PVC Pipe Sizes

The Walls Match Too, Almost Exactly

Of the 52 size-and-schedule combinations where both materials publish a wall, 41 carry the identical figure. 11 differ — and every single one differs by exactly one thousandth of an inch, with PVC the thinner. That is not a different pipe. It is ASTM truncating a converted figure where ASME rounds it half up.

The Number Is the Same. The Promise Is Not.

Here is what the matching tables conceal, and it is the only thing on this page that will cost anyone money.

ASTM D1785 publishes a minimum wall

0.154 in at 2-inch schedule 40 means the wall will not be thinner than 0.154 in. It is a floor.

ASME B36.10M-2015 publishes a nominal wall

The same 0.154 in on a steel pipe is a target, and the standard permits a mill under-tolerance of 12.5 per cent against it. A steel pipe printed at 0.154 in may be delivered at 0.1348 in and be entirely within specification.

So two tables printing one number are making two different promises, and the plastic one is the stricter. Any calculation that reads a wall off a chart and calls it “the” wall — bore, flow area, weight, pressure — is resting on which standard the pipe was made to, not on the figure printed in the cell.

PVC Dimensions by Schedule

SCH 40

SCH 80

SCH 120

Showing ASTM D1785. 32 of 61 rows verified: each had to match the ASME diameter series, agree with its own published bore or weight, and be carried by two publishers that are not copying each other. How this data was verified.

What We Could Not Verify

29 of the 61 rows are published carrying a visible label rather than dropped. 15 of them are schedule 120, and the reason is worth stating plainly: only one publisher in our set carries that schedule, and it prints neither a bore nor a weight — so there is nothing on the page to check the wall against.

We could have checked those walls against the steel schedule 120 figures, and deliberately did not. The finding this page reports is that PVC walls track the steel walls; using that as the test would be assuming the conclusion and then reporting it as evidence. So they stay labelled until a second independent publisher is found.

PVC Against the Other Materials

The other plastic on this series is HDPE pipe sizes, and the two borrow it differently: PVC takes the steel diameters and the schedule names with them, while HDPE takes the diameters and replaces the schedule with a ratio.

PVC is the material that shares the steel series most completely. Galvanized pipe sizes shares it because galvanized pipe is steel; stainless steel pipe sizes shares the diameters on a series of its own walls. The two that do not share it at all are copper pipe sizes, which is named an eighth of an inch below its own diameter, and ductile iron pipe sizes, which runs diameters of its own entirely.

For what the schedule number specifies before any material is chosen, see how the pipe schedule system works, and for the most-specified of them, schedule 40 pipe dimensions.

Frequently Asked Questions

What is the outside diameter of 2-inch PVC pipe?

2.375 inches — 60.32 mm — which is exactly the outside diameter of 2-inch steel pipe. PVC schedule 40 and 80 run on the IPS series, the same diameters ASME B36.10M fixes for steel, so the two take the same nominal sizes and the same fittings geometry.

Is PVC pipe the same size as steel pipe?

On the outside, yes. Every row here is required to match the ASME diameter at its nominal size before it may publish, and all 61 do. The walls are nearly identical too: 41 of 52 are the same number as the steel wall, and the 11 that differ are all exactly one thousandth of an inch thinner — ASTM truncating where ASME rounds up.

If the numbers are the same, is PVC schedule 40 the same as steel schedule 40?

No, and this is the part the identical table hides. ASTM D1785 publishes a MINIMUM wall: 0.154 in means no thinner than that. ASME B36.10M publishes a NOMINAL wall carrying a −12.5% mill tolerance, so a steel pipe printed at 0.154 in may legally be delivered at 0.1348 in. Two identical printed figures, two different guarantees.

Does PVC use schedules like steel?

It uses the same schedule names — 40, 80 and 120 — on the same diameters, which is why the tables look interchangeable. What a schedule number means is unchanged: it sets the wall, not the diameter. The bore therefore shrinks as the schedule rises, exactly as it does in steel.

Why is PVC pipe rated by pressure as well as by schedule?

Because a schedule is a thickness and not a strength, and plastic's strength depends on temperature in a way steel's does not at ordinary service conditions. Pressure-rated PVC is a separate series designated by SDR rather than by schedule, and it is not covered by the tables on this page.