Which hardware does my interior door need? Handle, lock and hinges

on Oct 10, 2026

in Building Materials & DIY, DIY Guides & Building Tips

Which hardware does my interior door need? Handle, lock and hinges

A new door handle, a lock that sticks or a door that slams without a stopper: the door hardware determines how nicely an interior door works and how it looks. But which hardware fits your door? This blog explains which parts there are, how to take the measurements (door thickness, backset, left or right hand) and which choice suits where.

What do you need to choose and fit door hardware?

Which materials do you need?

The hardware itself: door handles with plates, a lock, hinges and, if needed, a door stopper and draught strip. Not sure which ones fit? Ask us via contact. We are happy to help you with the right measurements.
Suitable screws for handle plates and hinges, usually supplied. If they are too short or too thin, choose wood screws such as hardened screws for wood and chipboard.
An old lock or handle as an example: keep it at hand and you can see straight away whether the sizes match.

Which tools do you need?

A tape measure, a folding wooden ruler or a tape measure with auto-lock to measure the door, its thickness and the distances.
A square and a carpenter’s pencil to mark the position of the lock and handle hole at right angles, and a level to check the handle height.
A screwdriver set or an 8-piece screwdriver set to remove old hardware and fit new; it goes faster with a cordless drill driver.
A wood chisel set to trim the lock mortise or tidy a recess.
Protective equipment: work gloves, safety glasses and knee pads if you work at the bottom of the door. Choose your own size.

Which hardware does an interior door have?

Door handle and door furniture

The door handle operates the lock. A handle usually comes as a pair with a square spindle that passes through the lock. You choose between a pair on rosettes or on long plates, and between a handle on both sides or a handle with a blind plate or knob on one side. Check that the pair suits the thickness of your door.

Plates: rosettes or long plates

A rosette is a round or square plate around the handle; a long plate is a long plate that also covers the keyhole or lock cut-out. Rosettes are simple and clean. Long plates hide old holes from a previous lock and give the door extra protection because the handle wears it less.

Which lock suits which door?

Latch (non-locking): the door closes with a bevelled latch and stays shut without a key. This is the standard for bedrooms, hallways and living rooms.
Toilet lock (vacant/occupied): a lock with a slide or turn knob on the inside, without a key. It is operated from the inside handle, with an emergency release on the outside. Handy for the toilet and bathroom.
Bathroom lock: similar to the toilet lock; choose a moisture-resistant version with a slide or turn knob, often with an emergency release.
Cylinder or key lock: for rooms you really want to lock, such as a study or utility room.

Hinges

Interior doors hang on two or three hinges. Choose the size, thickness and finish to suit the existing frame and the weight of the door. A third hinge in the middle prevents sagging on a heavy door. How to cut the recesses is described in our blog how to cut hinge recesses in an interior door.

Door stopper

A door stopper prevents the handle from knocking a hole in the wall. There are floor stoppers, stoppers for the skirting board or wall and hooks that hold the door against the wall. Position it so that the door hits the stopper before the handle hits the wall, and pay attention to the floor or skirting finish.

Threshold and draught strip

Under an interior door you can fit a draught strip or drop seal to reduce draughts, noise and dust. Allow for the gap between the door and the floor: a strip that sits too low will scrape the floor. In bathrooms and for doors with a ventilation grille, air should be able to pass; don’t seal that gap.

Finish: colour and material

Hardware comes in many finishes, such as stainless steel, black, white, brass and bronze. Keep one colour and finish throughout the house (handle, plates and hinges) for a calm look. Stainless steel and black hardware are low-maintenance; brass has a warm look but develops a patina over time. If you are painting the door, let it dry before the hardware goes back on: read how to paint a door.

Which measurements should you take?

Door thickness: most interior doors are about 38 to 40 mm thick. Measure the thickness at the edge and choose a handle pair and lock that match.
Backset: the distance from the edge of the door to the centre of the square hole for the handle. Common sizes are 50 and 55 mm. Measure it on the old lock or the handle hole.
Square spindle: many handles have an 8 mm spindle. Check that the spindle is the right length for the thickness of your door.
Handle height: usually about 1 metre above the floor. Use a level to keep the handle straight.
Screw hole spacing: for long plates (the distance between the holes for handle and lock), measure on the old hardware.

