Is BMP to PNG really lossless?

Yes. PNG compression is reversible, so the PNG decodes to exactly the pixels the BMP held. Nothing is approximated, blurred or thrown away, which is why this tool has no quality slider.

How much smaller is a PNG than a BMP?

Usually 2–5 times smaller. Images with large areas of flat colour, such as screenshots and diagrams, shrink the most; noisy photographs shrink the least. For photos, BMP to JPG gives a far smaller file.

Does it work with 8-bit and 32-bit bitmaps?

Yes. Indexed-colour 8-bit, 24-bit and 32-bit bitmaps are all decoded by the browser and saved as standard PNG files, and .dib files are accepted alongside .bmp.

Can I convert several files at once?

Drop up to 5 files per batch for free, or an unlimited number with Tinyvert Pro, and save them together with "Download all as ZIP". The ZIP is built on your device too.

Will the PNG open in older software?

PNG has been supported by every browser since the late 1990s and by Office, Paint, Photoshop, GIMP and every operating system since. Outside Windows it is far better supported than BMP.

BMP to PNG Converter — Lossless and Free

Convert BMP to PNG

Turn bulky Windows bitmaps into lossless PNG files that are identical pixel for pixel and a fraction of the size. No settings, no upload, no quality lost.

No upload — runs in your browser

Batch convert & ZIP download

Free, no sign-up

Drop BMP, DIB files here

Choose files

Free: up to 5 files per batch · Files never leave your device · Paste from the clipboard works too

Private by design

Your files are processed by your own device using WebAssembly and your browser's built-in codecs. Nothing is uploaded, logged or stored.

Fast & offline-ready

No queue, no waiting for a server. Once the page has loaded it even works without a connection.

Works everywhere

Chrome, Edge, Firefox and Safari on Windows, macOS, Linux, Android and iOS. No app to install.

Same pixels, a fraction of the space

BMP and PNG are both lossless, so converting between them changes nothing about the picture. What changes is how the pixels are stored. A bitmap writes every pixel in full, which means a plain white 1000×1000 image costs 3 MB. PNG filters each row and runs the result through DEFLATE, the same algorithm ZIP uses, so repeated colours and smooth gradients collapse to very little. The output is typically 2–5 times smaller than the bitmap, and images dominated by flat colour shrink the most.

Who still makes BMP files

Source	Why it is a bitmap
Microsoft Paint	24-bit bitmap was the default save type for years
Scanner utilities	Many bundled drivers offer BMP as their "no compression" option
Older screenshot tools	Writing a bitmap needs no encoder, so early capture apps used it
Embedded devices	Firmware, instrument panels and machine-vision cameras export raw bitmaps
Windows internals	Wallpapers, icon resources and clipboard images are stored as DIB

None of these are mistakes, but a bitmap is a poor file to keep or share. Many web services refuse to open it, it eats email attachment limits, and it offers nothing PNG does not.

What the conversion keeps

Every pixel, exactly. The PNG decodes to the same colour values as the bitmap.
The original dimensions. Nothing is scaled, cropped or padded.
Full colour depth. The PNG is written as a standard 32-bit RGBA file that any program can open.

Bitmaps carry no EXIF data, colour profile or comment fields worth speaking of, so there is no metadata to lose. The browser decodes the file, draws it to a canvas and encodes the PNG. Your files stay in memory on your own device and are discarded when you close the tab.

Where to go next

PNG is the right format to keep, but not always the right one to publish. For a website, PNG to WebP cuts the size again while keeping any transparency. If the bitmap is a logo destined for a browser tab, PNG to ICO builds a multi-size favicon from it. Photographs and scans that will only ever be viewed, not edited, are better off as JPG: BMP to JPG makes them 10–20 times smaller instead of 2–5. The guide to WebP, PNG and JPG explains how to choose.

Batches and large files

Up to 5 bitmaps convert in one go, one after another with a progress bar each, and "Download all as ZIP" packs the results locally. Because the bitmap and the PNG both live in your browser's memory during conversion, very large scans are limited by your device's memory; a desktop will handle files a phone may not. Everything also works offline after the first visit.

How to convert bmp to png — step by step

Drag BMP files into the drop zone, or click "Choose files" and select them.
There is nothing to configure. Each bitmap is decoded and written out as a PNG straight away, with a progress bar per file.
Compare the new size shown in each row, then download the PNGs individually or all together as a ZIP.

Frequently asked questions

Is BMP to PNG really lossless?: Yes. PNG compression is reversible, so the PNG decodes to exactly the pixels the BMP held. Nothing is approximated, blurred or thrown away, which is why this tool has no quality slider.
How much smaller is a PNG than a BMP?: Usually 2–5 times smaller. Images with large areas of flat colour, such as screenshots and diagrams, shrink the most; noisy photographs shrink the least. For photos, BMP to JPG gives a far smaller file.
Does it work with 8-bit and 32-bit bitmaps?: Yes. Indexed-colour 8-bit, 24-bit and 32-bit bitmaps are all decoded by the browser and saved as standard PNG files, and .dib files are accepted alongside .bmp.
Can I convert several files at once?: Drop up to 5 files per batch for free, or an unlimited number with Tinyvert Pro, and save them together with "Download all as ZIP". The ZIP is built on your device too.
Will the PNG open in older software?: PNG has been supported by every browser since the late 1990s and by Office, Paint, Photoshop, GIMP and every operating system since. Outside Windows it is far better supported than BMP.