Car stereos have been internationally standardised since 1984. This makes it simple to determine whether a new stereo will fit your vehicle. The typical design is either Double-DIN or Single-DIN. DIN stands for Deutsches Institut fur Normung, the organisation that developed the standardisation. The width of every car stereo is 7 inches, which means the only thing you need to be concerned with measuring is the height and depth. By using a household tape measure, you can determine whether a new stereo will fit in your vehicle.
Measure your current car stereo, or the radio's cavity (if it does not currently have a radio). The width is standardised at 7 inches. However, the height could be Single-DIN (2 inches), Double-DIN (4 inches) or, in rare cases, DIN-and-a-half (3 inches).
Measure the replacement stereo using the above information. The replacement radio will be one of the listed DIN sizes (it is an international standard). If you are shopping for the stereo online or in a catalogue, simply look at the specifications. The radio size will be shown as "Double-DIN" or "Single-DIN."
Measure the depth of your stereo cavity and then measure the depth (or view the listed depth) of the new stereo. Stereo depths are not standardised, so there may be some inconsistency to the dimensions. Make sure the replacement stereo will have at least an inch or two of clearance so there is room for wiring and cable connections.
If the radio is not a direct fit (ex. Double-DIN to Double-DIN), you can purchase a mounting kit. These kits are ideal for swapping a Single-DIN radio into a Double-DIN slot (they create a casing around the radio, filling up the extra space). It can be difficult to change from Single-DIN to Double-DIN, but it is possible, depending on your vehicle's dash layout.