Best Measuring Tools for Door Lock Installation: 5 Picks for a Perfect Fit

Measuring a door for a lock comes down to three numbers — handle height, backset, and bore diameter — and getting any one of them wrong means a lock that binds, rattles, or won’t sit flush. This roundup covers five tools that take the guesswork out of that measurement and installation work: a drilling jig for new locksets, a mortise template for latch plates, a compact measuring wrench, a keyhole lockout cover, and a reinforcement latch for added security. DIY homeowners replacing a single knob, handymen fitting out a rental, and locksmiths who want a repeatable setup will all find a match below. The overview table sums up each pick before the detailed reviews.

Overview of the Picks

Product	Key Spec	Best Use	Price Tier
Keyed Door Handle Lockout Device Cover	Combination lock, long connecting shaft	Restricting keyhole access from outside	Budget
Door Knob Drilling Kit	Fits 1-3/8"–1-3/4" doors, guide template	Drilling fresh lockset holes	Budget
Combination Wrenches Lock Wrench Measuring Tool	Heavy-duty steel, accurate scale	On-the-spot measurement and adjustment	Budget
Door Latch Mortise Tool for Router	Aluminum alloy, fits 1" x 2-1/4" latch plates	Routing latch plate mortises	Mid-range
Child Proof Door Lock Night Flip Latch	800 lb withstand, 8 screws included	Reinforcing an inward-swinging door	Budget

1. Keyed Door Handle Lockout Device Cover

Type: Keyhole lockout cover
Lock style: Combination lock with code
Mounting: Fits handle locks with a long connecting shaft
Access: Disables keyhole access from outside only
Best for: Bedroom and interior doors

Keyed Door Handle Lockout Device Cover with Code to Disable Access to Keyhole Combination Lock for Bedroom from Outside Only Fits Handle Lock with Long Connecting Shaft Please Measure Before Order

Check the current price on Amazon

This cover slips over an existing handle lock and blocks the keyhole from the outside, replacing keyed entry with a combination code. The long connecting shaft is the critical dimension — the cover only works on handles whose shaft length matches its fitting, which is why the manufacturer asks buyers to measure before ordering. It suits renters and homeowners who want to lock down a bedroom or home office without swapping the whole lockset.

Trade-off: The fit is shaft-length specific, so a handle that measures even slightly off will not accept the cover, and the code mechanism adds one more thing to remember in an emergency.

2. Door Knob Drilling Kit

Type: Lock installation drilling kit
Door fit: Standard wood doors, 1-3/8"–1-3/4" thick
Included: Guide template and hole saw
Use: Lockset installation or replacement
Best for: New bore holes in wood doors

Door Knob Drilling Kit Fits Standard Wood Doors with Guide Template, Hole Saw for Lockset Installation or Replacement KATA 1-3/8" – 1-3/4" Door Lock Installation Kit for Wood Doors

Check the current price on Amazon

The guide template clamps to the door and sets both the bore and the latch hole at the correct height and backset, while the hole saw cuts clean circles through standard wood doors. This is the tool that turns the measuring step into a physical jig, so the lock lands where it should on the first try. It fits doors from 1-3/8" to 1-3/4" thick, covering most interior and exterior wood slabs.

Trade-off: The kit is built for wood doors only, and the template only pays off if it is aligned and clamped carefully — a slipped template produces an off-center hole that no lockset will cover.

3. Combination Wrenches Lock Wrench Measuring Tool

Type: Multi-function lock wrench and measuring tool
Material: Heavy-duty steel
Scale: Accurate measurement markings
Color: White
Best for: Locksmiths and door repair work

Combination Wrenches, Heavy Duty Steel Lock Wrench Multi-Function Measuring Tool Accurate Scale for Professional Locksmith Door Repair White(Long)

Check the current price on Amazon

This steel wrench pairs a measuring scale with wrench flats, so a single tool handles both sizing a lock component and turning it. The long version gives extra reach for recessed hardware, and the heavy-duty steel construction suits repeated shop use. It earns its place as the pocket tool a locksmith or handyman keeps on the job for quick checks.

