Schedule 40 vs 80 Pipe Size Chart

What is a steel pipe?

Before we can explain how pipes are measured and categorized, it’s important to understand what makes a pipe a pipe (vs. a tube). A steel pipe is a cylindrical piece of steel with a hollow inside that’s generally used to carry gas or liquid from one location to another. They’re also the most utilized item produced by the steel industry.Steel with a hollow section whose length is much greater than its diameter or circumference. According to the cross-sectional shape, it is divided into round, square, rectangular and special-shaped steel pipes; according to the material, it is divided into carbon structural steel pipes, low alloy structural steel pipes, alloy steel pipes and composite steel pipes; according to the purpose, it is divided into steel pipes for pipelines, engineering structures, thermal equipment, petrochemical industry, machinery manufacturing, geological drilling, high-pressure equipment, etc.; according to the production process, it is divided into seamless steel pipes and welded steel pipes, among which seamless steel pipes are divided into hot-rolled and cold-rolled (drawn) types, and welded steel pipes are divided into straight seam welded steel pipes and spiral seam welded steel pipes.

Schedule 40 vs Schedule 80 Dimensional Standards

Schedule 40 is a widely used standard for pipe wall thickness in North America and internationally, based primarily on ASME/ANSI B36.10 (for steel pipe) or ASTM standards (for PVC/plastic pipe). It features a fixed outside diameter (OD) with wall thickness increasing alongside the nominal pipe size (NPS); it is suitable for low-to-medium pressure fluid transport and structural support applications.

The Schedule 80 dimensional standard adheres to specifications set by the American National Standards Institute (ANSI) and the American Society of Mechanical Engineers (ASME)—specifically ASME B36.10M for steel pipe—as well as ASTM standards for PVC and other plastic pipes. Its defining characteristic is a constant outside diameter combined with increased wall thickness (greater than that of Schedule 40) to enhance pressure-bearing capacity.

The pipe schedule formula:

Schedule 40 vs 80 Pipe Size Chart

Schedule 40 Steel Pipe Dimensions

Nominal size [inches]	Outside diameter [inches]	Outside diameter [mm]	Wall thickness [inches]	Wall thickness [mm]	Weight [lb/ft]	Weight [kg/m]
1/8	0.405	10.3	0.068	1.73	0.24	0.37
1/4	0.54	13.7	0.088	2.24	0.42	0.84
1/2	0.84	21.3	0.109	2.77	0.85	1.27
3/4	1.05	26.7	0.113	2.87	1.13	1.69
1	1.315	33.4	0.133	3.38	1.68	2.5
1.25	1.66	42.2	0.14	3.56	2.27	3.39
1.5	1.9	48.3	0.145	3.68	2.72	4.05
2	2.375	60.3	0.154	3.91	3.65	5.44
2.5	2.875	73	0.203	5.16	5.79	8.63
3	3.5	88.9	0.216	5.49	7.58	11.29
3.5	4	101.6	0.226	5.74	9.11	13.57
4	4.5	114.3	0.237	6.02	10.79	16.07
5	5.563	141.3	0.258	6.55	14.62	21.77
6	6.625	168.3	0.28	7.11	18.97	28.26
8	8.625	219.1	0.322	8.18	28.55	42.55
10	10.75	273	0.365	9.27	40.48	60.31
12	12.75	323.8	0.406	10.31	53.52	79.73
14	14	355.6	0.375	11.13	54.57	94.55
16	16	406.4	0.5	12.7	82.77	123.3
18	18	457	0.562	14.27	104.67	155.8
20	20	508	0.594	15.09	123.11	183.42
24	24	610	0.688	17.48	171.29	255.41

Schedule 80 Steel Pipe Dimensions in mm

Nominal size [inches]	Outside diameter [inches]	Outside diameter [mm]	Wall thickness [inches]	Wall thickness [mm]	Weight [lb/ft]	Weight [kg/m]
1/2	0.84	21.3	0.083	2.11	0.68	1
3/4	1.05	26.7	0.083	2.11	0.87	1.29
1	1.315	33.4	0.109	2.77	1.41	2.11
1 1/4	1.66	42.2	0.109	2.77	1.82	2.71
1 1/2	1.9	48.3	0.109	2.77	2.1	3.13
2	2.375	60.3	0.109	2.77	2.66	3.96
2 1/2	2.875	73	0.12	3.05	3.56	5.29
3	3.5	88.9	0.12	3.05	4.37	6.5
3 1/2	4	101.6	0.12	3.05	5.01	7.46
4	4.5	114.3	0.12	3.05	5.66	8.42
5	5.563	141.3	0.134	3.4	7.82	11.64
6	6.625	168.3	0.134	3.4	9.35	13.91
8	8.625	219.1	0.148	3.76	13.5	20.1
10	10.75	273.1	0.165	4.19	18.79	27.96
12	12.75	323.9	0.18	4.57	24.34	36.22
14	14	355.6	0.188	4.78	27.97	41.62
16	16	406.4	0.188	4.78	32.02	47.65
18	18	457	0.188	4.78	36.05	53.65
20	20	508	0.218	5.54	46.42	69.09
22	22	559	0.218	5.54	51.14	76.1
24	24	610	0.25	6.35	63.93	95.13
30	30	762	0.312	7.92	99.6	148.22

If you are new to the pipe industry, you may wonder why you always see schedule 40 or 80 steel pipes everywhere. What kind of material is used for these pipes?

As you have read above articles you know that Schedule 40 and 80 represent pipe wall thickness, but why are they always searched by buyers?

Here is the reason:

Schedule 40 and 80 steel pipes are commonly required in various industries due to the typical pressure they can withstand. Because these pipes are designed to handle higher pressures, they are often requested in large quantities to meet the demands of different industries.

The material standard for such thickness pipes has no limitations, you could ask for sch 40 stainless steel pipe, like ASTM A312 Grade 316L; Or sch 40 carbon steel pipe, such as API 5L, ASTM A53, ASTM A106B, A 179, A252, A333 etc..

Steel pipe measurements

Before we can read a pipe sizing chart, we need to understand what different measurements or dimensions are being listed.
Length: This is fairly self-explanatory — it designates how long a piece of piping is, usually in standard increments.
Inside diameter (ID): The inside diameter is the distance between the inside walls. It can be thought of as how wide the opening in the pipe is.
Outside diameter (OD): The outside diameter is the distance from the outside edge to its opposite outside edge. This can be thought of as the total “height” of the pipe.
Wall thickness (WT): Similar to length, this is relatively self-explanatory and is the thickness of the piping’s wall. It is also half of the difference between OD and ID. Wall thickness is usually referred to as “schedule” which is a non-dimensional number that needs to be converted to the actual wall thickness using a chart.
Nominal pipe size (NPS): This is the metric that is most often used to convey the “size” of a pipe. However, the NPS is neither the ID nor the OD when it’s between ⅛” and 12”. This means that, while close to the actual diameter of the pipe, it’s another non-dimensional number and more of a designation rather than a measurement. Above 14” (or NPS 14), the nominal pipe size and OD are the same

Dimension standards for steel pipe

Both ASME B36.10 and B36.19 are the standard specifications for the dimensions of the steel pipe and accessories.

ASME B36.10M

As for steel tube dimensions, the actual outside diameter is the same as the pipe number for all sizes.