The most common form of the vinyl single is the 45 or 7 inch, the names are derived from its play speed, 45 rpm and the standard diameter 7" (18 cm).
The 7" 45 rpm record was introduced in 1949 by RCA as a smaller, more durable and higher-fidelity replacement for the 78 rpm shellac discs. The first 45 rpm records were monaural, with recordings on both sides of the disc. As stereo recordings became popular in the 1960s, almost all 45 rpm records were produced in stereo by the early 1970s.
Although 7" remained the standard size for vinyl singles, 12" singles were introduced for use by DJs in discos in the 1970s.
| Diameter | Revolutions per minute | Time duration |
| 12 in. (30 cm) | 33 1/3 rpm |
45 min Long play (LP) |
| 45 rpm |
12-inch single, Maxi Single, and Extended play (EP) | |
| 10 in. (25 cm) | 33 1/3 rpm |
Long play (LP) |
| 78 rpm |
3 minutes | |
| 7 in. (17.5 cm) | 45 rpm |
Single, and Extended play (EP) |
| 33 1/3 rpm |
Often used for childrens records in the 1960s and 1970s. |