Trade-off: It is a hand tool with a fixed scale, so it measures what it can reach and nothing more — buyers needing precise bore placement still need a template or jig.

4. Door Latch Mortise Tool for Router

Type: Router mortise template kit
Material: Aluminum alloy
Door fit: 1-3/8" and 1-3/4" wood doors
Latch plate size: 1" x 2-1/4"
Not for: Strike plates
Best for: Clean latch plate recesses

Door Latch Mortise Tool for Router, Aluminum Alloy Door Latch Plate Template Kit, Door Lock & Door Installation Kit, Fits 1-3/8" & 1-3/4" Wood Doors, for 1" x2-1/4 Latch Plates, Not for Strike Plate

Check the current price on Amazon

This aluminum template clamps to the door edge and guides a router to cut a precise recess for a 1" x 2-1/4" latch plate. Aluminum alloy holds its shape better than plastic jigs, and the kit covers both common door thicknesses. It is aimed at buyers who already own a router and want factory-clean mortises instead of chisel work.

Trade-off: It is explicitly not for strike plates, so the jamb side still needs separate handling — and the router itself is not included, which raises the real cost of this pick.

5. Child Proof Door Lock Night Flip Latch

Type: Flip latch reinforcement lock
Strength: Withstands 800 lbs
Included: 8 screws
Door fit: Inward-swinging doors only
Best for: Patio, bedroom, and front door security

Withstand 800 lbs, Child Proof Door Locks Night Top Flip Latch and 8 Screws Inward Swinging Doors Only, Defend Patio Bedroom Door Locks for Front Door Safety High Home Security Door Lock Reinforcement

Check the current price on Amazon

This flip latch mounts high on the door and flips down to brace it against forced entry, rated to withstand 800 lbs. Eight screws are included for a solid install, and the top placement keeps it out of reach of small children. It is a reinforcement layer for inward-swinging doors, not a replacement for the primary lockset.

Trade-off: It only works on inward-swinging doors, and mounting hardware into a hollow or thin door will not deliver the rated strength — the screws are only as good as the material behind them.

Before You Buy

• Measure the door thickness: Most locksets and templates are built for 1-3/8" or 1-3/4" doors, so confirm the slab before ordering.
• Check the backset: The distance from the door edge to the center of the bore hole determines whether the latch lines up; measure it on the existing lock or the new one.
• Confirm handle height: Standard height sits around the same level as the old knob, so measure center-to-center if replacing hardware.
• Match the template to the plate size: Latch plate templates are sized for specific plate dimensions, and a router jig for one size will not fit another.
• Verify door swing direction: Reinforcement latches and some lockout covers only fit doors that swing a particular way.
• Account for missing tools: A router template needs a router, and a drilling kit needs a drill — budget for the full setup, not just the jig.

Frequently Asked Questions

1. What three measurements matter most when measuring a door for a lock?
   Door thickness, backset (edge to bore center), and bore hole diameter. Get those right and most standard locksets drop in without modification.

2. Can a lock be installed without a drilling jig?
   Yes, but a guide template greatly reduces the chance of an off-center hole. For a single door, a jig is usually worth the small cost.

3. Does door thickness really change which lock fits?
   It does. Locksets and templates are built around 1-3/8" and 1-3/4" slabs, and hardware sized for one thickness may not seat properly on the other.

4. Is a flip latch a substitute for a deadbolt?
   No. It is a reinforcement layer that braces an inward-swinging door, and it works alongside the primary lock rather than replacing it.

5. Why do some lockout covers ask for a measurement before ordering?
   Because they fit over the handle’s connecting shaft, and shaft length varies between handles. A cover that does not match the shaft will not seat.

Bottom Line

For most buyers measuring a door for a lock, the Door Knob Drilling Kit is the pick that solves the problem outright — its guide template sets the bore and latch positions so the measurement happens on the door itself. Buyers working with an existing handle should start with the lockout cover instead, and anyone routing latch plates will get cleaner results from the mortise template.

Check the current price of the Door Knob Drilling Kit on Amazon