PVC 101: Finding Your PVC Pipe Size
The Short Answer
PVC pipe size is a nominal size: a name that does not exactly equal the outside diameter or the inside diameter. To find your size, measure the outside diameter (OD) and match it to the chart on this page, or use our printable PVC Size Guide.
If you can only measure the inside, Schedule 40 pipe has an inside diameter (ID) close to its size name, usually within about 1/8". Use it as a starting point, then confirm on the chart.
Internal-fit parts, such as internal couplers and caps, fit inside the pipe, so they also depend on the pipe schedule. FORMUFIT internal-fit products work only with Schedule 40 pipe.
Anatomy of a PVC Pipe
To understand PVC size basics, it's essential to know all the names of the elements that make up a PVC pipe:
- Outside Diameter (OD): the distance across the full outside of the pipe. Slip fittings fit over the OD.
- Inside Diameter (ID): the distance across the hollow center, also called the bore. Internal-fit parts fit inside the ID.
- Wall (Schedule): the distance from the inside surface to the outside surface. The schedule (Schedule 40 or Schedule 80) sets the wall thickness for each size.
Four Ways to Find Your PVC Pipe Size
Use our printable PVC Size Guide
Print the guide at full scale, or open it on a phone or tablet, and hold your pipe against each size outline.
Open the PVC Size Guide
Read the PVC Pipe Markings
Plumbing-grade pipe is printed with its nominal size and schedule, but each manufacturer formats the markings differently. Our markings page shows how to read them. FORMUFIT Furniture Grade pipe is mark free, so this method applies to plumbing-grade pipe.
How to Read Pipe Markings
Compare Pipe to Everyday Objects
Use our comparison chart to match each size to common household objects. It gives a quick estimate, so confirm the size with the size guide or the dimensions chart.
View the Pipe Comparison Chart
Match Outside Diameter to the Chart
Hold a tape measure across the end of the pipe, edge to edge, or use calipers, and read the outside diameter. Then find the matching size on the dimensions chart.
PVC Size Dimensions Chart
PVC Pipe Size Chart
Measure the outside diameter of your pipe and find the matching row. The nominal size in the first column is the size you order.
| Nominal size | Outside diameter (OD) | OD as a tape measure fraction | Sch 40 minimum wall | Sch 40 inside diameter (ID) | Sch 80 minimum wall | Sch 80 inside diameter (ID) |
|---|---|---|---|---|---|---|
| 1/2" | 0.840" | 13/16" | 0.109" | 0.622" | 0.147" | 0.546" |
| 3/4" | 1.050" | 1-1/16" | 0.113" | 0.824" | 0.154" | 0.742" |
| 1" | 1.315" | 1-5/16" | 0.133" | 1.049" | 0.179" | 0.957" |
| 1-1/4" | 1.660" | 1-5/8" | 0.140" | 1.380" | 0.191" | 1.278" |
| 1-1/2" | 1.900" | 1-7/8" | 0.145" | 1.610" | 0.200" | 1.500" |
| 2" | 2.375" | 2-3/8" | 0.154" | 2.067" | 0.218" | 1.939" |
The outside diameter is the same for Schedule 40 and Schedule 80. The fraction column shows the closest tape measure mark to the outside diameter. Outside diameters and minimum wall thicknesses follow ASTM D1785 for iron pipe size PVC. Inside diameters are the outside diameter minus twice the minimum wall, and actual pipe varies slightly within the standard tolerances. Reviewed October 2026.
How PVC Pipe Size Works
FORMUFIT fittings and accessories come in six PVC sizes: 1/2", 3/4", 1", 1-1/4", 1-1/2" and 2". They work with FORMUFIT Furniture Grade pipe and with most plumbing-grade Schedule 40 PVC pipe.
Before you order, keep three things in mind: the size is a nominal name, the schedule matters for internal-fit parts, and not every type of pipe is compatible.
PVC Pipe Size Is a Nominal Name, Not a Measurement
PVC pipe sizes follow the Nominal Pipe Size (NPS) system. The size name, such as 3/4" or 1", is a label. It does not exactly equal the outside diameter or the inside diameter. The OD is always larger than the size name, a holdover from older pipe standards.
For example, 3/4" Schedule 40 pipe has an OD of 1.050" and an ID of about 0.824", and 1" pipe has an OD of 1.315" and an ID of about 1.049".
On Schedule 40 pipe, the inside diameter is the closer of the two to the size name, usually within about 1/8". That makes a quick measurement across the bore a useful clue, but it is not exact, so always confirm the size on the chart.
The Reliable Way: Measure the Outside Diameter
Hold a tape measure across the end of the pipe, edge to edge, or use calipers, and read the outside diameter. Then match the reading to the PVC Pipe Size Chart on this page to find the nominal size. Do not read the OD as the size: a pipe with an OD of about 1.050" is a 3/4" pipe, not a 1" pipe.
