About

Natural gas utilities bill in CCF (centum cubic feet), but energy content is measured in therms. A direct 1:1 assumption between CCF and therms is incorrect. The actual ratio depends on the gas heating value, which varies by source and region - typically 1,000 to 1,050 BTU/ft³. At the U.S. pipeline standard of 1,024 BTU/ft³, 1 CCF = 1.024 therms - not 1.0. That 2.4% difference compounds across billing cycles and large commercial accounts. This calculator applies the thermometric conversion factor f to your CCF reading, producing therms, BTU, and raw cubic feet. You can adjust the BTU-per-cubic-foot factor to match your utility's published heating value for precise reconciliation against invoices.

Formulas

The core conversion from CCF to therms relies on the heating value of natural gas per cubic foot. One CCF equals 100 cubic feet. One therm equals 100,000 BTU.

Therms = CCF × 100 × f100,000

Simplified:

Therms = CCF × f1,000

Where:

BTU_total = CCF × 100 × f

CCF = volume reading from meter in centum (hundred) cubic feet. f = heating value of gas in BTU/ft³, typically 1,000 - 1,050; default 1,024. Therms = energy output in therms (1 therm = 100,000 BTU). BTU_total = total British Thermal Units. Additional conversions: 1 BTU = 1,055.06 J. 1 therm = 105,505,585.26 J ≈ 29.3 kWh.

Reference Data

CCF	Cubic Feet	Therms (at 1,024 BTU/ft³)	BTU	MJ (approx)	kWh (approx)
1	100	1.024	102,400	108.0	30.0
5	500	5.120	512,000	540.2	150.1
10	1,000	10.240	1,024,000	1,080.3	300.1
25	2,500	25.600	2,560,000	2,700.8	750.3
50	5,000	51.200	5,120,000	5,401.6	1,500.6
75	7,500	76.800	7,680,000	8,102.4	2,250.9
100	10,000	102.400	10,240,000	10,803.2	3,001.2
150	15,000	153.600	15,360,000	16,204.8	4,501.8
200	20,000	204.800	20,480,000	21,606.4	6,002.3
300	30,000	307.200	30,720,000	32,409.6	9,003.5
500	50,000	512.000	51,200,000	54,016.0	15,005.8
750	75,000	768.000	76,800,000	81,024.0	22,508.8
1,000	100,000	1,024.000	102,400,000	108,032.0	30,011.7
2,500	250,000	2,560.000	256,000,000	270,080.0	75,029.3
5,000	500,000	5,120.000	512,000,000	540,160.0	150,058.6

Frequently Asked Questions

Because 1 CCF does not equal exactly 1 therm. The conversion depends on the heating value (BTU content) of the gas delivered to your area. At the common pipeline standard of 1,024 BTU per cubic foot, 1 CCF equals 1.024 therms. Your utility publishes their specific therm factor on your bill or tariff schedule. Enter that factor into this calculator's BTU/ft³ field for exact reconciliation.

Check your utility bill or contact your gas provider. In the U.S., pipeline-quality natural gas typically ranges from 1,000 to 1,050 BTU/ft³. The EIA national average is approximately 1,037 BTU/ft³. Some utilities use a fixed billing factor (e.g., 1.024 or 1.037 therms per CCF), which you can reverse-engineer: multiply the factor by 1,000 to get the BTU/ft³ value they assume.

Gas meters measure volume at the meter's conditions, not at standard temperature and pressure (STP: 60°F, 14.696 psia). Utilities apply a pressure-temperature correction factor to adjust readings to standard conditions before billing. If you are at high altitude (lower pressure) or extreme cold, the actual energy per measured cubic foot changes. This calculator assumes the CCF reading has already been corrected to standard conditions, which is the norm for residential billing.

No. CCF means 100 cubic feet (C = Roman numeral for 100). MCF (or Mcf) means 1,000 cubic feet (M = Roman numeral for 1,000). 1 MCF = 10 CCF. Commercial and industrial accounts often use MCF or MMBtu (million BTU), while residential meters typically read in CCF. Ensure you are reading the correct unit from your meter or bill before converting.

Not directly. This tool assumes natural gas composition. Propane has approximately 2,516 BTU per cubic foot - roughly 2.5× the heating value of natural gas. If you enter propane's BTU/ft³ value (2,516) into the BTU factor field, the math is technically correct, but propane is rarely metered in CCF. Propane is typically sold by the gallon (91,500 BTU/gal). Use a propane-specific converter for accuracy.

Utilities apply several adjustments beyond the basic CCF-to-therm conversion: pressure correction factors, temperature correction factors, meter calibration adjustments, and sometimes a "gas quality factor" specific to their supply. Some utilities also round to the nearest whole therm. This calculator provides the thermodynamic conversion; billing adjustments are utility-specific. Compare your bill's stated therm factor against the one used here.