How to Convert BMP to TIFF in Your Browser

How BMP becomes TIFF

1. The browser reads the BMP's pixel array directly — BMP is typically already stored uncompressed (occasionally with simple RLE compression, which the decoder also resolves), so there's little decoding work beyond parsing the header and pixel layout.
2. Each pixel is converted to RGBA. Most BMP files are 24-bit with no alpha channel at all, so the alpha value for those pixels is set to fully opaque; if the source is a 32-bit BMP with a genuine alpha channel, that data carries through instead.
3. That RGBA pixel grid is written into a TIFF container with its own header and tags — but, like the BMP source, without any compression scheme applied to the pixel data itself.
4. The output downloads as a single .tiff file at the same pixel dimensions as the source BMP.

What changes when you convert

File size is the notable exception to how conversions on this site usually work: converting an uncompressed source to TIFF normally means a size increase, but BMP is already uncompressed pixel data, and this TIFF encoder also writes uncompressed pixel data. The two files end up close in size — TIFF's more elaborate tag-based header can make it marginally larger — but there's no meaningful compression gain or loss in either direction. If you're converting BMP to TIFF expecting a smaller file, that's not what this conversion does.

Transparency depends entirely on the source, which is unusual to call out for BMP: the vast majority of BMP files are 24-bit RGB with no alpha channel at all, so most conversions produce a fully opaque TIFF. On the rarer 32-bit BMP that does carry a real alpha channel, that transparency is preserved rather than discarded.

Color data itself is essentially just repackaged, not reprocessed — since neither format applies lossy compression, no pixel values are altered by the conversion; only the container format changes.

When TIFF is the right choice — and when it isn't

Choosing TIFF over BMP makes sense when a workflow specifically expects TIFF's container and tag structure — scanning software, prepress and print pipelines, and archival systems often default to TIFF as their standard interchange format even for images that started out as simple BMP files, and TIFF's tag-based metadata support is broader than BMP's minimal header.

If your actual goal is a smaller file, neither BMP nor this TIFF output will get you there — both are uncompressed. For that, AVIF or WebP will compress the same pixel data down to a fraction of the size; if you just need the file to stay in a raw, legacy-Windows-friendly form, BMP itself may already be all you need without converting at all; for an application icon, use ICO.

Limitations and privacy

Because both formats are uncompressed, this conversion doesn't reduce file size the way converting from a compressed source typically does — plan for the TIFF to be roughly the same size as the BMP, not smaller. Alpha transparency only appears in the output if the source BMP genuinely had it, which most don't.

Conversion happens locally in your browser — the BMP is parsed and the TIFF is written on your device, with no upload to a server.