is part of the result; do not carry a number into another calculation without checking its units.
Reference rows are provided for comparison, not as universal design limits. They use the values and conditions stated with each table. Elevation, air temperature, equipment and installation details can change a field result. Where the page calls out a code check, equipment rating or manufacturer table, that check remains part of the job.
Use the interactive inputs for the exact conditions at hand, then review the displayed formula and assumptions. If a value looks unexpected, change one input at a time and compare it with a known point in the reference table. Keep the measured readings and job-specific notes with the work record so another technician can understand how the result was obtained.
TierMenu provides these free calculators without an email gate. The results stay in this browser unless you choose to copy a shareable URL or print the page. A shared URL includes the calculator inputs in its query string; do not put personal or sensitive information in calculator fields.