What Size Hole Saw for a Doorknob and Deadbolt?

You bought a new deadbolt, opened the box and found a template, a faceplate, a handful of screws and no mention of which drill bit to buy. It is a common moment. Door hardware looks simple until the first hole goes slightly crooked or the latch won't line up with the strike, and a door that does not lock properly is a bigger problem than one that does not look good.

This guide answers the question that sends most people to the hardware aisle: what size hole saw do you need for a doorknob and deadbolt? Then it walks through the full installation in the right order, flags the mistakes that cause most failures and explains the NYC-specific wrinkle that catches apartment dwellers out: fire-rated and building-controlled doors.

1. The Short Answer: Standard Sizes

For nearly all residential doorknobs and deadbolts sold in North America, two holes are required:

Always check the template and instructions supplied with your hardware. Some products use slightly different dimensions, and following the manufacturer's template is always the safest approach. Most door-lock installation kits bundle the 2-1/8 inch hole saw and a 1 inch bit, and some include a jig that clamps to the door to guide the drill.

A hole saw is a cylindrical blade with a center pilot bit. The pilot bit starts the cut and keeps the saw from walking. For doors, choose a saw designed for wood, and use a different one for metal. If you plan to drill steel, do not use a wood saw.

2. Doorknob Versus Deadbolt: What Differs

Both use the same main bore size, which is why people assume the job is identical. The differences lie in position and mechanism.

• Doorknob (or lever) set. The knob sits at a comfortable grip height, typically about 36 inches from the floor to the center of the bore. The latch is a spring-loaded bolt that retracts when you turn the handle.
• Deadbolt. It sits above the knob, commonly 5 to 6 inches above the center of the knob bore, though templates vary. The bolt is a solid piece that extends into the frame and does not retract by spring.

Because the deadbolt bolt is what resists force, its alignment with the strike matters even more than with a knob latch. A bolt that rubs the edge of the strike hole will bind in winter and fail to extend fully. Take your time with this part.

3. Check the Door First

Before you buy a bit or touch a drill, confirm three things.

Door thickness

Standard residential interior doors are often 1-3/8 inches thick, and exterior and entry doors are often 1-3/4 inches. Most locks accommodate both, but check the packaging. Thicker doors may need an extension kit.

Backset

Measure from the edge of the door to the center of the bore. The standard backsets are 2-3/8 inches and 2-3/4 inches. Many locks adjust between them; check the latch before installing.

Material and rating

Is the door solid wood, hollow-core, steel, fiberglass or composite? Each requires slightly different technique. And in New York City, is it an apartment entry door? Those are often steel or steel-faced, and frequently carry a fire rating and label. This is not a detail to skip. Drilling a labeled fire door outside the manufacturer's allowed preparation can compromise the rating, and co-op and condo rules may restrict changes to the door or the lock set.

4. Step-by-Step: Installing a Doorknob or Deadbolt

These steps apply to a standard wood door. Follow your lock's instructions where they differ.

1. Mark the height. Mark the center of the main bore. Many installers use about 36 inches for the knob, and a deadbolt location according to the template.
2. Mark the backset. Use the template to mark the center point on the face of the door, then use a square to carry a line around the edge of the door at the same height.
3. Drill the main bore. Fit the 2-1/8 inch hole saw to the drill. Start slowly with the pilot bit centered on your mark. Drill until the pilot bit just pokes through the other side, then stop.
4. Finish from the opposite face. Move to the other side, place the pilot in the small hole and drill through. Cutting from both sides prevents the splintering that happens when a saw exits.
5. Drill the latch hole. Use a 1 inch bit square to the edge, centered on the line you marked, and drill until it breaks into the main bore. Keep the drill level.
6. Trace and chisel the faceplate. Insert the latch, trace around the faceplate, remove the latch and chisel a shallow mortise so the plate sits flush.
7. Install the lock body. Slide the latch into the edge, install the exterior and interior hardware as directed and tighten the screws evenly.
8. Mark the strike plate. Close the door, mark the latch position on the frame, and drill the 1 inch bolt hole.
9. Mortise and fasten the strike. Chisel the recess for the strike plate and install it.
10. Test. Open and close the door repeatedly with the door open, then closed. The bolt should extend and retract smoothly with no force.

Tips that prevent most problems

• Clamp a scrap block to the exit face when drilling so the wood does not blow out.
• Keep the drill square to the door, not tilted.
• Run the drill at moderate speed, since a hole saw binds if forced.
• Use sharp chisels and light taps; deep cuts split the wood.

