This size has become the standard size for modern spindles.
Standard door handle spindle size.
The standard size you need to look out for is 57mm and this is the size between the lever centre or the spindle and the lock centre and thankfully that is a very popular uk size.
Along with a large selection of door handle spindle expansion sleeves adaptors which allow a smaller spindle to be used with standard door furniture.
The standard thickness of a spindle is 7 6mm most uk latch manufacturers produce latch openings at 8mm to accommodate this.
Lever to lock size is 57mm on a typical interior locking door handle.
White polished brass rosette trim plates price.
The modern industry standard cross section thickness size of a door handle spindle is 8mm 5 16 square.
It should be noted however.
Spindles and followers were not always standardized to 8mm.
Spindle 3 1 2 inch straight spindle set with screws for old style mortise door knobs view item 42940 rosette for door knob 2 1 4 inch dia.
The majority of spindles are 9 32 square.
The center of a swivel spindle the part that ends up in the lock hubs may be fatter then the spindle ends.
You need to establish the spindle size that goes into the knob or lever and also if the center is bigger.