Gas carrying capacities in house piping (cubic feet per hour) for low pressure gas with specific gravity 0.6 and a pressure drop of 0.3 inches of water over the entire pipe length.
Pipe Length(ft)	1/2 in.(ft³/h)	3/4 in.(ft³/h)	1 in.(ft³/h)	1¼ in.(ft³/h)	1½ in.(ft³/h)	2 in.(ft³/h)	3 in.(ft³/h)	4 in.(ft³/h)	6 in.(ft³/h)	8 in.(ft³/h)
15	76	172	345	750	1220	2480	6500	13880	38700	79000
30	52	120	241	535	850	1780	4700	9700	27370	55850
45	43	99	199	435	700	1475	3900	7900	23350	45600
60	38	86	173	380	610	1290	3450	6800	19330	39500
75	—	77	155	345	545	1120	3000	6000	17310	35300
90	—	70	141	310	490	1000	2700	5500	15800	32250
105	—	65	131	285	450	920	2450	5100	14620	29850
120	—	—	120	270	420	860	2300	4800	13680	27920
150	—	—	109	242	380	780	2090	4350	12240	25000
180	—	—	100	225	350	720	1950	4000	11160	22800
210	—	—	—	205	320	660	1780	3700	10330	21100
240	—	—	—	190	300	620	1680	3490	9600	19740
270	—	—	—	178	285	580	1580	3250	9000	18660
300	—	—	—	170	270	545	1490	3000	8500	17660
450	—	—	—	—	140	226	450	1230	7000	14420
600	—	—	—	—	119	192	390	1030	6000	12480

Source: engineeringtoolbox.com

Sizing Notes

The table applies to low-pressure gas systems with *specific gravity 0.6 (natural gas).
Pressure drop is assumed as 0.3 inches of water column over the entire pipe length.
Pipe lengths and capacities are based on standard steel or copper tubing.
For multi-apartment buildings, use the "Sizing Low Pressure Gas Service Pipes" guideline to determine the required pipe size for connecting multiple units through a common service pipe.
Capacities decrease significantly with longer pipe runs due to friction losses.

Gas Pipes Capacity