Natural Gas Pipe Sizing Chart — Schedule 40

Capacity in cubic feet of natural gas per hour for Schedule 40 metallic pipe at inlet pressures under 2 psi and 0.60 specific gravity — the two low-pressure tables used with the longest-length method, at 0.3 and 0.5 inch water column pressure drop. Values per IFGC Tables 402.4(1) and 402.4(2) (2021 edition; unchanged IFGC 2015–2024), identical cell-for-cell to NFPA 54 Tables 6.2.1(a) and 6.2.1(b). Confirm which pressure drop your jurisdiction or utility sizes to.

0.3 in. w.c. pressure drop — natural gas, Sch 40, < 2 psi

IFGC 402.4(1)

Maximum capacity in cubic feet of gas per hour by pipe size and length of run. Natural gas, 0.60 specific gravity, inlet pressure less than 2 psi, 0.3 in. w.c. pressure drop — per IFGC Table 402.4(1) (2021 edition), identical to NFPA 54 Table 6.2.1(a). A dash means the combination cannot deliver even 10 CFH.
Length (ft)	1/2″ (0.622″ ID)	3/4″ (0.824″ ID)	1″ (1.049″ ID)	1-1/4″ (1.380″ ID)	1-1/2″ (1.610″ ID)	2″ (2.067″ ID)	2-1/2″ (2.469″ ID)	3″ (3.068″ ID)	4″ (4.026″ ID)	5″ (5.047″ ID)	6″ (6.065″ ID)	8″ (7.981″ ID)	10″ (10.020″ ID)	12″ (11.938″ ID)
10	131	273	514	1,060	1,580	3,050	4,860	8,580	17,500	31,700	51,300	105,000	191,000	303,000
20	90	188	353	726	1,090	2,090	3,340	5,900	12,000	21,800	35,300	72,400	132,000	208,000
30	72	151	284	583	873	1,680	2,680	4,740	9,660	17,500	28,300	58,200	106,000	167,000
40	62	129	243	499	747	1,440	2,290	4,050	8,270	15,000	24,200	49,800	90,400	143,000
50	55	114	215	442	662	1,280	2,030	3,590	7,330	13,300	21,500	44,100	80,100	127,000
60	50	104	195	400	600	1,160	1,840	3,260	6,640	12,000	19,500	40,000	72,600	115,000
70	46	95	179	368	552	1,060	1,690	3,000	6,110	11,100	17,900	36,800	66,800	106,000
80	42	89	167	343	514	989	1,580	2,790	5,680	10,300	16,700	34,200	62,100	98,400
90	40	83	157	322	482	928	1,480	2,610	5,330	9,650	15,600	32,100	58,300	92,300
100	38	79	148	304	455	877	1,400	2,470	5,040	9,110	14,800	30,300	55,100	87,200
125	33	70	131	269	403	777	1,240	2,190	4,460	8,080	13,100	26,900	48,800	77,300
150	30	63	119	244	366	704	1,120	1,980	4,050	7,320	11,900	24,300	44,200	70,000
175	28	58	109	224	336	648	1,030	1,820	3,720	6,730	10,900	22,400	40,700	64,400
200	26	54	102	209	313	602	960	1,700	3,460	6,260	10,100	20,800	37,900	59,900
250	23	48	90	185	277	534	851	1,500	3,070	5,550	8,990	18,500	33,500	53,100
300	21	43	82	168	251	484	771	1,360	2,780	5,030	8,150	16,700	30,400	48,100
350	19	40	75	154	231	445	709	1,250	2,560	4,630	7,490	15,400	28,000	44,300
400	18	37	70	143	215	414	660	1,170	2,380	4,310	6,970	14,300	26,000	41,200
450	17	35	66	135	202	389	619	1,090	2,230	4,040	6,540	13,400	24,400	38,600
500	16	33	62	127	191	367	585	1,030	2,110	3,820	6,180	12,700	23,100	36,500
550	15	31	59	121	181	349	556	982	2,000	3,620	5,870	12,100	21,900	34,700
600	14	30	56	115	173	333	530	937	1,910	3,460	5,600	11,500	20,900	33,100
650	14	29	54	110	165	318	508	897	1,830	3,310	5,360	11,000	20,000	31,700
700	13	27	52	106	159	306	488	862	1,760	3,180	5,150	10,600	19,200	30,400
750	13	26	50	102	153	295	470	830	1,690	3,060	4,960	10,200	18,500	29,300
800	12	26	48	99	148	285	454	802	1,640	2,960	4,790	9,840	17,900	28,300
850	12	25	46	95	143	275	439	776	1,580	2,860	4,640	9,530	17,300	27,400
900	11	24	45	93	139	267	426	752	1,530	2,780	4,500	9,240	16,800	26,600
950	11	23	44	90	135	259	413	731	1,490	2,700	4,370	8,970	16,300	25,800
1,000	11	23	43	87	131	252	402	711	1,450	2,620	4,250	8,720	15,800	25,100
1,100	10	21	40	83	124	240	382	675	1,380	2,490	4,030	8,290	15,100	23,800
1,200	—	20	39	79	119	229	364	644	1,310	2,380	3,850	7,910	14,400	22,700
1,300	—	20	37	76	114	219	349	617	1,260	2,280	3,680	7,570	13,700	21,800
1,400	—	19	35	73	109	210	335	592	1,210	2,190	3,540	7,270	13,200	20,900
1,500	—	18	34	70	105	203	323	571	1,160	2,110	3,410	7,010	12,700	20,100
1,600	—	18	33	68	102	196	312	551	1,120	2,030	3,290	6,770	12,300	19,500
1,700	—	17	32	66	98	189	302	533	1,090	1,970	3,190	6,550	11,900	18,800
1,800	—	16	31	64	95	184	293	517	1,050	1,910	3,090	6,350	11,500	18,300
1,900	—	16	30	62	93	178	284	502	1,020	1,850	3,000	6,170	11,200	17,700
2,000	—	16	29	60	90	173	276	488	1,000	1,800	2,920	6,000	10,900	17,200

