AVIF to BMP Converter
Some older programs, embedded tools and classroom software only understand the plain bitmap format. If your picture is an AVIF, they will not open it at all. This page converts AVIF to a standard 24-bit BMP file entirely in your browser tab, so you can hand legacy software a file it recognises without uploading anything.
How to convert AVIF to BMP
- Add your AVIF files by dropping them, clicking the drop zone or pasting.
- The output format is already set to BMP. Adjust quality or size if you need to.
- Press Convert and compare the original and new size for each file.
- Download each file or all of them as a ZIP.
When to convert, and when not to
- Legacy software, a device or a script asks specifically for a BMP file.
- You need raw pixel data that is simple to read in your own code.
- A tutorial or assignment requires the bitmap format.
- Do not convert for sharing or publishing. BMP files are uncompressed and large, so e-mail and web pages are better served by JPG, PNG or WebP.
What changes
- The output is a 24-bit BMP with no compression, so the file is big compared with the AVIF.
- BMP made here has no transparency. Transparent areas are filled with the background colour you pick.
- Pixels are stored exactly as the AVIF decodes; no further detail is lost.
- Your browser must be able to open AVIF to read the source file.
- Metadata and animation are not kept.
What a BMP file actually is
BMP is one of the oldest image formats on desktop computers. The version made here stores three values for every pixel, red, green and blue, one row after another. Nothing is compressed, which is why almost any program can read it and why the file takes up so much space.
AVIF sits at the opposite end, with heavy compression to keep downloads small. Going from AVIF to BMP therefore expands the same picture into its plain pixel form.
Bitmap files are also easy to inspect. Each pixel sits at a predictable position, so a short script can read or change values without a decoding library, which is one reason teaching material and small utilities still ask for them.
Handling transparency on the way
The 24-bit BMP written by this tool has no alpha channel. If your AVIF contains see-through parts, they are painted with the background colour before the file is saved. Choose a colour that matches the place the bitmap will be used, for example white for printing or black for a dark interface.
When transparency matters, choose PNG instead; it keeps the see-through areas.
A white fill is the usual choice for printing and a black fill suits dark interfaces. Preview the downloaded file in a program that shows the picture on a checkerboard or a coloured page to confirm the edges look right.
If the AVIF is mostly flat colour, the opaque result looks the same as the original on a white page. If the artwork has soft shadows, they are blended with the fill colour, so choose the colour of the surface it will sit on.
Keeping BMP sizes under control
Because nothing is compressed, the file size depends on the pixel dimensions of the picture, not on what it shows. A large photograph will give a large bitmap whatever its content.
If your legacy tool only needs a thumbnail, use the resize options to reduce the width and height before converting. Compare the size shown in the list with the original AVIF to see the difference for your file, then decide whether the resulting bitmap is practical.
A BMP made here follows the usual layout, with rows stored from the bottom up. Programs that read bitmaps handle that automatically, so you do not need to do anything, but it is useful to know if you read the file with your own code.
Privacy: your files stay on your device
- The tool decodes, resizes and encodes your pictures with your browser. The files are never sent to a server.
- To check it yourself: open the browser developer tools (F12), open the Network tab, convert a file, and look for any request that carries your image. You will see none.
Frequently asked questions
Why is the BMP so much bigger than the AVIF?
BMP is uncompressed. It stores every pixel, while AVIF compresses heavily.
Does BMP support transparency here?
No. The BMP made by this tool is 24-bit, so transparent areas take the background colour.
Which colour depth does the BMP have?
24-bit colour, which is the common choice for photographs and graphics.
The AVIF file will not open. Why?
Your browser must decode AVIF. Try a current Chrome, Edge or Firefox.
Can I shrink the BMP?
Yes, reduce the pixel size with the percent or max size option before converting.
Which programs open the BMP?
Most image viewers and editors do. If one does not, check that it supports 24-bit bitmap files.