How to Measure Door Hinges for Replacement: Size, Corner Radius & Finish
A door can start to scrape the jamb, sag at the latch side, or refuse to stay open. The hinge may be the culprit, but a replacement hinge only works when it matches the old one. A hinge that looks close in a product photo can still have the wrong width, corner shape, or screw-hole pattern.
For a clean door hinge replacement, measure the hinge that is already on the door before you shop. Record its open size, corner radius, hole layout, finish, and bearing type. Those details tell you far more than the door's label or a guess based on the room.
Table of Contents
- Read the old hinge before buying a new one
- Measure the hinge with both leaves open
- Match the corner radius to the existing mortise
- Count screw holes and compare their layout
- Choose the size from the door that is in front of you
- Finish and bearing type come after the fit
- Install only after the new hinge passes a dry fit
- Door hinge replacement FAQ
Read the old hinge before buying a new one
Start with the hinge you are replacing. Take a clear photo of it while it is still mounted, then support the door and remove one hinge only if you need a closer look. Do not pull every hinge at once unless the door is properly braced. A single loose hinge gives you the measurements without turning a small repair into a door-support problem.
Lay the hinge flat on a table and note what you see. Is the leaf square at the corners or rounded? How many screw holes are on each leaf? Is there a visible bearing between the knuckles? Put these notes in your phone along with the measurements. They are useful once the old hinge is off the door and every dark bronze or satin nickel sample starts to look alike.
| Check | What to record | Why it matters |
|---|---|---|
| Open hinge size | Height by width, with both leaves fully open | The leaves need to cover the existing mortises. |
| Corner radius | Square, 1/4-inch radius, or 5/8-inch radius | A different corner shape leaves gaps or requires woodwork. |
| Screw-hole pattern | Hole count and the position of each hole | Matching holes keeps the replacement from creating new damage. |
| Finish and bearing | Existing finish and any bearing between the knuckles | These affect the finished look and the hinge style you compare. |
Measure the hinge with both leaves open
Door hinge size is written as height by width. Open the old hinge flat, then measure from the top edge to the bottom edge for the height. Measure from one outside edge to the other for the width. A common label is 3.5 in. x 3.5 in. or 4 in. x 4 in.
Do not measure the hinge while it is folded. The folded measurement misses half the width, which is exactly the dimension that must sit in the old mortise on the door and frame. A steel tape or ruler is enough; measure to the nearest 1/16 inch if the hinge is not an obvious standard size.
Many interior residential doors use a 3.5-inch hinge, while 4-inch hinges are common on exterior doors and heavier doors. Treat that as a starting point, not a buying rule. The hinge already on the door is the part that has to fit.
Match the corner radius to the existing mortise
Look at the corners of the hinge leaf and the recess cut into the edge of the door. The common options are square corners, 1/4-inch radius corners, and 5/8-inch radius corners. A square-corner hinge does not sit flush in a rounded mortise. A rounded hinge leaves exposed space in a square mortise.
If the curve is hard to judge by eye, compare it with the old hinge rather than relying on a product image. A 1/4-inch curve is close to the curve of a dime, while a 5/8-inch curve is broader, closer to a quarter. This is only a quick check. The old hinge and the cutout in the door are the final reference.
Corner radius is easy to overlook because the difference is small. It is also the detail most likely to turn a five-minute swap into trimming, filling, and repainting. Match it first.
Count screw holes and compare their layout
Hinge height and width are not enough. Count the holes on each leaf, then compare where they sit. Two hinges can share a 3.5-inch size and still place the screws differently. If the holes do not line up, the screws can miss the old pilot holes or sit too close to the edge of the mortise.
Use your photo and place the replacement over the old hinge before installation. The new leaf should cover the old outline, and its holes should align without forcing the screws. If you are replacing multiple hinges, check every one. Previous repairs sometimes leave a mismatched hinge in the middle of the door.
Choose the size from the door that is in front of you
Exterior, fire-rated, solid-core, and high-use doors can need a different hinge than a light interior hollow-core door. Door thickness, weight, and the number of hinges matter. But the first job is still physical fit: match the existing leaf size, corner radius, and screw pattern before deciding that a larger hinge must be better.
For a typical residential replacement, compare the measurements against the options in our door hinges collection. The collection includes common 3.5-inch and 4-inch options with different corner shapes and finishes. Check each product page for its stated dimensions and application before adding it to your cart.
Finish and bearing type come after the fit
Once the hinge fits the mortise, choose a finish that works with the nearby lever, lockset, and other exposed hardware. Matte black makes a strong outline on a light door. Satin nickel is a quieter match for brushed nickel hardware. Oil-rubbed bronze and brass work best when the rest of the room already carries that warmer metal family. The hinge does not need to match every metal in the house, but a random finish on the door edge is more noticeable than people expect.
Check the knuckles before choosing a bearing type. A standard butt hinge has interlocking knuckles around a pin. A ball-bearing hinge has bearings between those knuckles and is usually chosen for a heavier door or a door that opens many times a day. Do not choose bearing type before the hinge size and corners are settled. A ball-bearing hinge with the wrong mortise shape is still the wrong hinge.
Install only after the new hinge passes a dry fit
Set the new hinge into the empty mortise before you drive any screws. The leaf should sit flat, the corners should meet the cutout cleanly, and the barrel should clear the edge of the door. Start screws by hand so you can catch a mismatch early. If the hinge rocks, leaves a gap, or pulls the door out of alignment, stop and recheck the dimensions rather than tightening harder.
A replacement hinge should disappear into the old mortise. If you need to trim wood, move every screw hole, or force a rounded leaf into a square recess, the measurements do not match.
Door hinge replacement FAQ
How do I know what corner radius door hinge I need? +
Remove one old hinge or inspect the mortise closely. Match square corners, 1/4-inch radius corners, or 5/8-inch radius corners to the existing cutout. The old hinge is more reliable than a visual guess from a listing photo.
Should I choose a 3.5-inch or 4-inch door hinge? +
Measure the old hinge fully open. A 3.5-inch hinge is common on many interior doors, and a 4-inch hinge is common on exterior or heavier doors, but the existing mortise and screw-hole pattern decide the correct replacement.
Can I replace a square-corner hinge with a rounded-corner hinge? +
Not as a direct drop-in replacement. A rounded hinge leaves visible gaps in a square mortise, and a square hinge will not sit flat in a rounded one. Match the corner shape to avoid altering the door or frame.
Do I need ball-bearing door hinges? +
Ball-bearing hinges are often selected for heavier or frequently used doors. First confirm the hinge size, corner radius, and hole pattern. Then compare the product description to the weight and use of your door.