Solid Brass Butt Hinges: Sizes, Weights and Door Types

A solid brass butt hinge is sized by two numbers that do different jobs: its height, which carries the weight of the door, and its open width, which has to clear the door thickness and the casing. Studio Timeless offers six brass butt hinges from 3.94 to 6.22 in high, rated 88 to 110 lb per hinge, at 37 to 45 dollars each.

In short

• Six hinges in the Studio Timeless door hinge range: heights of 3.94 to 6.22 in, open widths of 2.52 to 4.09 in, 37 to 45 dollars each.
• Load ratings are per hinge: 88 lb (40 kg) on the 4 in sizes and the butterfly, 110 lb (50 kg) on the 5 in sizes and the 6.22 in round edge hinge.
• Hinge count follows door height: two up to 60 in, three above 60 in and up to 90 in, four above 90 in and up to 120 in.
• Every price is for one hinge with its screws. An 80 in door needs three, so three hinges is one door, not three.
• These are narrow-leaf hinges. Open widths of 3.03 and 2.52 in are not drop-in replacements for the square 4 by 4 in mortise common in American pre-hung doors.

What the two numbers on a butt hinge mean

A butt hinge is described by its height first and its open width second, and only the height follows the familiar sizing convention. Height runs along the barrel and is the number quoted when someone says a 4 in hinge. Open width is the dimension across both leaves laid flat, barrel included. On a classic American residential hinge the two are equal, which is why 3.5 by 3.5 in and 4 by 4 in get shortened to one number. On European-pattern narrow-leaf hinges they are not, and the second number decides whether the door can open past its own casing. Both appear on every Studio Timeless product page, in that order, and the error we see most often is reading the first number, assuming a square leaf, and planning a mortise wider than the hinge.

The six Studio Timeless brass butt hinges, measured

All six are mortise hinges supplied one per package with matching screws. The table gives published figures rather than nominal trade sizes, because published figures are what the mortise has to accept.

Two figures matter before anything else. The round edge hinge carries twelve screw holes and a 1.10 in barrel, roughly double every other barrel in the range, and the butterfly is the only model with deliberately unequal leaves, 1.57 in on the frame side and 0.94 in on the door side.

How the trade sizes a hinge to a door

The industry convention sizes hinge height from door thickness and door width together, and it is published in the selection tables that accompany the ANSI/BHMA A156.1 standard for butts and hinges. A thicker door needs a taller hinge because the leaf bears on more wood; a wider door needs a taller hinge because leverage at the latch edge is greater.

Read the last column and the shape of the range is clear. There is no 3 1/2 in and no 4 1/2 in hinge, so a narrow 1 3/8 in door under 32 in wide is over-hinged rather than correctly sized by our 4 in models, which is harmless structurally and visually heavier than some specifiers want. Above that, the range maps cleanly onto the two door thicknesses that dominate American residential work.

Open width is the dimension that fails, and there is a formula for it

Open width has to let the door swing clear of its own casing, and the trade calculates it rather than guessing. The published formula is (door thickness minus backset) times two, plus the clearance required, plus any inset, rounded up to the next standard width. Backset is conventionally 1/4 in in residential work; clearance is the swing room past the trim. Applied with a 1/4 in backset and 1/16 in clearance, the arithmetic gives a hard answer for each hinge. This is a calculation from the published formula, not a manufacturer rating, and thick or proud casing increases the clearance term.

The marginal line is the one that bites. A 3.03 in hinge on a 1 3/4 in door is 0.03 in short of the bare minimum before casing is counted, which is why we treat the 3.46 in plain hinge as the default for a 1 3/4 in door and the 3.03 in models as 1 3/8 in interior hinges. The butterfly states a minimum door thickness of 1 3/8 in on its own page, and the open width confirms it.

How many hinges a door needs

Hinge count is set by door height, with weight handled by choosing the right height and leaf thickness rather than by adding hinges. The convention published with the A156.1 selection tables is two hinges up to 60 in of door height, three over 60 in and up to 90 in, four over 90 in and up to 120 in, and one more for each additional 30 in or part of it. A standard 80 in American interior door takes three; a 96 in door takes four.

Ratings are per hinge and they do not add up. The top hinge carries the largest share, because it resists the door's tendency to rotate away from the frame, so three 88 lb hinges do not make a 264 lb assembly. Treat the per-hinge figure as a floor each hinge must clear with margin.

