BMP to ICO converter
Convert BMP images to ICO in your browser.
Processed in your browser. This file is converted on your device and is never uploaded.
Converter
.bmp, .dib up to 50 MB. You can also drag a file here.
No file selected.
About this tool
BMP turns up in output from older Windows software, scanners, and some scientific instruments. An ICO holds several sizes in one file, so a browser or desktop can pick the right one instead of scaling a single image badly.
This tool converts BMP to ICO entirely in your browser. The image is decoded, drawn, and re-encoded on your device, so nothing is uploaded and the size of the file costs you no waiting.
Supported formats and limits
- Input
- .bmp, .dib
- Output
- .ico (image/x-icon)
- Output name
- The original name with the new extension, for example photo.bmp becomes photo.ico.
- File size limit
- 50 MB
- Processing
- In your browser. The file is not uploaded.
BMP against ICO
| Feature | BMP | ICO |
|---|---|---|
| Compression | None, stored as written | Lossless |
| Colour | 8 bits per channel | 8 bits per channel |
| Transparency | None | Full alpha channel |
| Animation | No | No |
| Keeps EXIF | No | No |
| Browser support | Every browser since 1995 | Every browser since 1999 |
| Size of a photograph | 8 to 20 times a JPG | Not a format for photographs |
| Published | 1990 | 1985 |
When you would want this
You need the background to stay transparent
ICO carries a full alpha channel and BMP does not carry a usable one, so this is the conversion that lets a logo or a cut-out sit on any background without a white box around it. Anything you are going to place over a coloured surface, a photograph, or a gradient wants to be in a format that can say a pixel is only partly there.
You are making a favicon
A browser looking for a tab icon asks for /favicon.ico, and expects a file holding several sizes rather than one. This writes 16, 32 and 48 pixel versions into a single ICO, each rendered from your BMP rather than scaled down from one another, which is what keeps the small one legible instead of smudged.
How to use it
- Choose a .bmp / .dib file, or drag one onto the page.
- Icon sizes 16, 32, and 48 pixels are written into the one file.
- Optionally set a width or height to resize at the same time.
- Select Convert, then download the ICO file.
Limitations
- Icons are square. A rectangular source is fitted into the square, which changes its proportions.
- An icon can be at most 256 pixels, which is a limit of the format.
- Metadata is not preserved. EXIF fields, including camera settings and GPS location, are dropped, which is a privacy benefit but worth knowing if you rely on them.
- Colour profiles are not preserved, so an image in a wide-gamut profile may shift slightly.
- The camera's EXIF orientation is applied, so a photo taken sideways comes out upright rather than rotated.
Common problems
The icon does not appear in the browser tab
Browsers cache favicons aggressively and often keep an old one, or none, for a while. A missing icon after converting BMP to ICO is usually the cache rather than the file.
Put the file at /favicon.ico in the site root, then load the page with a hard refresh, or open /favicon.ico directly to confirm the file itself is being served.
Other ways to do this
The program already on your computer
GIMP and dedicated icon editors; most image editors will not write one will open a BMP and save it as ICO, and if you have one of them installed and only one file to convert, that is a perfectly good answer. It stays on your machine the same way this does. Where it stops being convenient is a folder of forty files, or a machine you do not own.
ImageMagick, from a terminal
One command converts a directory: magick mogrify -format ICO *.BMP. If you already have it installed this is the fastest way to do a hundred files, and it scripts. It is also a dependency to install and a syntax to learn, which is a poor trade for converting one image once.
An online converter that uploads
Most sites offering this send your file to a server, convert it there, and give you a link back. They can do formats a browser cannot, which is a real advantage. The cost is that your file was on somebody else's machine, governed by a retention policy you did not read. That is the whole difference here: this page converts BMP to ICO using code your browser already downloaded, so there is no server holding it afterwards.
Frequently asked questions
- Is my image uploaded?
- No. The conversion runs entirely in your browser. The image never leaves your device and no request carrying it is made.
- Does converting to ICO lose any quality?
- The conversion itself does not. ICO is lossless, so every pixel it is handed is written exactly as it arrived and nothing is discarded on the way. What it cannot do is recover detail your BMP had already lost before it got here: a lossless format preserves what it is given, it does not restore what is gone.
- Why is my BMP file so enormous?
- Because BMP barely compresses: it stores each pixel more or less as written, so the size is width times height times bytes per pixel and almost nothing else. That is why it opens instantly and why it is impractical to send. Converting to ICO is the usual fix, and the size drops by a large multiple.
- Will this work as a favicon?
- Yes. The file holds 16, 32, and 48 pixel versions in one icon, which is what browsers expect at /favicon.ico, and each size is rendered from your image rather than scaled from one another.
- Can I resize while converting?
- Yes. Set a width, a height, or both. With proportions kept, one dimension is derived from the other, and giving both fits the image inside that box rather than distorting it.
- Do I need to install anything or create an account to use BMP to ICO converter?
- No, to all of it. BMP to ICO converter runs inside the browser you already have, with no sign-up, no download, no watermark on the result, and no cap on how many files you convert. There is nothing to uninstall afterwards either, because nothing was installed.
- Does BMP to ICO converter work offline?
- Once the page has loaded, yes. The conversion runs on your device, so it needs no connection to do the work. The first visit fetches the page and the code that does the converting; after that a lost connection stops nothing, and a converted file appears exactly as it would online.
- How large a file can BMP to ICO converter handle?
- The limit is 50 MB. It is a deliberate one rather than a technical ceiling: the real constraint is memory, and a file that decodes to more than the device can hold fails in a way that is hard to explain. Phones run out well before laptops do, which is why the limit is set where it is.
- Can I convert several files at once with BMP to ICO converter?
- Not here: this tool takes one file at a time, because what it does depends on choices you make about that particular file. Convert them one after another, or look at the batch converters in the same category, which are built for a folder at a time.