How to open .BMP files (Windows bitmap images) on Android, Windows and Linux

BMP files tend to come from older places: a scanner, a long-serving Windows program, a machine at work, a USB stick from a relative’s PC, or a game’s folder. Computers usually open them, but they’re surprisingly big, and on a phone it’s not always clear what can show them.

Folders opens BMP files, and the much older WBMP, in its image viewer on Android, Windows and Linux, for free. It can also turn a bulky BMP into a far smaller PNG without changing a single pixel.

What is a .BMP file?

BMP is the bitmap format that has been part of Windows, and of IBM’s OS/2, since their early days. Programmers also call it a DIB, a device-independent bitmap. It’s about as simple as an image format gets: a short header that starts with the letters BM, sometimes a colour table, then the pixel values row by row, usually starting with the bottom row.

Most BMPs aren’t compressed at all. That makes them easy for any program or small device to read, and very large. A 4000 × 3000 photo at 24 bits per pixel takes about 36 MB as a BMP, where a good JPEG of it would be a few megabytes.

BMP can store 1, 4, 8, 16, 24 or 32 bits per pixel, with optional run-length compression for 4- and 8-bit images. Later versions of the header added transparency for 32-bit files, but many programs ignore it.

Extension	What it is
.bmp	Windows bitmap: simple, usually uncompressed, from black and white to full colour
.wbmp	Wireless Bitmap: a tiny one-bit, black-and-white format made for the WAP pages of early mobile phones, around the turn of the century

How to open a .BMP file with Folders

Android

1. Install Folders from the download page and allow access to your files.
2. Find the file. If it came from a PC, it’s wherever you copied it, often Download; type *.bmp in the search box to list all of them under the folder you’re in.
3. Tap it. From an email or chat app, use Open with → Folders.

Windows and Linux

1. Install Folders, browse to the BMP and double-click it.
2. On Windows, File Explorer’s right-click Open with menu lists Folders for BMP and WBMP files once it’s installed.

What you can do with a BMP in Folders

• View it: zoom in, move through the folder with swipes or the arrow keys, see Details, Share it or Open with another app.
• Shrink it without loss. Select the BMP, or a whole folder of them, and choose Convert to ▸ PNG. PNG is lossless too, so the copy is identical pixel for pixel, usually at a fraction of the size.
• Shrink it further. Convert to ▸ JPEG makes the smallest copy of a photo, with a small loss of quality. WebP, AVIF (on Windows and Linux), HEIC, TIFF, GIF, ICO and TGA are on the same menu.
• Make a BMP. Some old programs, embedded devices and game mods insist on BMP. Select a PNG or JPG and choose Convert to ▸ BMP.
• Resize… makes smaller copies.
• Copy all text copies the words from a scanned page or screenshot saved as BMP.

WBMP files open in the same viewer, but Convert to doesn’t take them. To turn a WBMP into a PNG, use ImageMagick (magick input.wbmp output.png) or XnView MP.

Other ways to open .BMP files

• Windows: Paint and Photos open BMP. Linux: any desktop image viewer.
• Android: most gallery apps can show BMP.
• Web browsers display a BMP dragged into a tab.
• XnView MP (Windows and Linux) for unusual variants, WBMP included.

Problems opening a .BMP file?

The file is enormous. That’s normal for BMP. Convert a copy to PNG and keep that instead.

The picture is slanted, striped or upside down. BMP rows are padded to a multiple of four bytes and usually stored bottom-up. A program that writes the header wrongly, or a reader that gets the padding wrong, produces a skewed or flipped image. Try another viewer; if the file itself is faulty, ask for it again.

Transparent areas show as black. Transparency in 32-bit BMPs was added late, and many programs ignore it or write it differently. If you need transparency, ask for a PNG.

It won’t open at all. Rare variants, such as old OS/2 headers or unusual compression, aren’t read by every program. XnView MP reads most of them, and saving a PNG copy there gives you a file anything opens.

Questions people ask

Can I open a .BMP file on Android? Yes. Folders shows BMP files from any folder on your phone, free and offline.

Is BMP better quality than JPG? It’s lossless, so nothing is thrown away, unlike JPG. But PNG is lossless too and much smaller, so there’s rarely a reason to keep a BMP.

How do I convert BMP to JPG? Select the files in Folders and choose Convert to ▸ JPEG. The JPGs are saved next to the BMPs, which stay as they were.

What is a .wbmp file? A one-bit black-and-white picture from the early mobile web, usually tiny. Folders shows it; use ImageMagick or XnView MP to convert it.

Icons store their pictures much like BMPs: see the ICO guide. For a modern lossless format, read the PNG guide, or browse all 382 file types Folders opens.