Door hinge mortise and placement
For a mortised butt hinge in a jamb. The outer two sit at fixed distances that have nothing to do with the door's height, which is what makes the layout worth knowing rather than measuring twice.
= 1.375"
Use
3× 3 1/2" hinges
Mortise depth
0.085"
Top hinge, from the top
5"
Bottom hinge, from the bottom
10"
Where to buy this
- 3 × 3 1/2" butt hingesHome DepotLowe'sAmazon
Sold in pairs or singly depending on the maker, and square-corner against radius-corner has to match your existing mortises if you are replacing rather than hanging new.
Plain search links, nothing sponsored. Prices and stock are the shop's, and a local lumberyard will usually beat both on solid stock.
Marking out, from the top of the door
- Hinge 15" down from the top of the door
- 5" to 8 1/2"
- Hinge 2Spread between the outer two
- 35 3/4" to 39 1/4"
- Hinge 310" up from the bottom
- 66 1/2" to 70"
Measured to the ends of the leaf, not to its centre — which is what the 5"-and-10" convention means.
Why 5 and 10 rather than evenly spread
The bottom rail of a panelled door is wider than the top rail, and a hinge screwed into the joint between rail and stile is a hinge screwed into end grain. Five down and ten up put both leaves in solid stile. It also means the middle hinge is not halfway down the door: it is centred between the outer two, which on an 80" door is 35 3/4" rather than 40".
Count is one hinge per 30" of height with two as the floor. Size comes off thickness and width instead, because the leverage pulling the screws out of the jamb grows with how far the door's weight sits from the hinge.
Cut the mortise shy rather than deep
The mortise is exactly as deep as the leaf is thick. Too shallow and the door will not close — the two leaves bind and push it back out of the frame. Too deep and it binds the other way, straining the screws every time it shuts. A hair proud of flush is the right error to make, because a hinge can be shimmed out and a mortise cannot be un-cut.
Butt hinge sizes
- 3"Light interior doors and small cupboards up to about 24" wide.
- 0.079" leaf
- 3 1/2"The standard 1 3/8" hollow-core interior door up to 36" wide.
- 0.085" leaf
- 4"1 3/4" solid-core and exterior doors up to 36" wide.
- 0.134" leaf
- 4 1/2"1 3/4" doors over 36" wide, and heavy doors on a closer.
- 0.134" leaf
- 5"Doors over 42" wide or over 2" thick — commercial weight.
- 0.19" leaf
Convention and manufacturer practice, not code. A fire door, a commercial opening or anything carrying a closer is governed by its own listing and hardware schedule. For a cabinet door on concealed European hinges, the cabinet hinge calculator is the one you want — those are spread evenly and need no mortise at all.
About hanging a door
- Where do door hinges go?
- Top hinge 5" down from the top of the door to the top of the leaf, bottom hinge 10" up from the bottom to the bottom of the leaf, and a third centred between them. The asymmetry looks like a mistake and is not: the bottom rail of a panelled door is wider than the top rail, and five and ten put both leaves in solid stile rather than across the joint between rail and stile, which is end grain.
- Isn't the middle hinge just halfway down the door?
- No, and this is where laying it out by eye goes wrong. It is centred between the outer two hinges, and because the bottom setback is the bigger of the two, that centre sits above the door's own halfway mark — on an 80" door it belongs at 35 3/4", not 40".
- What size butt hinge do I need?
- 3 1/2" for a standard 1 3/8" interior door, 4" for a 1 3/4" solid-core or exterior one, and 4 1/2" once that door is over 36" wide. Thickness sets the floor and width can raise it, because the leverage trying to pull the screws out of the jamb grows with how far the door's weight sits from the hinge. Height sets the count instead — one hinge per 30" of door, two at a minimum.
- How deep should the mortise be?
- Exactly the thickness of the leaf, which is 0.085" for a typical 3 1/2" hinge and about 0.134" for a 4". Too shallow and the door will not close — the two leaves bind and push it back out of the frame. Too deep and it binds the other way, straining the screws every time it shuts. A hair proud of flush is the right error to make, because a hinge can be shimmed out and a mortise cannot be un-cut.
- Is this the same as a cabinet hinge calculator?
- No — that is a different page on this site. A cabinet door on concealed European hinges has its hinges spread evenly and needs no mortise at all, just a 35mm cup bore. This one is for a mortised butt hinge in a jamb, where the placement is a fixed convention rather than an even division. None of it is code, either: a fire door or anything on a closer is governed by its own listing and hardware schedule.
You might also need
- Cabinet hinge count and placementHinge count from door height, and where each one sits down the door.
- Cabinet boxesA carcass cut list from the finished outside dimensions, face-frame or frameless.
- Tap and clearance drillsThe drill for a machine screw or a threaded insert, and the clearance hole in the piece it passes through.