All capacities are rounded to three significant digits in the code itself. Multiply CFH by your local heating value (≈1,000 BTU/cf typical) for BTU/hr.

0.5 in. w.c. pressure drop — natural gas, Sch 40, < 2 psi

IFGC 402.4(2)

Maximum capacity in cubic feet of gas per hour by pipe size and length of run. Natural gas, 0.60 specific gravity, inlet pressure less than 2 psi, 0.5 in. w.c. pressure drop — per IFGC Table 402.4(2) (2021 edition), identical to NFPA 54 Table 6.2.1(b). A dash means the combination cannot deliver even 10 CFH.
Length (ft)	1/2″ (0.622″ ID)	3/4″ (0.824″ ID)	1″ (1.049″ ID)	1-1/4″ (1.380″ ID)	1-1/2″ (1.610″ ID)	2″ (2.067″ ID)	2-1/2″ (2.469″ ID)	3″ (3.068″ ID)	4″ (4.026″ ID)	5″ (5.047″ ID)	6″ (6.065″ ID)	8″ (7.981″ ID)	10″ (10.020″ ID)	12″ (11.938″ ID)
10	172	360	678	1,390	2,090	4,020	6,400	11,300	23,100	41,800	67,600	139,000	252,000	399,000
20	118	247	466	957	1,430	2,760	4,400	7,780	15,900	28,700	46,500	95,500	173,000	275,000
30	95	199	374	768	1,150	2,220	3,530	6,250	12,700	23,000	37,300	76,700	139,000	220,000
40	81	170	320	657	985	1,900	3,020	5,350	10,900	19,700	31,900	65,600	119,000	189,000
50	72	151	284	583	873	1,680	2,680	4,740	9,660	17,500	28,300	58,200	106,000	167,000
60	65	137	257	528	791	1,520	2,430	4,290	8,760	15,800	25,600	52,700	95,700	152,000
70	60	126	237	486	728	1,400	2,230	3,950	8,050	14,600	23,600	48,500	88,100	139,000
80	56	117	220	452	677	1,300	2,080	3,670	7,490	13,600	22,000	45,100	81,900	130,000
90	52	110	207	424	635	1,220	1,950	3,450	7,030	12,700	20,600	42,300	76,900	122,000
100	50	104	195	400	600	1,160	1,840	3,260	6,640	12,000	19,500	40,000	72,600	115,000
125	44	92	173	355	532	1,020	1,630	2,890	5,890	10,600	17,200	35,400	64,300	102,000
150	40	83	157	322	482	928	1,480	2,610	5,330	9,650	15,600	32,100	58,300	92,300
175	37	77	144	296	443	854	1,360	2,410	4,910	8,880	14,400	29,500	53,600	84,900
200	34	71	134	275	412	794	1,270	2,240	4,560	8,260	13,400	27,500	49,900	79,000
250	30	63	119	244	366	704	1,120	1,980	4,050	7,320	11,900	24,300	44,200	70,000
300	27	57	108	221	331	638	1,020	1,800	3,670	6,630	10,700	22,100	40,100	63,400
350	25	53	99	203	305	587	935	1,650	3,370	6,100	9,880	20,300	36,900	58,400
400	23	49	92	189	283	546	870	1,540	3,140	5,680	9,190	18,900	34,300	54,300
450	22	46	86	177	266	512	816	1,440	2,940	5,330	8,620	17,700	32,200	50,900
500	21	43	82	168	251	484	771	1,360	2,780	5,030	8,150	16,700	30,400	48,100
550	20	41	78	159	239	459	732	1,290	2,640	4,780	7,740	15,900	28,900	45,700
600	19	39	74	152	228	438	699	1,240	2,520	4,560	7,380	15,200	27,500	43,600
650	18	38	71	145	218	420	669	1,180	2,410	4,360	7,070	14,500	26,400	41,800
700	17	36	68	140	209	403	643	1,140	2,320	4,190	6,790	14,000	25,300	40,100
750	17	35	66	135	202	389	619	1,090	2,230	4,040	6,540	13,400	24,400	38,600
800	16	34	63	130	195	375	598	1,060	2,160	3,900	6,320	13,000	23,600	37,300
850	16	33	61	126	189	363	579	1,020	2,090	3,780	6,110	12,600	22,800	36,100
900	15	32	59	122	183	352	561	992	2,020	3,660	5,930	12,200	22,100	35,000
950	15	31	58	118	178	342	545	963	1,960	3,550	5,760	11,800	21,500	34,000
1,000	14	30	56	115	173	333	530	937	1,910	3,460	5,600	11,500	20,900	33,100
1,100	14	28	53	109	164	316	503	890	1,810	3,280	5,320	10,900	19,800	31,400
1,200	13	27	51	104	156	301	480	849	1,730	3,130	5,070	10,400	18,900	30,000
1,300	12	26	49	100	150	289	460	813	1,660	3,000	4,860	9,980	18,100	28,700
1,400	12	25	47	96	144	277	442	781	1,590	2,880	4,670	9,590	17,400	27,600
1,500	11	24	45	93	139	267	426	752	1,530	2,780	4,500	9,240	16,800	26,600
1,600	11	23	44	89	134	258	411	727	1,480	2,680	4,340	8,920	16,200	25,600
1,700	11	22	42	86	130	250	398	703	1,430	2,590	4,200	8,630	15,700	24,800
1,800	10	22	41	84	126	242	386	682	1,390	2,520	4,070	8,370	15,200	24,100
1,900	10	21	40	81	122	235	375	662	1,350	2,440	3,960	8,130	14,800	23,400
2,000	—	20	39	79	119	229	364	644	1,310	2,380	3,850	7,910	14,400	22,700

