# Forum Home Renovation Doors, Windows, Architraves & Skirts  whats the normal hole size for door lock sets?? 54mm? 52mm? or what?

## wozzzzza

i need to go out and get some new door locks, them privacy ones you have on bedrooms, round ball shaped handles with a little push button on the inside to lock it.
i have a new door i need to fit them to, what size holes do i need for this??
i ahve a hole saw of 52mm and 57mm, but hte instructions online seem to say i need a 54mm hole. what im wondering is does it really matter if its 52mm or wont it fit??
and what size does the knib thing need to be to fit?? i have a 25mm spade bit.

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## Ozcar

I installed two locks about a year ago.  
The one was similar to the one you describe, but with a key on on one side. The instructions said a 50mm hole was needed, but I was replacing an existing lock and the hole was a fair bit bigger, it could have been 55mm, but there was no problem.  
The other, a deadlock, came with instructions saying a 54mm hole was required, but I only had 50mm and 57mm hole saws. I used the 50mm one figuring that if necessary I would hack the hole bigger one way or another, but it turned out that the 50mm hole was big enough. 
Your mileage may vary, but it seems that there is quite a bit of tolerance in the hole sizes. 
The strike needed a 1inch/25mm hole.

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## wozzzzza

cool, so i wont bother getting a new hole saw then.
thanks.

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## Bloss

The actual answer is you can't know for sure until you get the lockset and can measure what has to fit through the hole! There are no 'standard's' for this, just various commonly used sizes - and too mnay uncommonly used fittings! 
The space is for the lock core and usually for the screws that hold the two sides together. Sometimes 2mm overall won't matter, sometimes it will. Mostly the issue will be just the space for the long fixing screws so any adjustment will be simply to allows for them - a good thing as taking a hole from 50mm to 52mm or 54mm or 57mm is a right PITA! In a new door don't drill until you have the hardware and drill the size they say, if plan on not doing that then measure and check, twice. It might be smarter to drill the next size up, but _only_ if the flange covers that area well enough. As I said check before you drill. 
Likewise matching fittings to old cut-outs needs care for this reason and of course because set-backs (from edge of door to centre of lock handle) vary widely too! Ah gotta love 'choice'.

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## wozzzzza

thats what i did, didnt drill until i had the lock set, not going to fall into that trap. lockset said 54mm, but fit perfectly with 52mm.
but i still can never work out what the 60 and 70mm backset is all about or what one to do, i just did 60mm.

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## sharpy

> thats what i did, didnt drill until i had the lock set, not going to fall into that trap. lockset said 54mm, but fit perfectly with 52mm.
> but i still can never work out what the 60 and 70mm back-set is all about or what one to do, i just did 60mm.

  The back-set refers to how far from the front edge of the door to the center of the handle the distance is.  
Standard is 60mm. In some cases you might use 70mm( or even more-but that's unlikely in residential houses) where you might just need that extra clearance  between the handle and the door frame.  
For example, not long ago I had to install a new handle to a bathroom entry door, but the door frame wasn't standard and the handle was scraping the doorjamb every time you shut the door, so making it 70mm back-set did the trick and the that 10mm clearance was just enough. 
Hope it helped. 
Regards, Sharpy

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## wozzzzza

> The back-set refers to how far from the front edge of the door to the center of the handle the distance is. 
>  where you might just need that extra clearance  between the handle and the door frame.   
> Hope it helped. 
> Regards, Sharpy

   ah got it, so the handle is installed in the door at installation time to suit 60 or 70 for the frame clearance.
cool.

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