What Is The Width Of A File?

Width is the horizontal size of whatever picture a file contains, counted in pixels. It is the first of the two numbers in a size written as 1920 x 1080, and it should not be confused with the size of the file on disk.

Which files have it, and where the number comes from

Almost any file with something to display carries a width. Images do, of course: JPEG, PNG, GIF, WebP, HEIC, TIFF and camera RAW. So do videos such as MP4, MOV, MKV and AVI, and documents such as PDF, where each page has a size. Even audio files can show one. There is normally no picture in an MP3 or a FLAC, but if the file has cover art embedded in it, that artwork has a width, and it appears in the report.

Nobody types this value. A camera or phone sensor sets it for a photo, the encoder or the camera sets it for a video, a scanner sets it for a scan, and an image editor sets it when you resize or export. Changing the width means changing the picture itself, which is why it cannot simply be edited like a title or an author name.

A general Width row is not quite the same as an Image Width row. Image Width refers specifically to the pixel width of an image, while the general Width is reported for any kind of file, including the ones above that are not images at all.

What a typical value looks like

You get a whole number of pixels, usually with no unit shown: 1920 for a Full HD video, 3840 for a 4K one, and something like 4032 for a photo from a twelve megapixel phone camera.

Two things about that number regularly surprise people. A portrait video shot on a phone often stores 1920 as its width along with a rotation flag, so the player turns the picture upright and the stored number looks wrong. And some video files store a coded width plus a separate aspect ratio hint, which means the picture you watch can be wider than the number here.

It is also worth repeating that width is not file size. A wider file is usually a bigger file, but the two are measured differently and can move apart: a wide photo saved with heavy compression can easily be smaller on disk than a small one saved with none.

Why it matters

Width sets how much detail there is to work with, so it decides how large a picture can be shown or printed before it starts to look soft. That matters most because the loss is one way. Once an image has been scaled down, enlarging it again cannot bring back what was thrown away. If you print, the width is half of the calculation: the pixel width divided by the printing resolution gives you the printed size.

It is also the number that decides whether a file will be accepted. Upload forms, advertising specifications, printing services and some televisions and players set maximum or exact dimensions, and this row is how you check before you send. Fewer pixels across also means less data to store and stream, which is why resizing is the first thing to try on a file that is too big.

Width holds no personal information. It can still be a clue: an unusual value hints at the device or the software that produced the file, and a width well below a camera's native size shows that what you are holding has already been resized from an original.