Threaded Rubber Feet: Thread Size Guide (1/4-20, 5/16-18, M8)

Find your thread in 30 seconds: measure the stud or bolt diameter, count threads in 1/2" and double it (or read the pitch with a gauge), then match the row below. Jump to thread chart · look-alike threads · in-stock threaded feet.

Threaded rubber feet screw straight onto a bolt or into a threaded hole: leveling feet on machines and furniture, replacement feet on amplifiers, printers and appliances, and anti-vibration feet under motors and compressors. Getting the thread right is the whole job; diameter and height come second (see the rubber feet sizing guide).

Thread size chart

Thread	Diameter	Metric	Threads per inch	In stock now
#6-32	0.138"	3.5 mm	32	4
#8-32	0.164"	4.2 mm	32	2
#10-32	0.190"	4.8 mm	32	3
1/4-20	0.250"	6.35 mm	20	23
M6 x 1.0	0.236"	6.0 mm	25.4 (1.0 mm pitch)	3
5/16-18	0.3125"	7.9 mm	18	22
M8 x 1.25	0.315"	8.0 mm	20.3 (1.25 mm pitch)	2
3/8-16	0.375"	9.5 mm	16	2

How to identify the thread

Diameter: measure across the threads of the stud, or the bolt that goes into the foot. Under 0.2" it is a numbered machine screw (#6, #8, #10); 1/4" and up is a fractional size.
Pitch: count the thread crests along 1/2" with a ruler and multiply by two for threads per inch. Twenty per inch on a 1/4" stud is 1/4-20; eighteen on a 5/16" stud is 5/16-18.
Male or female: a stud sticking out of the rubber is male; a threaded metal insert in the rubber is female.
Stud length: measure only the threaded part, not the rubber.

Look-alike threads that do not interchange

Inch	Metric look-alike	How to tell
1/4-20	M6 x 1.0	20 vs about 25 threads per inch
5/16-18	M8 x 1.25	18 vs about 20 threads per inch
#10-32	M5 x 0.8	Almost the same pitch (32 vs 31.75 per inch), but M5 is 0.197" across vs 0.190"; try a known nut

In-stock threaded rubber feet and mounts

#6-32 threaded feet

#8-32 threaded feet

#10-32 threaded feet

1/4-20 threaded feet

M6 x 1.0 threaded feet

5/16-18 threaded feet

M8 x 1.25 threaded feet

3/8-16 threaded feet

Mounts with studs on both ends are listed in the vibration mount size chart. Feet that screw on through a hole instead of a thread are in the screw size table.

FAQ

How do I tell 1/4-20 from M6?

They are only 0.014" apart in diameter, but the threads differ: 1/4-20 has 20 threads per inch (about 1.27 mm pitch), M6 has 1.0 mm pitch (25.4 per inch). Hold the stud against a known 1/4-20 bolt: if the threads don't nest exactly, it's metric. Don't force one into the other; it strips the insert.

Is 5/16-18 the same as M8?

No. They are close in diameter (7.9 mm vs 8 mm) but 5/16-18 is about 1.41 mm pitch and M8 coarse is 1.25 mm. American equipment usually uses 5/16-18; European and Asian machines usually use M8.

What length stud do I need?

For a threaded hole, the stud should be about 1/16" shorter than the hole is deep. For a through hole with a nut, add the panel thickness, a washer and the nut height, plus two threads showing.

Male stud or female insert?

Choose a male stud when the equipment has a threaded hole or a through hole for a nut. Choose a female threaded foot when the equipment has a bolt or threaded rod sticking down, such as many leveling legs.

Threaded Rubber Feet Size Guide: 1/4-20, 5/16-18, M6 & M8