Turn PNG files into BMP in your own browser

Content last reviewed:2026-09-30

Add your PNG files and download BMP files in the most widely read form of the format. In our measurement a landscape photo grew from 3.06 MB to 7.03 MB.

Files in queue

Add PNG files on the left to start converting to BMP.

What is PNG and what is BMP?

PNG is a lossless format: it keeps every pixel of the image, stores full transparency and opens in every browser[1]. W3C approved the third edition of the specification on 24 June 2025. It describes lossless storage by the deflate method, 8 or 16 bits per colour channel, an alpha channel and APNG animation[2].

BMP is the bitmap format of Windows. A file is made of a file header, an information header, a colour table and an array of pixels[3]. In the form our converter writes there is neither compression nor a transparency channel.

Turning PNG into BMP helps when an older program or a device takes that format and nothing else. The file comes out heavier, because every pixel takes three bytes with no packing: the landscape photo grew from 3.06 MB to 7.03 MB.

A graphics tablet with a stylus and a mouse on a desk mat — BMP is taken by programs and devices that cannot handle newer image formats. Photo: Workperch, Unsplash.

How do you convert PNG to BMP?

Drag your files onto the Add files area, or click it to pick them from your disk. Any number of PNG files is fine, each up to 100 MB.
Click Convert. Every finished file gets the Done status.
Save one file with Download, or all of them with Download all, which packs several into a ZIP archive. Only the extension changes, to .bmp.

The queue shows every file with its Before and After weight, the difference in percent, and the batch totals.

BMP has no quality setting, because the converter writes every pixel on 24 bits with no compression. The file header carries a resolution of 96 dots per inch, and every row of pixels is padded out to whole four bytes.

Remove takes one file out of the queue, Clear all empties it.

Everything happens in your own browser: the PNG file is read by an image element, and the BMP is assembled by our own code in the browser.

How much does a file weigh before and after PNG to BMP conversion?

Eight PNG files went through this converter with no quality setting, because nothing is compressed: two Unsplash photos at different resolutions, a product photo, a leaf macro, a real screenshot with text, a logo and an icon with a transparent background, and a page of text at scanner resolution. Weights are written the way the tool prints them in the queue: in kilobytes and megabytes of 1024 bytes, with the same rounding. We took the measurement ourselves on 11 September 2026 in a Chromium browser, and the result depends on the content of the image, so your file may come out differently.

Test file	Dimensions in pixels	PNG	BMP	Change
Landscape photo	1920 × 1280	3.06 MB	7.03 MB	2.3 times larger
High-resolution camera photo	4000 × 2667	11.1 MB	30.5 MB	2.7 times larger
Product photo on a light background	1200 × 1200	2.12 MB	4.12 MB	94 percent larger
Leaf macro with fine detail	1600 × 2015	6.52 MB	9.22 MB	42 percent larger
Screenshot with text	1440 × 900	100.5 KB	3.71 MB	37.8 times larger
Logo with a transparent background	1024 × 1024	52.1 KB	3.00 MB	58.9 times larger
Icon with transparency	256 × 256	6.57 KB	192.1 KB	29.2 times larger
Text page, as from a scanner	1654 × 2339	240.1 KB	11.1 MB	47.2 times larger

The weight of a BMP follows straight from the pixel dimensions: three bytes per pixel plus the header and the row padding. The weight of your own file sits in the Before and After fields of the queue.

Why is a BMP heavier than a PNG?

BMP writes every pixel on its own and packs nothing, so the weight depends on the pixel dimensions alone. The landscape photo at 1920 × 1280 pixels comes out 2.3 times larger, and the product photo on a light background comes out 94 percent larger. With a photograph full of detail the difference is smallest, because there is little for PNG to squeeze either.

Graphics with flat areas grow the hardest. The screenshot with text (1440 × 900) comes out 37.8 times larger, and the logo with a transparent background at 1024 × 1024 pixels comes out 58.9 times larger. A flat background costs a few bytes in PNG, and in BMP exactly as much as a photograph full of detail.

