The Difference Between Dual-Layer and Double-Sided DVDs

Recordable DVDs are available in several different formats to accommodate various uses and capacities. Two of the most common are dual-layer and double-sided. Dual-layer (DL) and double-sided (DS) DVDs further break down into a few different kinds. While this can be confusing, a couple acronyms are commonly used:

• R: Recordable, but only once; cannot be overwritten.
• RW: Rewriteable; can be erased and overwritten.

Each has a total of two recordable layers, holds an enormous amount of data, and looks identical to the other, but dual-layer and double-sided mean two very different things. 

Dual-layer recordable DVDs, which are denoted with "DL," come in two formats:

• DVD-R DL 
• DVD+R DL

Each of these DVDs has only one side, but that single side has two layers to which data can be written. Together, the two layers hold a total of up to 8.5GB—capacity for about four hours of video—making this DVD format ideal for most home or business uses.

The "R" refers to technical differences in the way data is recorded and read, but you won't notice much difference between the two. Check your DVD burner's documentation to make sure it includes support for DVD-R DL, DVD+R DL, or both.

In simple terms, double-sided (DS) recordable DVDs can hold data on two sides, each of which has a single layer. A double-sided DVD holds about 9.4GB of data, which is about 4.75 hours of video.

DVD burners that support DVD+/-R/RW discs can burn to double-sided discs; all you have to do is burn to one side, flip the disc like an old LP record, and burn to the other side.

To further confuse the matter, rewriteable DVDs are available with two sides and two layers. As you might expect, these hold considerably more data, generally about a whopping 17GB.

Movies are typically available on single-sided, dual-layer DVDs. Some movies are sold as sets, with the movie and extra footage on one DVD, and other versions (such as full-screen) on another. Movies sold on double-sided DVDs often separate these items similarly, but on opposite sides rather than separate disks. Very long movies are sometimes split between the two sides; the viewer must flip the DVD in the middle of the film to continue watching.

Older computers are typically equipped with optical disk drives (which read and burn DVDs). Given the advent of cloud storage and digitized media, however, many new computers lack this feature. If you'd like to play or create DVDs and your computer is so equipped, check its documentation to see what types of DVDs are compatible. If no optical drive is included, you can buy a standalone one; again, check the documentation to see which DVD format is appropriate for the model you choose.