What size hole saw for pipe?
Pick the pipe, its size, and where it's going. You get the hole saw, with an easy-clearance size and an exact fit.
Pipe
Nominal size
The size printed on the pipe. Under it, the pipe’s real outside diameter.
Where it’s going
Easy clearance hole saw
Get the gear
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Why the hole isn’t the pipe’s size
Pipe is sold by a nominal size, a name rather than a measurement, just like lumber. 2" PVC measures 2.375" across and 1/2" copper 0.625", so the hole saw is always bigger than the number on the pipe. You get two answers: easy clearance (the default, about 1/16" around the pipe for movement and an imperfect cut) and the exact fit, the smallest saw at least the pipe’s size. Conduit going into a box is different again: that hole is sized for the connector, so it follows the knockout size, not the pipe.
Before you cut
- In studs and joists, the building code limits the hole by the lumber’s real depth: see how big a hole you can drill in a stud.
- PEX through steel studs needs a grommet or sleeve, per Uponor, Zurn and the PEX industry design guide. In wood, Zurn says a hole at least 1/8" bigger than the tube needs none.
- For a steel box or panel, see what drill bit for metal; a knockout punch is the other way to make the hole.
- Through concrete or block, a hole saw isn’t the tool: see what drill bit for concrete.
Common questions
What size hole saw for 2 inch PVC?
2" PVC is 2.375" across, so use a 2-1/2" hole saw for easy clearance, or 2-3/8" for an exact fit (zero clearance: it can bind, or not pass pipe at the top of its tolerance). A 2" saw is far too small. Schedule 40 and 80 are the same outside size.
What size hole saw for 1/2 inch conduit?
Into a box or panel, use a 7/8" hole saw: the standard knockout for 1/2" conduit, the same for EMT, PVC and rigid. Passing it through a stud, use 1" for PVC or rigid conduit (0.840" across) or 7/8" for EMT (0.706" across).
Why is the hole saw bigger than the pipe size?
Because pipe sizes are names, not measurements. PVC, ABS and conduit use nominal pipe sizes whose real outside diameter is larger, and copper and PEX are 1/8" bigger than their name. The hole has to clear the real outside diameter.
What size hole saw for 1/2 inch PEX or copper?
1/2" PEX and copper are both 0.625" across. A 3/4" hole saw leaves about 1/16" around the tube; Zurn says a hole at least 1/8" bigger than the tube needs no sleeve in wood. 5/8" is an exact fit with no clearance. In steel studs, PEX makers call for grommets or sleeves.
Can I use a 2 inch hole saw for 1-1/2 inch PVC?
Yes. 1-1/2" PVC is 1.900" across, so a 2" saw clears it by about 0.05" each side: snug but workable. 2-1/16" is the easy-clearance size if you have it.
Full hole saw chart
Hole saw size chart for pipe and conduit
| PVC / ABS | Actual OD | Easy clearance | Exact fit | Clear a coupling |
|---|---|---|---|---|
| 1/2" | 0.840"21.3 mm | 1"25.4 mm | 7/8"22.2 mm | 1-5/16"hub 1-3/32" |
| 3/4" | 1.050"26.7 mm | 1-3/16"30.2 mm | 1-1/16"27 mm | 1-7/16"hub 1-5/16" |
| 1" | 1.315"33.4 mm | 1-1/2"38.1 mm | 1-3/8"34.9 mm | 1-3/4"hub 1-5/8" |
| 1-1/4" | 1.660"42.2 mm | 1-13/16"46 mm | 1-11/16"42.9 mm | 2-1/8"hub 1-31/32" |
| 1-1/2" | 1.900"48.3 mm | 2-1/16"52.4 mm | 1-15/16"49.2 mm | 2-3/8"hub 2-7/32" |
| 2" | 2.375"60.3 mm | 2-1/2"63.5 mm | 2-3/8"zero clearance | 2-7/8"hub 2-3/4" |
| 2-1/2" | 2.875"73 mm | 3"76.2 mm | 2-7/8"zero clearance | 3-1/2"hub 3-11/32" |
| 3" | 3.500"88.9 mm | 3-5/8"92.1 mm | 3-1/2"zero clearance | 4-1/8"hub 4" |
