Always identify whether the CPVC is CTS, IPS Schedule, or another SDR system before using a dimensional table. The chart below is the CTS SDR 11 system defined by ASTM D2846/D2846M-24, the one used for hot and cold potable water distribution in houses and commercial buildings.

*Calculated ID = OD – 2 x minimum wall. It is a geometric estimate from minimum wall, not a guaranteed or average bore. Millimeter values are converted at 25.4 mm per inch.

Five separate quantities appear in CPVC data. Keep them separate, because mixing them is the most common sizing error.

For broader comparisons across materials, see the Pipe Outside Diameter Chart and the Pipe Inside Diameter Chart. This page stays focused on CPVC.

CTS means Copper Tube Size. CTS CPVC is made to the outside diameters of copper water tube (see the Copper Pipe Size Chart). IPS means Iron Pipe Size. IPS CPVC uses the same outside diameters as steel pipe of the same nominal size.

IPS outside diameters are the standard IPS values used for ASTM F441 Schedule 40 and 80 pipe.

The practical rule: 1-in CTS CPVC has a 1.125 in OD and 1-in IPS CPVC has a 1.315 in OD. A nominal size label alone cannot establish fitting compatibility.

Figure 2. 1-inch CTS and 1-inch IPS CPVC drawn at identical scale. The IPS section is shown with a Schedule 40 wall.

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Do not join CTS and IPS directly

The two systems have different outside diameters. Where they meet, use an approved transition fitting or method.

ASTM D2846/D2846M-24 is the active specification for CPVC hot and cold water distribution systems. It covers pipe and tubing, socket-type fittings, street fittings, plastic-to-metal transition fittings, solvent cements and adhesives made in a single dimension ratio.

• Intended for residential and commercial, hot and cold, potable water distribution.
• CPVC 4120 pipe, tubing and fittings, classified as SDR 11.
• Water service up to and including 180°F (82°C).
• Requirements for materials, workmanship, dimensions and tolerances, hydrostatic sustained pressure strength and thermocycling resistance.
• Intended for chemically compatible pressurized liquids only.

The complete CTS size range in the table above (1/2 through 2 inch nominal) is the range commonly produced by U.S. manufacturers for this system. Larger sizes in the same buildings are usually supplied as IPS Schedule CPVC.

Because SDR is a ratio, every CTS size has the same relative wall. Published tables are still the authority, since very small sizes are governed by a minimum wall and values are rounded to three decimals. For 1/2-in tubing, OD / 11 = 0.057 in, yet the published minimum wall is 0.068 in.

Larger CTS plumbing sizes follow the same SDR 11 pattern. Values below are plain-end CTS dimensions and should be confirmed against the product datasheet.

This section switches from CTS to IPS. ASTM F441/F441M-23 covers CPVC pipe in Schedule 40 and Schedule 80, using the same outside diameters as steel pipe. For the cross-material schedule system, see the Pipe Schedule Chart and the general Schedule 40 Pipe Chart.

*Calculated ID = OD – 2 x minimum wall. IPS dimensions only. Do not mix CTS SDR 11 values into this table. Sizes and availability vary by manufacturer.

Schedule 80 CPVC uses the same IPS outside diameter as Schedule 40 but a thicker wall. For general Schedule 80 references across materials, see the Schedule 80 Pipe Chart.

Approximate weight

Typical published CPVC pipe weights; actual weight depends on the manufacturer and compound.

• Same IPS OD, thicker wall, smaller ID for Schedule 80.
• More material per foot, so more weight and higher cost.
• Pressure capability depends on size, material, temperature and the manufacturer rating, not on the schedule number alone.
• Same nominal size does not mean the same flow area.

The two systems solve different problems. Treat them as separate product families with their own pipe, fittings and ratings.

ASTM F441/F441M-23 covers CPVC pipe made in Schedule 40 and 80 sizes and pressure rated for water. The pipe is intended for chemically compatible pressurized liquids.

• Classification of CPVC pipe materials and a system of nomenclature for CPVC pipe.
• Dimensions, including the Schedule 40 and 80 wall tables.
• Sustained pressure, burst pressure and flattening resistance.
• Workmanship, extrusion quality and marking.