The 0.5 in. w.c. table allows more pressure loss, so every cell is at or above its 0.3 in. w.c. counterpart. Which drop governs is a jurisdiction / utility policy call.

How the longest-length method works

Total the BTU/hr input of every connected appliance and convert to CFH using your local heating value. Measure the developed length of pipe from the point of delivery (the meter) to the most remote appliance outlet, and round UP to the next table row. That one row then sizes the entire system: for each segment, read across to find the smallest pipe size whose capacity covers the total load flowing through that segment. Runs with four or more fittings should carry an equivalent-length allowance per the code text before picking the row.

What these tables do not cover

These are the low-pressure Schedule 40 metallic-pipe tables only. Different tables govern CSST (which sizes by each manufacturer's EHD tables), polyethylene yard piping, 2 psi and higher-pressure systems, and LP/propane — never read propane loads from a natural-gas table. Undiluted propane has both a different heating value and a different specific gravity. Altitude also derates appliance input. As always, your jurisdiction may amend the model code — confirm the enforced edition and the required pressure drop before finalizing a design.

For pressure-loss work outside these table conditions, the pressure loss calculator covers general piping runs.

Common questions

What size gas pipe do I need for a 100,000 BTU appliance?

First convert to cubic feet per hour: at a typical heating value of about 1,000 BTU per cubic foot, 100,000 BTU/hr is roughly 100 CFH. Then read the row for your system's longest run: at 50 ft on the 0.5 in. w.c. table, 3/4" carries 151 CFH — enough; at 0.3 in. w.c. it carries 114 CFH — still enough, but a 90 ft run drops 3/4" to 83 CFH and pushes you to 1". The whole system's longest run, not the appliance's own branch length, picks the row.

How does the longest-length method work?

Measure the developed length from the meter (point of delivery) to the farthest appliance outlet, round up to the next table row, and size EVERY segment of the system from that one row — each segment for the total BTU load it carries downstream. It is deliberately conservative and is the method the capacity tables assume.

Should I use the 0.3 or 0.5 inch water column table?

That is a design-policy choice, not a free pick: the allowable pressure drop depends on the supply pressure and what the appliances need, and many jurisdictions or gas utilities specify which drop to size to. The 0.3 table is the more conservative of the two. When in doubt, ask the AHJ or the serving utility.

How do I convert CFH to BTU per hour?

Multiply by your gas's heating value — roughly 1,000 BTU per cubic foot for typical utility natural gas, but it varies by supplier (about 1,000 to 1,100). The code tables are printed in CFH precisely because the BTU content of gas is not constant; your utility can tell you the local value.

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