A Quick Clue: Measure the Inside Diameter
If you cannot measure the outside, measure across the inside of the pipe. On Schedule 40 pipe the inside diameter is close to the size name, usually within about 1/8". For example, an ID near 1.05" points to 1" pipe, and an ID near 0.82" points to 3/4" pipe. Treat it as a starting point only. The ID is never exactly the size, it gets smaller on Schedule 80 pipe, and it is hard to measure accurately, so confirm the size on the chart or with the PVC Size Guide.
PVC Schedule, Visualized
As the PVC schedule number increases, the pipe wall gets thicker, and the inside diameter gets smaller. This chart shows which FORMUFIT products are compatible with each schedule of PVC pipe.
Not All Pipe Is Compatible
Not every type of pipe works with FORMUFIT fittings and accessories. PVC fittings are made for iron pipe size PVC, while many other pipes, tubes and rods are sized by a different system, often the outside diameter. Some materials also cannot be joined with PVC cement, and plastic is difficult to connect to wood or metal.
CTS and CPVC Pipe
Copper Tube Size (CTS) CPVC pipe is the most commonly confused pipe. It uses a different sizing system and is not compatible with FORMUFIT products. See our CPVC Incompatibility page for details.
ABS Pipe
ABS pipe is size-compatible with most FORMUFIT products, but it needs a transition cement made for ABS to PVC joints, or a screwed connection. ABS is also brittle and breaks easily, so we do not recommend it for structural projects.
Poly Pipe (Polypropylene and Polyethylene)
Poly pipe is commonly used for sprinklers and irrigation. It is flexible but fragile, and some poly pipe matches Schedule 40 and 80 dimensions. It connects with compression or barbed connectors, not slip fittings, and it cannot be joined to PVC fittings with PVC cement.
Acrylic Tube and Rod
Acrylic looks similar to PVC, but it is sized by its outside diameter, so it is not dimensionally compatible.
Steel Conduit and Pipe
Some steel pipe has the same outside diameter as PVC of the same size, but there is no way to connect steel pipe to a plastic fitting. Metal EMT conduit uses a separate sizing system and does not fit PVC fittings or accessories.
Wooden Dowels
Dowels are sized by their outside diameter, which does not match PVC sizing, so they do not fit securely in PVC fittings.
PVC Size FAQ
PVC pipe size is a nominal size under the Nominal Pipe Size (NPS) system. It is a name, not a measurement, and it does not equal the outside diameter or the inside diameter of the pipe.
Measure the outside diameter, then match it to a PVC pipe size chart. Do not read the OD as the size, because a pipe with an OD of 1.050" is a 3/4" pipe. If you can only measure the inside, Schedule 40 pipe has an inside diameter close to its size name, usually within about 1/8", so it gives you a starting point. Confirm the size on the chart.
Print the FORMUFIT PVC Size Guide, or open it on a phone or tablet, and compare your pipe to each size at full scale. You can also match the outside diameter of your pipe to the PVC Pipe Size Dimensions Chart.
Close, but not exactly. Schedule 40 pipe has an inside diameter of 0.622" for 1/2", 0.824" for 3/4", 1.049" for 1", 1.380" for 1-1/4", 1.610" for 1-1/2" and 2.067" for 2". The inside diameter is the closest measurement to the size name, but the name is not the inside diameter, so confirm the size on the chart.
The outside diameters are 0.840" for 1/2", 1.050" for 3/4", 1.315" for 1", 1.660" for 1-1/4", 1.900" for 1-1/2" and 2.375" for 2". They are the same for Schedule 40 and Schedule 80.
The schedule sets the wall thickness. Schedule 80 has thicker walls than Schedule 40, which makes it stronger but gives it a smaller inside diameter. The outside diameter is the same.
Internal-fit parts slide inside the pipe, so the wall thickness affects the fit. FORMUFIT internal-fit products are made for the inside diameter of Schedule 40 pipe and work only with Schedule 40.
Yes. FORMUFIT fittings work with most plumbing-grade Schedule 40 PVC pipe. Always confirm that the pipe size and schedule match the fitting type before assembly.
No. CTS CPVC, acrylic, poly (polypropylene and polyethylene) and ABS pipe use different sizing or materials and may not connect properly. Verify compatibility before using any non-PVC material.
No. Copper Tube Size (CTS) CPVC pipe uses a different sizing system and will not fit PVC fittings. See the CPVC Incompatibility page for details.
No. ABS is dimensionally similar to PVC, but it is more brittle and prone to breaking. It should be used only with a transition cement made for ABS to PVC joints, or with threaded connections.
Wood dowels, acrylic tube and most conduit are sized by their outside diameter, which does not match PVC sizing. Steel pipe also cannot be joined to plastic fittings.