What Size Screws for a Door Hinge?

What size screw for a door hinge, by door

Where	Screw	Length	Notes
Interior door, 3-1/2 or 4 in hinge	#9 flat-head wood screw	3/4 in (19 mm)	The common size. Older hinges may use #8, so match the old screw
Exterior door	#9 or #10 flat-head wood screw	1 in (25 mm)	Sources differ on #9 vs #10. Match the old screw and the hinge's countersunk holes
Jamb side, into the stud	#9 flat-head wood screw, long	2-1/2 to 3 in (64–76 mm)	At least one per hinge, top hinge first. Lee County Sheriff's Office suggests fully threaded
Commercial 4-1/2 in hinge, metal door or frame	12-24 flat-head machine screw	1/2 in (13 mm)	Goes into the frame's tapped holes. For wood, follow the hinge maker's spec (Hager's BB1279 ships #12 x 1-1/4 in wood screws)

A 3/4 in screw only holds the hinge to the jamb, which is usually 3/4 in thick. A 3 in screw goes through the jamb and the shim gap into the framing stud.

Hinge screw gauges

Gauge	Diameter (in)	Diameter (mm)
#8	0.164	4.2
#9	0.177	4.5
#10	0.190	4.8

These are the ASME B18.6.1 wood screw diameters. The difference between them is small, so a caliper or a known screw is the easiest way to tell them apart.

How to check what your hinge needs

Take out one old screw. Measure across the threads with calipers and compare it to the gauge table.
Measure the length overall. Flat-head screws are measured from the top of the head to the tip.
Test the head in the hinge. It should sit flush in the countersunk hole. If it sits proud, go down a gauge. If it's loose and sinks below the surface, go up one.
Match the finish (satin nickel, oil-rubbed bronze, brass) if the heads show.

Fixing a sagging door

Open the door and check every hinge screw, starting with the top hinge on the jamb side. Tighten any that are loose.
If a screw spins without tightening, the hole is stripped. Fix the stripped hole first, then drive the screw again.
Swap one jamb-side screw in the top hinge for a 2-1/2 to 3 in screw into the stud. Snug it, don't crank it, and check the door still closes freely.

Common mistakes

Using pan-head, bugle-head or drywall screws. Hinges need flat-head screws that sit flush. A head that sticks up stops the door closing properly.
Going up a gauge without checking the countersink. A #10 head may not fit a hinge made for #9.
Long screws on the door side. The long screw goes in the jamb to reach the stud. The door leaf takes the standard length.
Driving into a stripped hole. Fill the hole first (a glued-in hardwood dowel works), then drill a new pilot hole.

Not sure what you pulled out? Snap it

Snap the old screw next to a ruler and Mechy tells you the size, thread and length. Test the new screw in the hinge's countersink before you drive them all. Identify a screw from a photo.

Questions

What size screws come with door hinges?

Most residential 3-1/2 in and 4 in door hinges use #9 x 3/4 in flat-head wood screws.

Can I use #10 screws in a door hinge?

Only if the head sits flush in the hinge's countersunk hole. Some exterior hinges are made for #10. If the head sticks up, the door won't close properly.

How long should door hinge screws be for security?

Long enough to reach the stud behind the jamb: 2-1/2 to 3 in. Put at least one in each hinge on the jamb side. The Lee County (FL) Sheriff's Office recommends replacing every jamb-side hinge screw and the strike plate screws with fully threaded 3 in wood screws.

What screws do commercial door hinges use?

Larger 4-1/2 in hinges on metal doors and frames use machine screws. For example, Hager's BB1279 hinge comes with 12-24 x 1/2 in flat-head machine screws and #12 x 1-1/4 in flat-head wood screws.