BTU to Cubic Feet per Hour (CFH) Conversion Calculator
Use this tool to convert BTU/h (British Thermal Units per hour) into CFH (Cubic Feet per Hour) of natural gas. Perfect for HVAC engineers, gas technicians, and energy specialists.
Understanding the BTU to CFH Conversion
What is BTU/h?
BTU/h, or British Thermal Units per hour, is a unit of power that indicates the rate of energy usage. One BTU is the amount of energy required to raise the temperature of one pound of water by one degree Fahrenheit. In heating, cooking, and industrial energy systems, BTU/h is a standard measurement of energy flow.
What is CFH (Cubic Feet per Hour)?
CFH is a volumetric flow rate unit used primarily in gas-related applications. It indicates how many cubic feet of gas are consumed or delivered per hour. In the U.S., CFH is often used to rate natural gas usage in residential and commercial appliances, such as furnaces, boilers, and stoves.
Why Convert BTU/h to CFH?
Gas appliances are typically rated in BTU/h, while gas supply systems are rated in CFH. Converting between the two allows engineers, architects, and contractors to size gas lines, regulators, and meters correctly.
Conversion Formula
The conversion from BTU/h to CFH depends on the energy content (heating value) of natural gas. The typical value used in the U.S. is:
- 1 cubic foot of natural gas ≈ 1,020 BTU (higher heating value)
Therefore, the formula becomes:
- CFH = BTU/h ÷ 1,020
Practical Examples
| Appliance | BTU/h | CFH |
|---|---|---|
| Residential Gas Stove (4 burners) | 40,000 | 39.22 |
| Water Heater (40-gallon) | 36,000 | 35.29 |
| Gas Furnace (medium home) | 100,000 | 98.04 |
| Commercial Boiler | 500,000 | 490.20 |
Frequently Asked Questions
Is 1,020 BTU per cubic foot always accurate?
No. The actual energy content of natural gas can vary between 950–1,100 BTU per cubic foot depending on the source, altitude, and composition. Always confirm with your gas utility for exact local values.
What if my gas source has a different heating value?
You can adjust the formula to fit your gas's specific heating value. For example, if your gas contains 1,050 BTU per cubic foot, then CFH = BTU/h ÷ 1,050. You can also ask your utility company for the latest specs.
How is this conversion used in gas pipe sizing?
When sizing gas piping systems, knowing the required CFH helps determine the correct pipe diameter and material. Undersized pipes lead to pressure drops and poor appliance performance.
Can this calculator be used for propane or LP gas?
This tool is designed for natural gas. Propane has a different energy content (~2,516 BTU per cubic foot), so a separate calculator would be more accurate for LP gas systems.
What safety standards apply when sizing by CFH?
Always follow your local building codes and refer to ANSI standards (like ANSI Z223.1/NFPA 54) when designing fuel gas systems. This calculator is meant as a quick reference and not a substitute for engineering review.