How to Replace a Door Lock — Deadbolt and Knob Swap Guide

Replacing a door lock upgrades security after a move, lost keys, or worn hardware. A standard deadbolt swap takes under an hour with basic tools. New lock kits include a template and adjustable latch for common backset distances (2-3/8 or 2-3/4 inches). Exterior doors deserve Grade 1 or Grade 2 deadbolts; rekey or match keys if replacing multiple locks.

Materials and Tools

• Replacement lock set (deadbolt, knob, or handleset — same type as removed)
• Phillips and flat screwdrivers or drill with bits (low torque)
• Tape measure
• Optional: chisel and hammer if strike plate depth changes; file; graphite lubricant

Keep old hardware until the new lock works perfectly.

Step 1: Measure and Buy the Correct Lock

1. Note bore hole diameter (often 2-1/8 inch for deadbolt).

2. Measure backset — center of hole to door edge (usually 2-3/8" or 2-3/4").

3. Check door thickness (1-3/8" interior, 1-3/4" exterior typical).

4. For handlesets, match spacing between knob and deadbolt holes.

Adjustable latches in kits fit both common backsets — confirm on packaging.

Step 2: Remove the Old Lock

Deadbolt

1. Open door; remove interior turn-piece or thumb turn mounting screws.

2. Remove two long through-bolts holding interior and exterior halves together.

3. Pull both sides apart.

4. Remove latch assembly screws on door edge; slide latch out.

Knob lock

1. Remove interior knob screw (often under cover plate — pop with flat screwdriver).

2. Pull knobs apart; remove latch screws on edge; extract latch.

Save screws only if new kit lacks correct lengths.

Step 3: Install the New Latch

1. Insert new latch into edge bore with beveled side facing direction door closes.

2. Confirm backset adjustment on latch matches your door (slide tab on many models).

3. Screw latch plate flush to door edge — plate sits flat, not crooked.

If hole is rough or too small, use manufacturer template to enlarge carefully — do not oversize.

Step 4: Mount Exterior and Interior Lock Halves

1. Thread cylinder tailpiece or connecting bar through latch mechanism per instructions — bar length often snaps to size.

2. Align exterior key side and interior turn/knob.

3. Install through-bolts evenly — alternate tightening so halves pull together square.

4. Snug screws — do not crack decorative covers.

Turn interior thumb piece and test key before closing door fully.

Step 5: Adjust and Replace Strike Plate

1. Close door slowly; mark where bolt hits jamb.

2. Align strike plate so bolt enters hole freely without rubbing.

3. If new plate differs from old mortise, chisel wood slightly so plate sits flush.

4. Use long 3-inch screws on strike plate when provided — anchors into stud for kick resistance.

Bolt should extend fully into jamb with no binding.

Step 6: Test Operation and Secure Spares

1. Lock and unlock 10 times with key and interior turn.

2. Check door closes without pushing hard — binding means misalignment; loosen and realign.

3. Store spare keys separately; discard old keys only after confirming new lock works.

Apply graphite (not oil) if key feels sticky — avoid WD-40 in cylinders long term.

Troubleshooting

| Problem | Fix |

|--------|-----|

| Key turns hard | Tailpiece misaligned; bar too long — shorten per instructions |

| Bolt will not throw | Latch upside down; tailpiece disconnected |

| Door will not close | Bolt hitting strike — reposition plate |

| Gap at strike | Shim plate outward with cardboard behind plate |

| Different key than other doors | Buy rekeyable set and rekey to match; or hire locksmith |

| Smart lock install fails | May need specific backset and Wi‑Fi setup — follow smart lock manual |

FAQ

Can I replace a door lock myself?

Yes for standard deadbolts and knob locks on wood doors with existing holes. Commercial doors, smart locks with wiring, or new door prep may need a locksmith.

Should I replace lock when I move?

Rekeying is cheaper if hardware is solid. Replace if worn, cheap builder grade, or keys unaccounted for.

What is backset on a door lock?

Distance from door edge to center of bore hole. Wrong backset makes bolt miss strike plate.

How long does lock replacement take?

30–60 minutes for first-timers; 15–30 once familiar.

Are all deadbolts the same size?

Bore and backset are standardized on modern US doors, but finish, grade, and smart features vary — match measurements before buying.

The Takeaway

To replace a door lock, remove old interior/exterior halves and latch, install new latch at correct backset, connect halves with through-bolts, and align strike plate so the bolt seats fully. Test key and thumb turn before finishing. Use long strike screws on exterior doors for security. Hire a locksmith for non-standard doors or if alignment will not come right after careful adjustment.

*For rental properties, confirm lease rules before changing locks. Some jurisdictions restrict landlord access requirements — check local rules if applicable.*