Common hole saw sizes in US construction range from 3/4 to 4-1/4 inches, with the right size depending on the pipe, conduit, or fixture’s outside diameter.
For the full breakdown, see our best 2-7/8″ Hole Saw guide.
Picking a hole saw by guessing usually ends with a sloppy fit or a ruined door. The common hole saw sizes used in electrical, plumbing, carpentry, and HVAC work cluster around specific dimensions tied to real-world fixtures, and knowing which size matches which job saves a second trip to the hardware store.
Standard Hole Saw Sizes and Their Jobs
The most common hole saw sizes in US work are 3/4 in, 7/8 in, 1 in, 1-1/8 in, 1-3/8 in, 1-1/2 in, 1-3/4 in, 2 in, 2-1/8 in, 2-1/2 in, 2-5/8 in, 3 in, 3-1/2 in, 4 in, and 4-1/4 in. Each size maps to a typical use.
- 7/8 in — 1/2 in conduit knockouts
- 1-1/8 in — 3/4 in EMT conduit knockouts
- 1-3/8 in — 1 in EMT conduit and deadbolt edge bores
- 2-1/8 in — standard residential door knob lockset boring
- 3-1/2 in — dryer vent lines
- 4-1/4 in — some electrical and HVAC rough-ins
These groupings come from published hole saw sizing charts, like the hole saw sizing chart from NDR Electric, which lists recommended cutouts for conduit and common fixtures.
Match the Outside Diameter, Not the Nominal Size
The single most common mistake is matching a hole saw to a pipe’s nominal size instead of its real outside diameter plus the clearance the fitting needs. A 1-inch pipe is not 1 inch across; it’s larger, and the cutout must clear the widest part of the fitting.
Hole saw sizes are not universal for every fixture. Downlights and specialty fittings often require a specific cutout diameter that only the manufacturer’s spec sheet provides. When the fixture calls for an exact opening, trust that number over any general chart.
Depth and Special Cases
Larger and deeper cuts may require specialty hole saws. Standard portable-drill hole saw diameters typically range from 1/4 in to 6 in, with common depths of 38 mm, 45 mm, and 60 mm. That depth matters: a 4-inch cut through a 2×4 is different from the same diameter through a solid door, and usable depth varies by product.
| Hole Saw Size | Typical Use | Fit Note |
|---|---|---|
| 7/8 in | 1/2 in conduit knockouts | Snug fit for the connector |
| 1-1/8 in | 3/4 in EMT conduit | Allows cable movement |
| 1-3/8 in | 1 in EMT, deadbolt edge | Two different jobs share this size |
| 2-1/8 in | Door knob lockset | Standard residential bore |
| 3-1/2 in | Dryer vent line | Matches common vent hoods |
| 4-1/4 in | Electrical, HVAC rough-in | Check fixture spec first |
When cutting metal, slower speed and cutting fluid extend blade life. When cutting wood, a pilot bit that bites first keeps the saw from walking across the surface.
FAQs
What size hole saw do I need for a deadbolt?
A 1-3/8 in hole saw handles the edge bore for most residential deadbolts. The latch edge also needs a separate shallower bore with a smaller bit. Always confirm the deadbolt manufacturer’s template, since some brands vary slightly from the standard.
Does a bigger hole saw work for smaller conduit?
It will fit, but the knockout or connector may not grip properly, and the gap can look unfinished. For a tight, code-friendly result, use the size the conduit chart specifies: 7/8 in for 1/2 in conduit, 1-1/8 in for 3/4 in EMT.
Are hole saw sizes universal across brands?
The cutting diameter is standard across brands; a 2-1/8 in saw from any major manufacturer cuts the same 2-1/8 in hole. What varies is arbor compatibility, depth rating, and tooth quality. Check the arbor size before buying a set.
References & Sources
- NDR Electric. “Hole Saw Sizing Chart.” Lists recommended cutout diameters for conduit and common fixtures.
- NDR Electric. “Hole Saw Sizing Chart (Second Edition).” Confirms typical sizes and applications.
- Wikipedia. “Hole Saw.” Documents typical diameter ranges and common depths.