What RPM means
RPM stands for revolutions per minute: how many full turns a record makes on the platter in one minute. A record has to be played at the speed it was cut for, or the pitch and tempo will be wrong.
The three standard speeds
- 33 1/3 RPM: the usual speed for 12-inch LPs. A side typically holds somewhere around 20 minutes of music.
- 45 RPM: the usual speed for 7-inch singles, and also used for some 12-inch releases. A 7-inch side holds a few minutes.
- 78 RPM: the older speed used for most records made before the mid-1950s. A side typically holds around three to five minutes.
Record sizes and playing times overlap, so size is a clue rather than a rule.
How the speeds came about
Early disc records were played at a range of speeds before around 78 RPM became the common standard for shellac discs. Slower microgroove records arrived later, with the 33 1/3 LP and the 45 RPM single introduced around the late 1940s by competing companies. Slower speeds with finer grooves allowed longer playing time, while 45s offered convenient singles. Details differ by source, so treat exact dates with caution.
How to tell which speed a record needs
- Read the label. Most labels print the speed, such as 33, 45 or 78.
- Check the size. 12-inch discs are most often 33 1/3, 7-inch discs most often 45, and older 10-inch discs are often 78.
- Look at the material and grooves. Heavy, brittle discs with wide grooves are usually 78s. See how to play 78 RPM records for the equipment these require.
- Listen. If the music sounds slow and deep, the speed is too low; fast and high, too high.
Are all 10-inch records 78 RPM?
No. Many 10-inch records are 78s, but 10-inch records have also been issued at other speeds, so check the label.
Which speeds are most common today?
Most new albums are 33 1/3 RPM, and many singles and some special-edition albums are 45 RPM. 78s are now mostly collector items.
Does speed affect sound?
Faster speeds can allow wider groove spacing, which some listeners prefer, at the cost of less playing time per side. Many other factors matter too, including pressing quality and equipment.
What happens at the wrong speed
The music plays at the wrong pitch and tempo. Playing at the wrong speed is not usually harmful by itself, but playing a 78 with a standard stylus can wear the record. Make sure you have the right stylus and, if the disc is dirty, consider cleaning it first.
FAQ
Why was 78 RPM chosen? It became a common standard for shellac discs in the early recording era, balancing sound quality and playing time.
Are most records 33 or 45? Most albums are 33 1/3; most singles are 45.
Can I play a 78 on a regular record player? Only if it has a 78 setting and a suitable stylus.