Working out what your door actually weighs

Door weight is volume times density, and both are knowable before the hinges are ordered. Volume in cubic feet is width times height times thickness, all in feet; density comes from the species or the core, with the USDA Forest Service Wood Handbook as the reference for solid timber. A 30 by 80 in engineered-core door at 1 3/8 in is 1.91 cu ft, about 76 lb at 40 lb per cu ft. A 36 by 80 in solid white oak door at 1 3/4 in is 2.92 cu ft, about 137 lb at 47 lb per cu ft, and the same door at 96 in tall is about 165 lb. The oak figure is the one that surprises people: a pair of 88 lb hinges is nowhere near adequate for it, while three 110 lb hinges have real margin. Treat any such number as an estimate, since glazing, a lock block, moisture content and applied moulding all move it, and the door's own specification sheet always wins.

Plain, stepped, round edge and butterfly: what the profile changes

The four profiles differ in the barrel and the leaf shape, not in how they mount. A plain hinge has a cylindrical barrel and reads as a neutral detail. A stepped hinge breaks it into a shouldered profile, a visual decision rather than a mechanical one and the reason it carries nine finishes. The round edge hinge has rounded leaf corners and a much larger barrel, for tall or heavy architectural doors. The butterfly hinge is the decorative outlier, with asymmetric leaves.

The removable pin, and when it earns its place

Only the butterfly hinge publishes a removable centre pin, and it changes how a door is hung and removed. With the pin out the leaves separate while both halves stay screwed to the door and the frame, so one person can lift a door onto its mortises, and a door can come off for painting or flooring without disturbing a screw. That matters more than it sounds: a mortise unscrewed and rescrewed several times loses thread, and worn screw holes are the commonest cause of a sagging interior door.

Mortise installation: what the cut has to achieve

All six are mortise hinges, so the leaf sits in a routed recess and finishes flush with the door edge and the jamb. Recess depth is the leaf thickness, 0.12 in on the 3 mm models and 0.14 in on the 3.5 mm models. Too deep and the door binds against the jamb; too shallow and it stands proud and the latch will not reach, and the deep cut is the harder of the two to correct. Mark from the door, cut the door mortises first, then transfer to the jamb with the door in position. Because leaf thickness differs across the range, mixing a 3 mm and a 3.5 mm hinge on one door produces a measurable twist.

Corner radius: the retrofit detail that decides everything

Existing hinge mortises come in three corner geometries and they are not interchangeable. American pre-hung doors are predominantly machined with a 5/8 in radius corner, custom millwork is usually square-cornered, and a 1/4 in radius also exists. A square-cornered hinge dropped into a 5/8 in radius mortise leaves four crescents of exposed wood; a radiused hinge in a square mortise leaves four gaps at the corners.

Our pages publish height, open width, barrel, leaf thickness, screw count and load, and they do not publish a corner radius. For new millwork that does not matter, because the mortise is cut to the hinge. For a retrofit into existing mortises it matters a great deal, and the honest answer is that it has to be confirmed before the order rather than assumed: send us the mortise dimensions and we will confirm against the actual part. We do not confirm a fit we have not verified.

Screws: what comes in the box, and what a frame needs

Each hinge ships with its own matching screws, eight on the 4 in sizes and the butterfly, ten on the 5 in sizes, twelve on the round edge hinge. They are sized for the leaf, finished to match, and correct for the door side. The frame side is where judgement comes in: on a heavy door, at least one screw per frame leaf is often specified long enough to reach the framing behind the jamb rather than stopping in the jamb, because a jamb is thin and a sagging door is almost always a frame-side failure. That is a call for the installer and the local inspector, not a spec we set from a product page. Longer brass screws are in brass screws and extensions.

Finishes: hinge names are not switch names

The door hinge range uses its own finish vocabulary, and it does not line up with the eight electrical finishes. The hinges run across Satin Gold, Polished Gold, Brushed Brass, Antique Brass, Antique Copper, Coffee, Gunmetal, Weathered Gunmetal, Bright Chrome, Satin Stainless, Matte Black, Matte Black and Gold, and Coffee and Gold, and no single hinge carries all of them: the stepped hinge has nine, the butterfly six, the round edge hinge three.

Studio Timeless electrical hardware runs on a different list, set out in full in our guide to brass light switch finishes compared side by side. Antique Brass and Matte Black appear on both; everything else does not. Do not assume a hinge finish matches a switch finish because the words look similar. Our unlacquered antique brass is a made-to-order living finish that is not returnable, and there is no unlacquered hinge at all, so a room specified in unlacquered switches will not have hinges ageing at the same rate. Brass is forgiving here: the Copper Development Association notes that copper alloys develop surface films over time, so brass tones converge rather than clash. Where an exact match matters, compare one of each under the room's own light, as with cabinet knobs and pulls and edge pulls.