It is a pipe specification. It does not by itself make a product suitable for potable water or approved by a plumbing code.

ASTM F442/F442M covers CPVC pipe made in standard thermoplastic pipe dimension ratios and pressure rated for water. Earlier editions list SDR 11, 13.5, 17, 21, 26 and 32.5, with the pressure rating uniform across sizes for a given material and SDR.

That is why “CPVC equals CTS SDR 11” is not universally correct. Detailed F442 tables are outside the scope of this chart.

CPVC pressure capability depends on the pipe system, size, wall thickness (SDR or Schedule), compound, temperature, the applicable standard and the manufacturer rating. A single number cannot describe all CPVC.

For a cross-material overview of pressure behavior, see the Pipe Pressure Rating Chart.

CPVC loses pressure capability as temperature rises. ASTM D2846 covers hot and cold water service up to and including 180°F, but the allowable pressure at elevated temperature must come from the specific product or system rating. The table below applies published derating factors to a 400 psi at 73°F CTS SDR 11 product.

Reference example only. Factors are those published for ASTM D2846 CTS SDR 11 CPVC piping by manufacturers and distributors; maximum pressure is computed as 400 psi multiplied by the factor, so published tables may show slightly rounded numbers. Use your manufacturer’s table for design. No uprating applies below 73°F.

Compare CPVC with PVC by dimensional system, not by material name. For IPS Schedule 40 and 80, CPVC and PVC share familiar outside diameters and wall thicknesses. CTS SDR 11 CPVC uses copper tube outside diameters, which differ from IPS PVC pressure pipe. The full PVC reference is the PVC Pipe Size Chart.

Never say “CPVC and PVC are the same size” without naming the system. CPVC also tolerates higher service temperatures than PVC, which is why it is used for hot water.

Real hydraulic sizing also depends on length, fittings, pressure, allowable velocity and friction losses. Continue to the Pipe Flow Rate Chart for flow guidance, or the Pipe Volume Chart for the water held per foot.

Fittings must match the pipe’s dimensional system. CTS pipe and tubing go with CTS socket fittings, and IPS Schedule pipe goes with IPS Schedule fittings. Socket dimensions are specific to each system.

• CTS to IPS joints need an approved transition fitting or method, never a forced fit.
• Threaded transitions to metal need the correct CPVC-to-metal fitting. For thread types, see the Pipe Thread Chart.
• ASTM D2846 explicitly includes socket-type fittings and plastic-to-metal transition fittings as part of the system.

Support spacing for CPVC is also system specific. Use the manufacturer’s data and the Pipe Support Spacing Chart only as a general reference.

ASTM F493-22 (2026) covers solvent cements for CPVC pipe, tubing and socket-type fittings. Use cement made for CPVC, not general-purpose or PVC cement, unless the cement is explicitly rated for CPVC.

• Pipe and fitting must be compatible and from the same dimensional system.
• Cut square, deburr and clean the pipe end and socket.
• Follow the manufacturer’s instructions for primer, application, set time and cure time before pressure testing, which vary with size and temperature.

The print line on the pipe tells you what the product actually is. Look for:

• Manufacturer and CPVC material designation.
• Nominal size and the dimensional system (CTS, or IPS with Schedule).
• SDR or Schedule.
• The ASTM standard, such as D2846 or F441.
• Pressure and temperature information where printed.
• Certification marks, for example NSF listings.

The decision path runs from application to standard to size system, then to size, wall, temperature, pressure and fittings.

1. Identify the application.
2. Decide potable water or industrial and process use.
3. Identify the applicable code and project specification.
4. Select the CTS or IPS dimensional system.
5. Select the nominal size.
6. Confirm the actual OD.
7. Select the SDR or Schedule.
8. Confirm wall thickness and ID.
9. Check pressure at the operating temperature.
10. Verify chemical compatibility.
11. Select matching fittings.
12. Select the approved joining system.
13. Verify product certification or listing where required.

If you are comparing CPVC with other residential supply pipe, the PEX Pipe Size Chart and the Pipe Size Chart cover those systems.