Turntablism
33 and 45 rpm
Records are cut for one of two rotation speeds: 33⅓ rpm, which fits more music per side, or 45 rpm, which uses more groove per second and so carries more detail and level. The deck must match the pressing.
In practice
Wrong speed is the fastest fault to hear and to fix. Twelve-inch club pressings are 45 more often than people expect.
Check the label before you drop the needle: the speed is almost always printed, and the shape of the groove is a decent second clue — a single track filling a whole twelve-inch side is very likely 45. Playing at the wrong speed does no damage, so it is a mistake with no cost beyond the ten seconds of it happening in a room. Note that a deliberate speed change is a real technique: a 45 played at 33 is one way to reach a much slower tempo than the pitch fader alone allows.
33⅓
More music per side
45
More groove per second
The label
Where it is printed
Where these come from: The two standard record speeds and their trade-off — format definitions, not catalog figures. For what we can measure, see the other way to change tempo.
Why it matters
It is the most immediately audible mistake in DJing. A 45 played at 33 is slow, dark and obviously wrong; a 33 played at 45 is fast and thin. Both are recoverable in a second if you know which control to reach for, which is the entire practical content of the distinction.
The choice also explains a lot about twelve-inch singles. Cutting a single track at 45 across a whole twelve-inch side gives it the widest, loudest groove available, which is why club pressings so often use it and why they sound bigger than the same track on an album.
Frequently asked
How do I know if a record is 33 or 45?+
It is almost always printed on the label. A twelve-inch with a single track per side is very likely 45, because that is the point of cutting it that way.
Does playing at the wrong speed damage a record?+
No. It sounds obviously wrong and nothing else happens, so it is a mistake with no cost beyond the seconds it is audible.
Why do 45s sound better?+
More groove passes the stylus per second, so there is more room for detail and level. That is also why they fit less music per side.
Related terms
Turntable
A turntable spins a record at a constant speed while a stylus tracks its groove. A DJ turntable adds a pitch fader, high torque so it reaches speed instantly, and a platter you can hold and release.
Pitch fader
The pitch fader is the slider that speeds a track up or slows it down, usually by up to 6 or 8 percent. It is how two records are brought to the same tempo before they are mixed.
45 adapter
A 45 adapter fills the large centre hole found on many seven-inch singles so they sit on a standard spindle. Some are a small disc that drops in; others are a full platter-sized puck.
Direct drive
On a direct-drive turntable the motor turns the platter itself; on a belt drive an offset motor turns it through an elastic belt. The belt isolates motor vibration and, in doing so, removes the instant response DJs need.
Explore: Pitch and tempo calculator · Pitch fader · 45 adapter · All DJ terms