The ordering trap: these prices are per hinge

Every figure on a hinge product page is the price of one hinge with its screws, and that is the most expensive misreading in this category. An 80 in door needs three, so a house with twelve interior doors needs thirty-six hinges, not twelve and not twenty-four. At 39 dollars that is 1,404 dollars, a line worth putting in a budget early. The same counting applies across the hardware range and to a kitchen's worth of cabinet knobs and pulls; whole-house projects should start from the trade programme.

What these hinges are not specified for

The range is published for interior doors, cabinets and architectural door applications, and that boundary should be read literally. None of the six is published as a ball bearing hinge; the two that state a bearing type state plain bearing, appropriate for residential frequency rather than a high-traffic commercial opening. None is published with a fire rating, so none belongs in a fire-rated assembly, where the hinge is part of a tested and labelled set and substituting a component voids the listing. None is published for exterior use. A hinge also affects how much force a door takes to open, which is regulated in accessible contexts: the ADA Standards for Accessible Design cap an interior hinged door at 5 pounds, and a hinge mortised too deep or a door that has dropped can push an opening over that line. Where a rating or an accessible opening is in scope, the specification has to come from a listed product and be measured on the installed assembly, and your local building department is the authority on what applies at your address.

Reading the hinge as part of the room

A hinge is the one piece of door hardware a visitor sees from both sides of an opening, so match within a single line of sight and allow variation room to room, exactly as with appliance pulls, extra long cabinet pulls and door stoppers. Profile carries as much weight as finish in period work: a stepped barrel reads tailored and recent, a plain barrel quieter in older interiors, the same logic as our notes on mid-century modern electrical hardware.

Frequently asked questions

What size hinge do I need for a standard interior door?

For a 1 3/8 in interior door wider than 32 in, the convention is a 4 in hinge, three per 80 in door. Our 4 in models in a 3.03 or 3.3 in open width cover that case.

Are brass door hinges sold in pairs?

No. Every Studio Timeless hinge is one hinge with its screws. Order three per standard 80 in door and four per 96 in door.

How many hinges does a door need?

Two up to 60 in of door height, three over 60 in and up to 90 in, four over 90 in and up to 120 in, plus one more for every additional 30 in or part of it.

How much weight can a brass butt hinge hold?

The 4 in models and the butterfly are published at 88 lb (40 kg) per hinge, the 5 in models and the round edge hinge at 110 lb (50 kg), subject to correct installation and a suitable door and frame.

Can I replace my existing hinges without recutting the mortise?

Only if height, open width, leaf thickness and corner geometry all match what is already cut. We publish the first three and not the corner radius, so send us your mortise dimensions and we will confirm before you order.

What is the difference between a plain and a stepped butt hinge?

The barrel profile. A plain hinge has a cylindrical barrel, a stepped hinge a shouldered one. Both mount identically in a mortise, so the choice is visual.

Do these hinges work on a 1 3/4 in door?

The 3.46 in plain hinge and the 4.09 in round edge hinge do, with real clearance. The 3.03 in models are marginal before casing is counted, and the 2.52 in butterfly is not suitable.

Which hinge lets me take the door off without unscrewing it?

The butterfly hinge, which publishes a removable centre pin. Pull the pin and the leaves separate while both halves stay fixed.

Can I use these on an exterior door?

They are published for interior doors, cabinets and architectural applications. An exterior or fire-rated opening needs a hinge listed for that use, and your building department is the authority.

Will the hinges match my brass light switches?

Not by name. The hinge finishes and the eight electrical finishes are separate lists with only Antique Brass and Matte Black in common, and there is no unlacquered hinge. Compare one of each in the room.

How deep should the hinge mortise be?

The leaf thickness: 0.12 in on the 3 mm models and 0.14 in on the 3.5 mm models, so the leaf finishes flush with the door edge.

Why is my brass door sagging after a few years?

Almost always the frame-side screws rather than the hinge. Screws that stop in a thin jamb, or holes stripped by repeated removal, let the top hinge pull forward; reaching the framing behind the jamb on one screw per frame leaf is the usual remedy.

Choosing in one line

For 1 3/8 in interior doors, a 4 in hinge in a 3.03 or 3.3 in open width; for 1 3/4 in doors, the 3.46 in plain hinge in 5 in; for tall or heavy architectural doors, the 6.22 in round edge hinge. Count three per 80 in door and four per 96 in, and read the installation and compatibility guide before cutting anything. The full range is in brass door hinges.

Last updated: October 1, 2026