Natural Gas Piping - Sizing vs. Capacity

Sizing natural gas pipes with pressures above 5 psi (35 kPa). Calculate pipe capacity based on pressure, pipe diameter, and pipe length using Steel Pipe Schedule 40.

Calculator

Inputs

Pressure (psig)

Pipe Diameter

Pipe Length (ft)

Fittings Factor

Results

Equivalent Pipe Length-- ft

Pipe Capacity-- MBH

Pipe Capacity (CFH)-- CFH

Heating Capacity-- BTU/h

Pressure (psig)	1/2 in	3/4 in	1 in	1 1/4 in	1 1/2 in	2 in	2 1/2 in	3 in	4 in	5 in
10	355	745	1400	2880	4310	8305	13240	23400	47730	86350
9.5	515	1080	2030	4160	6240	12020	19150	33860	69060	124940
9	350	730	1370	2815	4210	8120	12940	22880	46600	84420
8.1	475	995	1875	3850	5770	11100	17700	31300	63840	115500
8	300	630	1190	2440	3650	7040	11215	19830	40440	76170
7.2	440	910	1720	3530	5290	10190	16240	28710	58560	105940
7	290	615	1160	2380	3565	6865	10940	19345	39460	71390
6.3	395	830	1560	3210	4810	9260	14760	26090	53210	96260
6	245	515	970	1990	2990	5730	9140	16160	32950	59620
5.4	355	745	1400	2880	4310	8310	13245	23415	47760	86400
5	240	500	940	1935	2900	5580	8895	15730	32080	58030
4.5	315	660	1240	2540	3810	7340	11695	20680	42170	76300

Conversion Factors

1 Cubic Foot (CF) ≈ 1,000 BTUs
1 CFH ≈ 1 MBH (MBH = thousands of BTUs per hour)
1 MBH = 1,000 BTU/h (0.29 kW)
1 Btu/h = 0.293 W
1 psi = 6,894.8 Pa (N/m²)
1 in water = 248.8 N/m² = 0.0361 psi = 25.4 kg/m²
1 lb = 0.4536 kg
1 ft = 0.3048 m

Notes

Inlet upstream pressure must be more than 5 psig (35 kPa)
Fittings factor 1.2 - equivalent pipe length = pipe length + 20%
Capacity tables are for Steel Pipes Schedule 40
Natural gas nominal BTU/cf varies from about 900 to 1100 BTU/cf