5. Strike Plate and Frame: Where Security Is Won or Lost

Many forced entries are not about breaking the lock. They are about splitting the frame at the strike. Strengthening the connection costs very little.

• Use long screws. Replace the short screws that come with some strike plates with screws long enough to reach the framing behind the jamb, commonly around 3 inches. Pick screws with a coarse thread and enough length to bite into solid framing, not just the jamb trim.
• Check for a solid jamb. Cracked or rotted jambs need repair or replacement before you rely on a deadbolt.
• Choose a reinforced strike where the building allows it, and consider a longer strike plate that spans more of the jamb.
• Align the bolt hole carefully. The bolt should enter without rubbing, and extend its full length when locked.

If a frame is soft or rotted from old moisture, repair comes before hardware. Fresh screws in punky wood hold nothing.

6. Common Mistakes to Avoid

Most failed installs come from the same short list.

1. Wrong backset. Drilling at 2-3/4 inches when your lock needs 2-3/8 inches leaves a lock that won't fit. Measure twice, and check the latch.
2. Drilling from one side only. The exit side splinters. Always finish from the opposite face.
3. Crooked holes. An off-square main bore or latch hole makes the lock bind. Use a jig or a helper to check angle.
4. Over-deep mortises. A faceplate or strike set too deep leaves gaps and weakens the wood.
5. Skipping the fire-door check. In apartments and multifamily buildings, drilling a rated door can carry consequences, and building rules may restrict lock changes.
6. Weak strike screws. Short screws turn a strong lock into a weak door.
7. Ignoring the door's condition. A warped or sagging door will not align the bolt no matter how well you drill.
8. Painting over hardware. If the door will be repainted, remove the hardware first and paint the door properly.

7. Planning Ranges When a Door Job Grows

Most lock swaps are simple. But door work often uncovers bigger needs, such as a worn floor under the swing, damaged trim or a door that has been repainted too many times. These are typical 2026 planning ranges for the New York metro area as of October 2026. Building rules, access, hazmat, finishes and scope move prices, and a written, itemized quote governs the final number.

If your door project is part of a larger refresh and you want to see whether it pays back, the renovation ROI calculator is a quick way to check.

8. When a Pro Is the Safer Choice

9. Permits, Co-op Rules and Lock Changes

Door hardware swaps are not typically treated as permit-triggering construction when the door is already prepared and no structure changes. Larger changes are different. In New York City, most construction work needs a Department of Buildings permit, and alterations are filed through DOB NOW: Build by a New York State registered design professional, either a licensed Professional Engineer or a Registered Architect, as Applicant of Record. Cosmetic work such as painting generally does not need a DOB permit, though co-op, condo and landlord rules still apply. The NYC Department of Buildings website is the best official starting point, and our permit checker gives a quick read for your project.

Practical rules to remember:

• Co-ops and condos often require approval to change entry-door locks, and some require a key on file with management.
• Rentals. Landlords usually control locks on entry doors. Check your lease before changing anything.
• Fire-rated doors should be modified only in line with the door's labeling and applicable rules.
• Construction hours. The Noise Code generally limits construction to weekdays about 7 AM to 6 PM, and many buildings restrict work to about 9 AM to 5 PM.
• Long Island and New Jersey. Door and lock changes in one- and two-family homes rarely need permits, but replacing doors or frames, or altering egress, can. Check with your municipality.

10. Neighborhoods and ZIP Codes We Serve

Door conditions depend heavily on the building. Here is what we see in our service area:

• East Village, Manhattan (10003, 10009): tenement walk-ups and small rent-stabilized apartments, where entry doors may be steel and building-controlled and narrow stairs complicate hauling a new door. See our East Village luxury apartment renovations page.
• Boerum Hill, Brooklyn (11201, 11217): brownstones and row houses inside the Boerum Hill Historic District, where original wood doors and frames often deserve repair rather than replacement.
• Woodhaven, Queens (11421): Victorian wood-frame homes and two-families, with old doors and frames that often need rot repair.
• Annadale, Staten Island (10312): detached homes and townhouse complexes, where association rules sometimes govern front-door appearance.
• Woodmere, Nassau County (11598): Five Towns colonials with large entries and village-level permit rules.
• Harrison, Hudson County, NJ (07029): new condos and older multifamily buildings, where fire-rated entry doors and NJ Uniform Construction Code rules apply.

We also serve the rest of the five boroughs, Long Island and northern and central New Jersey within roughly a 50-minute drive.

11. Next Steps: Get Your Door Project Done Right

James - Lead Renovation Editor. With over 20 years in renovation and construction, James writes and edits our guides. More about James