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.

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.

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. Print each hinge's own mortise template at true size below.

Door height

Door width

Door thickness

= 1.375"

Use

3× 3 1/2" hinges

Mortise depth

0.085"

Top hinge, from the top

Bottom hinge, from the bottom

10"

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.

Mortise templates, at true size

Each hinge's own leaf length, not the whole door — the long distance down from the top is a tape measurement, and the leaf length is the part worth printing. Print at 100%, check the ruler, then hold each strip against the door edge starting at its own distance from the top.

Check this first

Put a tape on the printed ruler. If it does not read exactly 6 inches, the print was scaled — set the print dialog to 100% or “Actual size” and print it again. Do not cut wood from a template that failed this.

Hinge 1, 3 1/2" leaf

Starts 5" down from the top of the door edge (5" down from the top of the door). Mortise depth is 0.085", set with a marking gauge rather than measured off paper.

Hinge 2, 3 1/2" leaf

Starts 35 3/4" down from the top of the door edge (Spread between the outer two). Mortise depth is 0.085", set with a marking gauge rather than measured off paper.

Hinge 3, 3 1/2" leaf

Starts 66 1/2" down from the top of the door edge (10" up from the bottom). Mortise depth is 0.085", set with a marking gauge rather than measured off paper.

Printing this properly

In the print dialog, set the scale to 100% or “Actual size” and turn off “Fit to page”. Measure the printed ruler with a tape before you trust a leaf length — a hinge mortise cut a sixteenth short binds the door every time it closes.

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.

Where to buy this

3 × 3 1/2" butt hingesHome Depot Lowe's Amazon

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.

Worked example: an 80" door

An 80" × 32" × 1 3/8" door takes three 3 1/2" butt hinges, each mortised 0.085" deep.

The top hinge starts 5" from the top and the bottom one ends 10" from the bottom, which keeps both leaves out of the rail joints. Marked from the top of the door, to the ends of each leaf:

Hinge 1: 5" to 8 1/2"
Hinge 2: 35 3/4" to 39 1/4"
Hinge 3: 66 1/2" to 70"
Mortise depth: 0.085"

These are the figures the calculator above opens on. Change any field and it works the same problem for your numbers.

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.