PVC Pipe Sizes Chart: Schedule 40 & 80 Dimensions (OD, ID, Wall)

PVC pipe isn't measured by the diameter you can see — it's labelled by Nominal Pipe Size (NPS), a legacy system where the number only approximates the bore. That trips up a lot of first-time buyers. This reference gives the actual outside diameter, wall thickness and inside diameter for Schedule 40 and Schedule 80 PVC-U, plus a quick guide to reading the chart correctly.

How PVC sizing works (NPS)

Nominal Pipe Size (NPS) is a label, not a measurement. Historically the NPS number was roughly the inside diameter, but modern wall thicknesses mean it no longer matches any single dimension. What is fixed is the outside diameter: for a given NPS, the OD is identical across Schedule 40, 80 and 120 — which is exactly why the same fittings fit every schedule.

Schedule 40 PVC dimensions

Schedule 40 is the general-purpose class for cold water, irrigation and drainage. Dimensions in inches, to ASTM D1785 (verify against your manufacturer's data for the exact tolerance):

Schedule 80 PVC dimensions

Schedule 80 shares each size's outside diameter with Schedule 40 but has a thicker wall — so a higher pressure rating and a smaller inside diameter. Dimensions in inches, to ASTM D1785:

How to read the chart

• Match by NPS and OD, not by the nominal number — that is what makes fittings interchange across schedules.
• Use the inside diameter (ID), not the nominal size, when you calculate flow velocity or head loss.
• Note that Schedule 80 of the same size has a smaller ID, so it flows slightly less than Schedule 40.
• For threaded joints, remember threading removes wall — Schedule 80 is preferred because it has wall to spare.

The bottom line

Size PVC by NPS and outside diameter so your fittings match, then use the real inside diameter to check flow. Pick Schedule 40 for moderate-pressure cold water and drainage, Schedule 80 where pressure, threading or exposure demand a thicker wall. When you need pipe rated by pressure class (PN/SDR) or for hot service, look at metric ISO 1452 PVC or CPVC instead.

PVC sizing glossary

NPS (Nominal Pipe Size)

The size label (e.g. 2") that fixes the outside diameter; it only approximates the bore.

OD (Outside Diameter)

The pipe's external diameter — identical across schedules at a given NPS, so fittings interchange.

ID (Inside Diameter)

The bore. Smaller for higher schedules; the value to use for flow and head-loss calculations.

Wall thickness

The pipe wall dimension that sets the schedule and, with it, the pressure rating.

Schedule

A wall-thickness class (40, 80, 120). Higher schedule = thicker wall = higher pressure, smaller bore.

References & standards

1. [1]ASTM International — ASTM D1785 — PVC Plastic Pipe, Schedules 40, 80 and 120
2. [2]ISO — ISO 1452 — Plastics piping systems for water supply (PVC-U)
3. [3]Commercial Industrial Supply — PVC piping sizing charts (Sch 40 / Sch 80)
4. [4]PVC Fittings Online — PVC pipe dimensions 1/8" through 24"
5. [5]Petersen Products — PVC & CPVC pipe size chart
6. [6]Plastics Pipe Institute (PPI) — Handbook of PVC Pipe