Lever Door Handle Backset Sizes: 70mm, 85mm, 92mm Explained

Choosing the right lever door handle is one of the simplest but most important decisions when fitting internal doors. A key measurement that determines compatibility is the backset: the distance from the edge of the door to the centre of the spindle or keyhole. This guide explains the three most common backset sizes used in the UK – 70mm, 85mm, 92mm – and helps tradespeople and DIY enthusiasts select and install the correct lever door handle for the job.

What is a backset and why it matters

The term backset refers to the horizontal measurement from the face of the door (the edge the latch sits in) to the centre of the handle spindle or cylinder. It is crucial because the wrong backset will mean the spindle does not line up with the latch mechanism; the handle will either not operate the latch or the escutcheon will not cover the cut-out neatly.

When specifying or ordering a lever door handle, always confirm the backset to ensure:

• the spindle engages the latch correctly
• the handle roses or backplates sit flat on the door
• the aesthetic proportions match the door and lock case

Common backset sizes: 70mm, 85mm, 92mm explained

Most UK doors use one of three backset sizes. Knowing their typical applications helps choose the right lever door handle faster.

• 70mm backset – Common on older internal doors and some narrow stile doors; often used with smaller tubular latches. If you are replacing an existing handle on an older property, measure first as 70mm was more prevalent historically.
• 85mm backset – A mid-range size that suits many modern internal doors and fire doors. It is versatile and often found on commercial-style locks and multipoint mechanisms; a good choice for retrofit projects where the exact original size is unclear.
• 92mm backset – The current standard for many new doors in the UK, especially pre-hung doors and doors fitted with standard latch cases. If you are installing a new door or fitting a replacement latch, 92mm is frequently the default specification.

How to measure the backset correctly

Accurate measurement is essential. Follow these practical steps to measure the backset so you can order the correct lever door handle:

1. 1Close the door and locate the edge where the latch protrudes.
2. 2Measure from the edge of the door to the centre of the spindle hole or the keyhole; this is the backset.
3. 3If the latch is already fitted, measure to the centre of the square spindle hole on the face of the latch.
4. 4Double-check the measurement in millimetres and note whether the door has a face-fixing or concealed latch, as this may require different handle types.

Tip: If you cannot measure on-site, remove the latch or lock case and measure from the faceplate to the spindle hole for the most accurate reading.

Matching the lever door handle to the lock case or latch

When selecting a lever door handle, consider the interaction between the handle, spindle and latch. Key points include:

• Spindle length: Ensure the spindle supplied with the handle will pass through the door thickness and engage the lever mechanism properly.
• Square spindle sizes: Common sizes are 7mm or 8mm; check the latch centre and handle specifications before ordering.
• Backset compatibility: Handles are often specified for a particular backset; some lever sets can be adjusted to suit multiple backsets, but many are fixed to 70mm, 85mm or 92mm.
• Latch faceplate size and cut-out: Make sure the new handle and latch faceplate match the existing mortice so minimal modification is needed.

Practical considerations for tradespeople and DIY installers

On-site realities often influence the choice of lever door handle more than theory. Consider these practical tips:

• Always carry a small selection of commonly used latches and fixings for 70mm, 85mm and 92mm applications; this avoids repeat visits.
• For retrofit jobs, measure rather than guess; a 2mm discrepancy can make a handle non-functional or look misaligned.
• When replacing handles on fire doors or commercial doors, check the relevant standards and whether the latch or lock must be CE marked or fire-rated.
• Document the door thickness as well; lever door handle sets designed for thicker doors require longer fixings and spindles.

Installation tips and troubleshooting

Follow these steps to install a lever door handle correctly and avoid common faults:

1. 1Confirm the backset and choose a matching lever door handle.
2. 2Fit the latch or lock case first; ensure it is set square and the faceplate is flush with the door edge.
3. 3Insert the spindle and temporarily fit the levers to check smooth operation and alignment.
4. 4Tighten fixings evenly; if roses or backplates sit proud, adjust the spindle length or use packers designed for the handle set.
5. 5Operate the handle several times to ensure the latch retracts fully and the handle returns to its neutral position without catching.

Common problems include misaligned spindle holes, incorrect spindle length and using a handle designed for a different backset; measuring and pre-checking remedies most issues.

Choosing the correct lever door handle comes down to accurate measurement and understanding the relationship between the handle, spindle and latch. For most modern doors 92mm is common; 85mm suits many commercial and retrofit scenarios while 70mm appears on older or narrow stile doors. Tradespeople who carry a range of latches and follow the measuring and installation steps above will save time and ensure reliable, professional results.

For further guidance, consult our pillar guide on door handles at /guides/door-handles or contact our trade support team for help specifying the right lever door handle for your project.

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