Left-hand or right-hand door?

Stand on the side the door opens towards you. If the hinges are on the left, it is a left-hand door; on the right, a right-hand door. Many locks and handles are reversible, but not all, so make a note. With a toilet or bathroom lock, it can also matter which side the emergency release is on.

A white door with glazed panels and a door handle — Photo: Abdullah Öğük via Pexels

Which choice suits where?

Living room, bedroom, hallway: latch with a handle pair on rosettes or long plates.
Toilet: toilet lock with vacant/occupied, handle on rosettes or long plates.
Bathroom: bathroom lock with emergency release; choose moisture-resistant hardware in stainless steel, black or white.
Office or study: key lock for privacy.
Heavy or wide door: three hinges and a sturdy handle pair.
High-traffic spot or children: door stopper and a rounded handle without sharp edges.

How do you fit a door handle with lock, step by step?

Measure the door. Note the thickness, backset and swing direction and check that the handle and lock suit them.
Mark the height. Measure about a metre from the floor, draw a line with the square and pencil and check it with the level.
Make the cut-out. If a lock mortise already exists, there’s nothing to do. For a new door, drill the hole for the handle and cut the mortise for the lock; work carefully and use a chisel for the last few centimetres. Have a professional do this if in doubt.
Fit the lock. Slide the lock into the mortise with the latch facing the closing side of the door. Fix the lock with the screws of the face plate.
Fit the handle. Pass the spindle through the lock, slide the handles and plates onto the spindle on both sides and tighten the screws with the screwdriver or cordless drill driver.
Test the lock. Check that the latch moves in and out smoothly and the door closes properly. Adjust the strike plate in the frame if needed.

Close-up of a door knob on a door in soft light — Photo: Chris F via Pexels

What mistakes do DIYers often make?

Not measuring the backset. A lock with the wrong backset does not fit the cut-out in the door.
A spindle that is too short. The handle then won’t stay put. Check the thickness of the door.
Forgetting the swing direction. A lock or handle for left doesn’t always work on a right-hand door.
Fitting a door stopper too late. The handle has already knocked a hole in the wall.
Not pre-drilling screws. The wood can split, especially at the edge of the door.

💡 Tip: take a photo of the old hardware and measure the lock before you unscrew the handle. That way you have all the dimensions to hand when you buy new hardware.

How do you stay safe when fitting door hardware?

Wear work gloves when handling sharp metal parts and safety glasses when drilling and chiselling. Working at the bottom of the door or at the floor stopper? Knee pads will spare your knees. You can find all personal protective equipment in our workwear and safety category. Read more tips in our guide safe working on the construction site. With fire-rated doors, doors with built-in closing mechanisms or your front door: if in doubt, call a professional.

What do DIYers often ask about door hardware?

What is the difference between a latch and a toilet lock?

A latch closes the door with a latch bolt but can’t be locked. A toilet lock has a slide or knob on the inside to lock the door, and an emergency release on the outside.

How do I know which backset I need?

Measure the distance from the edge of the door to the centre of the square hole for the handle. Common sizes are 50 and 55 mm. If in doubt, measure the old lock.

How do I know whether I have a left-hand or right-hand door?

Stand on the side the door opens towards you. If the hinges are on the left it is a left-hand door; if they are on the right, it is a right-hand door.

Can I replace rosettes with long plates?

Often yes, but watch the spacing between the holes and the hole for the lock. Long plates cover larger holes, but only fit if the distance between the handle and cylinder holes matches.

How high should I hang the door handle?

Usually about 1 metre above the floor. Look at the height of the other doors in your home so everything stays level.

When is it better to call in a professional?

With a fire-rated or burglar-resistant door, a door with a built-in lock you don’t know, if a lot of wood has to come out for a new mortise, or if you simply don’t have the time or the inclination.

More DIY tips for your interior door

Working on more than one part of your door? Then also read: How to paint a door and How to cut hinge recesses in an interior door.

Where can you find everything for door hardware for your interior door?

At Saniso, the online DIY and building store, you’ll find tools and personal protective equipment for your job. Questions about door hardware or hinges? Feel free to ask us.