CPVC Pipe Size Chart in mm and Inches, Plus uPVC
Quick answer: The size printed on a pipe is a name, not a measurement. CPVC is made to copper tube size, so 1/2 inch CPVC measures 15.9 mm outside and 3/4 inch (the 20 mm nominal size) measures 22.2 mm, while uPVC uses iron pipe size and measures 21.34 mm at 1/2 inch and 26.67 mm at 3/4 inch. SWR works differently: a 110 mm SWR pipe is 110 mm across the outside.
The question we get at the counter is nearly always the same one. Somebody holds up a cut piece of pipe and asks whether it is 3/4 inch or 25 mm. The reason it is confusing is that both answers can be right, because the size printed on a pipe is a name, not a measurement.
A 1/2 inch CPVC pipe measures 15.9 mm across the outside. A 1/2 inch uPVC pipe measures 21.34 mm. Neither of them measures half an inch anywhere. Here are the real numbers, for the sizes we actually stock in Viveknagar.
CPVC pipe size chart, 15 mm to 50 mm
CPVC plumbing pipe is made to copper tube size, which is why it is slimmer than everything else on the rack. Outside diameter is fixed for a given size. The class, SDR 11 or SDR 13.5, changes the wall thickness and therefore the bore, not the outside.
| Inch | Nominal mm | Actual outside diameter | Wall, SDR 11 | Wall, SDR 13.5 |
|---|---|---|---|---|
| 1/2 | 15 | 15.9 mm (0.625 in) | 1.73 mm | 1.40 mm |
| 3/4 | 20 | 22.2 mm (0.875 in) | 2.03 mm | 1.65 mm |
| 1 | 25 | 28.6 mm (1.125 in) | 2.59 mm | 2.12 mm |
| 1 1/4 | 32 | 34.9 mm (1.375 in) | 3.18 mm | 2.59 mm |
| 1 1/2 | 40 | 41.3 mm (1.625 in) | 3.76 mm | 3.06 mm |
| 2 | 50 | 54.0 mm (2.125 in) | 4.90 mm | 4.00 mm |
Those figures are from the Astral CPVC PRO catalogue, made to ASTM D2846 and conforming to IS 15778. The BIS product manual for IS 15778 sets the classes: Class 1 is SDR 11 and Class 2 is SDR 13.5, both from 15 mm to 50 mm. Above that the standard moves to Class 3, SDR 17, from 65 mm to 150 mm.
So if you answer "3/4 inch" and the other person answers "20 mm", you are both talking about the same pipe. It measures 22.2 mm.
What SDR actually means
SDR is the standard dimension ratio: outside diameter divided by wall thickness. Check it on the 1 inch row. 28.6 divided by 2.59 is 11.0. On the SDR 13.5 column, 28.6 divided by 2.12 is 13.5. That is the whole idea. A bigger SDR number means a thinner wall relative to the pipe, which means a lower pressure rating and a lower price.
One exception worth knowing, because it looks like an error otherwise. At 1/2 inch the ratio does not hold: 15.9 divided by 1.73 is about 9.2, not 11. Astral's own table footnotes it, saying that at half inch the minimum wall thickness is not a function of SDR. The smallest pipe gets a heavier wall than the ratio would demand so that it survives handling.
CPVC above 2 inch: Schedule 40 and Schedule 80
Past 50 mm, CPVC stops being a copper tube size product and switches to iron pipe size in Schedule 40 and Schedule 80. Different diameters entirely. These are the sizes we carry.
| Inch | Nominal mm | Outside diameter | Bore, SCH 40 | Bore, SCH 80 |
|---|---|---|---|---|
| 2 1/2 | 65 | 73.0 mm | 62.07 mm | 58.14 mm |
| 3 | 80 | 88.9 mm | 77.26 mm | 72.75 mm |
| 4 | 100 | 114.3 mm | 101.55 mm | 95.97 mm |
| 6 | 150 | 168.3 mm | Not in the published table | 145.04 mm |
Read the 4 inch row twice, because it is the point of the whole schedule system. The outside diameter is 114.3 mm in both schedules. Only the bore changes. Schedule 80 has a thicker wall, so the water passage is narrower and the pressure rating is higher. That is why a Schedule 40 fitting and a Schedule 80 fitting of the same size are interchangeable on the outside, and why the two pipes are not interchangeable on flow.
From our shop
Products in this guide
Live dealer prices. Add to cart, or ask for a GST quote on the whole list.
uPVC pipe size chart, Schedule 40 and Schedule 80
uPVC pressure pipe uses iron pipe size from 1/2 inch upward, which is why it is visibly fatter than CPVC at the same stated size. Figures below are from the Astral Aquarius uPVC catalogue, made to the ASTM schedule system.