| 4" | 4.500"114.3 mm | 4-5/8"117.5 mm | 4-1/2"zero clearance | 5-1/2"hub 5-1/32" |
| Copper / PEX | Actual OD | Easy clearance | Exact fit |
|---|---|---|---|
| 3/8" | 0.500"12.7 mm | 5/8"15.9 mm | 9/16"14.3 mm |
| 1/2" | 0.625"15.9 mm | 3/4"19 mm | 5/8"zero clearance |
| 3/4" | 0.875"22.2 mm | 1"25.4 mm | 7/8"zero clearance |
| 1" | 1.125"28.6 mm | 1-5/16"33.3 mm | 1-1/8"zero clearance |
| 1-1/4" | 1.375"34.9 mm | 1-1/2"38.1 mm | 1-3/8"zero clearance |
| 1-1/2" | 1.625"41.3 mm | 1-3/4"44.4 mm | 1-5/8"zero clearance |
| 2" | 2.125"54 mm | 2-1/4"57.2 mm | 2-1/8"zero clearance |
| Conduit | Into a box | Through, PVC / rigid | Through, EMT |
|---|---|---|---|
| 1/2" | 7/8"NEMA 0.875" | 1"exact 7/8" | 7/8"exact 3/4" |
| 3/4" | 1-1/8"NEMA 1.109" | 1-3/16"exact 1-1/16" | 1-1/16"exact 15/16" |
| 1" | 1-3/8"NEMA 1.375" | 1-1/2"exact 1-3/8" | 1-5/16"exact 1-3/16" |
| 1-1/4" | 1-3/4"NEMA 1.734" | 1-13/16"exact 1-11/16" | 1-11/16"exact 1-9/16" |
| 1-1/2" | 2"NEMA 1.984" | 2-1/16"exact 1-15/16" | 1-7/8"exact 1-3/4" |
| 2" | 2-1/2"NEMA 2.469" | 2-1/2"exact 2-3/8" | 2-3/8"exact 2-1/4" |
| 2-1/2" | 3"NEMA 2.969" | 3"exact 2-7/8" | n/a |
| 3" | 3-5/8"NEMA 3.594" | 3-5/8"exact 3-1/2" | n/a |
| 4" | 4-5/8"NEMA 4.641" | 4-5/8"exact 4-1/2" | n/a |
Easy clearance = smallest saw at least 1/8" over the pipe’s outside diameter (about 1/16" around it), the default. Exact fit = smallest saw at least the pipe’s outside diameter; “zero clearance” means the saw equals the pipe’s nominal outside diameter: it can bind, and pipe at the top of its tolerance won’t pass. Clear a coupling = the Sch 40 coupling hub plus 1/8". Into a box, conduit follows the NEMA knockout for the trade size, the same for EMT, PVC and rigid.
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Where these numbers come from
Outside diameters are copied from the makers’ and standards’ published tables. The hole saw sizes are not typed in: they’re worked out from those diameters and the sizes saw makers actually sell, then checked at build time so a recommended hole can never be smaller than what has to pass through it. Easy clearance is the smallest saw at least 1/8" bigger than the pipe; exact fit is the smallest saw at least the pipe’s size. Millimetres are converted from inches, not copied.
- JM Eagle, Solvent Weld Schedule Series submittal (PVC Sch 40/80, ASTM D1785/D2665)
- Charlotte Pipe, PVC DWV submittal
- Charlotte Pipe, ABS submittal
- Copper Development Association, Copper Tube Handbook, Tables 14.2a–c (ASTM B88)
- Uponor, Plumbing Design Assistance Manual (PEX is copper tube size)
- Atkore / Allied, EMT submittal (UL 797 / ANSI C80.3)
- Atkore / Allied, rigid conduit (GRC) sheet (UL 6 / ANSI C80.1)
- Atkore Heritage Plastics, PVC conduit catalog (UL 651 / NEMA TC 2)
- Spears, Schedule 40 PVC coupling technical sheets (fig. 429)
- NEMA Engineering Bulletin No. 71, Knockout Diameters and Fitting Dimensions
- Greenlee, Slug-Buster knockout punch catalog
- Milwaukee, Knockout System hole guide
- Lenox, Hole Saws & Accessories catalog (sizes sold; pipe-entrance table)
- Starrett, Saws & Hand Tools catalogue (bi-metal sizes)
- Zurn, PEX Plumbing Installation Guide (ZMKTG370-04)
- Uponor, Residential Plumbing Installation Guide
- PPI / PPFA, PEX Design Guide, 2nd ed., ch. 9
General sizing guidance from published pipe, conduit and hole saw dimensions. Before boring framing, check the hole limits in your local building code; for electrical work, follow your local electrical code and the fitting maker's instructions.