Is this BMP to ICO converter really free?

Yes. Up to 5 files at a time, no signup, no catch. The free tier adds a small watermark to image output — Pro ($9.99/mo or $49/yr) removes it, raises the file size limit to 500 MB, and unlocks unlimited batch conversion.

Are my files uploaded to a server?

No — and you can verify it yourself. Open DevTools → Network tab, then convert a file. You'll see zero upload requests. Everything runs right in your browser. We never see your files.

How long does conversion take?

Usually 1–3 seconds for a typical file. The very first conversion on a fresh page load may take 5–20 seconds while the converter engine loads — after that it's instant. Your CPU does all the work locally.

What is the file size limit?

Free: up to 10 MB per file, 5 files per batch. Pro: up to 500 MB per file, unlimited batch. If you're working with large videos or RAW photos, Pro is built for that.

Can I batch convert multiple BMP files at once?

Yes — drop multiple files at once (or Ctrl/Cmd+click to select them) and they all convert in parallel. Free accounts handle up to 5 files per batch; Pro has no limit.

Will the image quality change after conversion?

It depends on the formats involved. Converting to a lossless format like PNG preserves every pixel exactly. Converting to a lossy format like JPEG or WebP applies compression — we default to 85% quality, which looks identical to the original for almost all images. You won't notice a difference unless you zoom in pixel-by-pixel.

Do you support batch image conversion?

Yes — drop multiple images at once and they all convert in parallel. Free accounts handle up to 5 at a time; Pro is unlimited. Download everything as a single ZIP when you're done.

What BMP size should I start with?

Use at least a 256×256 pixel BMP and crop it to a square before converting. The converter scales down to the standard ICO sizes (16, 32, 48 px) and a larger source produces better-quality small frames.

Can I use a BMP with a background colour as a transparent ICO?

Not automatically. BMP without an alpha channel will produce an ICO with that background colour. For a transparent favicon, start from a PNG with transparency instead.

How private is this converter?

Completely private — by design, not policy. There is no upload endpoint. Files are processed right inside your browser tab and disappear the moment you close it. We collect only anonymous page-view counts; your file content is never seen or stored.

BMP to ICO Converter — Free, Online, No Upload

How to convert BMP to ICO online

1
Drop your BMP file
Drag and drop your Bitmap Image File file onto the converter, or click to browse your files. You can select up to 5 at once. Nothing leaves your device — conversion happens right here in the browser.
2
Hit Convert — it happens locally
Click Convert and watch it go. There's no upload, no server queue, no waiting. The converter runs Bitmap Image File → Windows Icon Format entirely in your browser tab. Most files finish in 1–3 seconds.
3
Download your ICO
Your Windows Icon Format file is ready. Click Download, or grab a ZIP if you converted a batch. Close the tab and everything disappears — no copies kept anywhere.

BMP vs ICO: format overview

BMP

Bitmap Image File

Microsoft · 1987

Compression: none
Transparency: No

✓ No compression — original pixel data preserved
✓ Universal Windows support
✗ No compression = massive files

ICO

Windows Icon Format

Microsoft · 1985

Compression: lossless
Transparency: Yes

✓ Multiple resolutions in a single file
✓ Required format for Windows app icons and favicons

BMP magic bytes: 42 4D

ICO magic bytes: 00 00 01 00

Why convert BMP to ICO?

BMP files are sometimes used for image assets in older Windows application development — resource editors, legacy toolkits, and older versions of Visual Studio worked heavily with BMP for icon source images. To use those BMP images as application icons or favicons, they need to be converted to ICO format, which is what Windows and browsers actually use.

ICO is a container that holds one or more image sizes. Windows uses different sizes depending on context: 16×16 for the taskbar, 32×32 for desktop icons, 48×48 for file explorer large icons, and 256×256 for high-DPI displays. Converting a BMP to ICO handles both the format conversion and the generation of multiple size variants from the source image.

For best results, the BMP should be a square image with the intended icon graphic centered and scaled appropriately. Complex photographic BMPs don't translate well to icon sizes — detail disappears at 16×16 pixels. Simple graphics, logos, symbols, and high-contrast images work well. BMP's lack of transparency support means that any areas you want transparent in the icon will need to be a specific background color that the converter can treat as transparent, or the icon will have a solid background at all sizes.

Quality & file size: BMP to ICO

Typical file sizes: BMP 35–40 MB → ICO 10–100 KB.

Both BMP and ICO use lossy compression. We transcode at high quality settings (equivalent to ICO's recommended web quality) to minimize generational loss.

Color depth: BMP supports standard color, ICO supports standard color.

Transparency: BMP does not support transparency. ICO preserves transparency.

Frequently asked questions

Privacy: how FormatDrop handles your files

Your BMPfiles are converted 100% inside your browser. They are never uploaded to our servers, never stored, and never seen by anyone other than you. This isn't a privacy policy claim — it's an architectural guarantee: our server has no endpoint that receives file bytes.