| Inch | Nominal mm | Outside diameter | Wall, SCH 40 | Wall, SCH 80 |
|---|---|---|---|---|
| 1/2 | 15 | 21.34 mm (0.840 in) | 2.77 mm | 3.73 mm |
| 3/4 | 20 | 26.67 mm (1.050 in) | 2.87 mm | 3.91 mm |
| 1 | 25 | 33.40 mm (1.315 in) | 3.38 mm | 4.55 mm |
| 1 1/4 | 32 | 42.16 mm (1.660 in) | 3.56 mm | 4.85 mm |
| 1 1/2 | 40 | 48.26 mm (1.900 in) | 3.68 mm | 5.08 mm |
| 2 | 50 | 60.32 mm (2.375 in) | 3.91 mm | 5.54 mm |
| 2 1/2 | 65 | 73.02 mm (2.875 in) | 5.16 mm | 7.01 mm |
| 3 | 80 | 88.90 mm (3.500 in) | 5.49 mm | 7.62 mm |
| 4 | 100 | 114.30 mm (4.500 in) | 6.02 mm | 8.56 mm |
Now put the two charts side by side at 1/2 inch. CPVC is 15.9 mm outside, uPVC is 21.34 mm. Same name, 5.44 mm apart. That is the entire reason a CPVC elbow will not go on a uPVC pipe, and we explain what to do about it in CPVC against uPVC.
A caution we would rather give than have you find out on site. Not every brand names its uPVC sizes the same way. Some ranges above 2 inch are listed against a metric outside diameter series instead of the schedule series, so the same inch label can sit on a different pipe. Above 2 inch, confirm the outside diameter for the specific brand before you order fittings, or bring a cut piece to the counter.
SWR pipe: the one where the number is the measurement
SWR drainage pipe works on a completely different logic and this trips up people who have just learned the pressure pipe system. Under IS 13592, SWR pipe comes in Type A and Type B, and the size designation is the nominal outside diameter in millimetres. Type A runs 40 mm to 160 mm and Type B runs 40 mm to 315 mm.
So a 110 mm SWR pipe is 110 mm across the outside. There is no nominal bore to decode. The common stock sizes are 75 mm, 90 mm, 110 mm and 160 mm, and the 110 mm is the one that carries a water closet. Type A is for ventilation and rainwater, Type B is the heavier wall for soil and waste. Our SWR guide for Bengaluru buildings covers where each goes. Tank connections run on their own set of sizes again, which we set out in the Ashirvad water tank guide.
How to measure a pipe you already have
- Measure the outside, not the inside. The bore changes with class. The outside diameter is the fixed identity of the pipe.
- Use a vernier caliper across the pipe if you have one. If you do not, run a tape around the pipe and divide the circumference by 3.14.
- Match the reading to the tables above. Around 16 mm is half inch CPVC. Around 21 mm is half inch uPVC. Around 22 mm is three quarter inch CPVC. Around 27 mm is three quarter inch uPVC.
- Read the print on the pipe. Indian pipe carries the maker, the standard number and the class along the length. That tells you the material and the class without any measuring.
- When in doubt, bring 50 mm of it to the counter. This takes us ten seconds and saves you a return trip. It is the single most useful thing you can put in your pocket before coming.
Quick reference for a house
- 1/2 inch: a single tap or a shower drop. CPVC 15.9 mm, uPVC 21.34 mm.
- 3/4 inch: the workhorse. Bathroom feeds, tank outlets, geyser lines. CPVC 22.2 mm, uPVC 26.67 mm.
- 1 inch: a riser feeding two floors, or the main from a tank on a larger house.
- 2 inch and up: apartment risers and site work, not a flat.
- 110 mm SWR: the toilet line. Not a pressure pipe and not interchangeable with any of the above.
Where to buy it
We stock every size in the CPVC tables at the counter in Viveknagar. The CPVC pipe listing and the uPVC pipe listing show what is live today, and the 2026 Ashirvad CPVC price list has the rates size by size. If you are pricing a full job, reading a plumbing material list explains how the sizes get written on a contractor's sheet. For the codes and tax on any of it, see our GST rate and HSN code guide.
Send your sizes on WhatsApp to 99801 00987, or come to the counter with the offcut.
Questions we get asked
Is 3/4 inch pipe 20 mm or 25 mm?
In CPVC, 3/4 inch is the 20 mm nominal size and the actual outside diameter is 22.2 mm. In uPVC Schedule 40 or 80, 3/4 inch is also called 20 mm and the actual outside diameter is 26.67 mm. The 25 mm size is 1 inch in both systems.
What is the outside diameter of 1/2 inch CPVC pipe?
15.9 mm, or 0.625 inch, in both SDR 11 and SDR 13.5.
Do CPVC and uPVC pipes of the same size fit together?
No. At every size the outside diameters are different. Use a converter coupler made for the purpose.
What is the difference between SCH 40 and SCH 80?
Same outside diameter, thicker wall on Schedule 80, so a smaller bore and a higher pressure rating. A 4 inch pipe is 114.3 mm outside in both.
What size is CPVC pipe for a bathroom?
3/4 inch for the feed into the bathroom and 1/2 inch for the drops to individual taps and the shower, on most Bengaluru homes.
Is 110 mm SWR the same as 4 inch?
People call it 4 inch at the counter, but under IS 13592 the size designation is the outside diameter in millimetres, and the pipe measures 110 mm. Order it by the millimetre figure.
Dimensions on this page were checked on 21 September 2026 against the manufacturers' published catalogues linked above and the BIS product manuals for IS 15778 and IS 13592. Sizes listed are the ones we actually stock. Ring 99801 00987 if you need a size we have not listed.