If the file does not have to be a BMP, a lighter result comes from the PNG to JPG converter, and with transparency kept from the PNG to WebP converter. The way back is the BMP to PNG converter, and you set smaller pixel dimensions in the image editor.

PNG versus BMP: how do the formats differ?

The table gathers the properties that decide when a BMP is needed and when it only takes up room.

Property	PNG	BMP
Storage from our converter	lossless, by the deflate method	lossless, with no compression at all
Transparency	yes, a full alpha channel	no
Bits per pixel	24 or 48, plus opacity	24
Resolution in the header	optional	96 dots per inch
Browser support	every version of every browser	yes, though pages do not use it
Typical use	graphics on a page	older programs and devices on Windows

The structure of a BMP file according to Microsoft documentation[3], PNG according to the W3C specification[2]. We read the bits per pixel, the absence of compression and the header resolution in the code of our own encoder.

Which PNG files does the converter take?

We checked every row on files put through the converter on 15 September 2026. The right column says what you get.

The file you add	What the converter writes in BMP
A photo or graphic saved as PNG	an uncompressed BMP, 24 bits per pixel, at the same dimensions
A PNG with a transparent background	a BMP with a white background, because this form of the format has no transparency channel
A PNG with a semi-transparent shadow or glow	a BMP in which semi-transparent pixels are blended with white
A PNG with 16 bits per colour channel	a BMP with 8 bits per colour channel, because that is what this form of the format holds
An animated PNG (APNG)	the first frame of the animation, and the queue carries a note: This file is animated, so only the first frame is saved.
A file with EXIF data, for example a rotated photo	a BMP with no EXIF data, but in the orientation stored in that data
A file larger than 100 MB	the message File is too large (max 100 MB).
A damaged file, or text with a .png extension	the Error status and the message Failed to load the image.

Files in other formats are skipped as they are added, with the message: Add PNG files. Files in other formats were skipped.

What happens to transparency, colours and EXIF data?

A transparent background from a PNG file comes out white in the BMP, and semi-transparent pixels are blended with white. That is how this form of the format works: 24 bits per pixel mean three colour components and nothing more.

The BMP file is put together here by our own encoder running in the browser. A browser canvas writes this format in Firefox only, while Chrome, Edge and Safari hand back a PNG with a BMP extension. We write one form of it, the one read most widely: 24 bits per pixel, no compression, with a BITMAPINFOHEADER.

EXIF data does not reach the BMP file, and the orientation stored in that data is applied. If the file is meant for print rather than for an older program, consider the PNG to TIFF converter or a document from the PNG to PDF converter.

Convert other files to BMP

AVIF to BMP JPG to BMP WebP to BMP TIFF to BMP

Convert PNG to other formats

PNG to JPG PNG to WebP PNG to AVIF PNG to GIF PNG to TIFF PNG to PDF PNG to Base64

Sources

Image file type and format guide — MDN Web Docs
Portable Network Graphics (PNG) Specification (Third Edition) — W3C
Bitmap Storage — Microsoft Learn

The file sizes in the tables were measured by running finished images through this converter in a browser, and we report them the way the tool counts them. What the page says about either format rests on the sources listed above.

Content last reviewed: September 30, 2026 · written and checked by the Arteon team

Common questions about turning PNG into BMP

How do you turn PNG into BMP for free?

Drag your PNG files onto the Add files area, click Convert and save the result with Download all. The converter is free, needs no account, and your files stay on your own device.

Why does the BMP weigh so much more?

Because there is no compression in it: every pixel is three bytes. In our measurement the landscape photo comes out 2.3 times larger and the logo with a transparent background comes out 58.9 times larger, because a flat background costs as much here as fine detail.

What happens to a transparent background?

It comes out white, and semi-transparent pixels are blended with white. This form of BMP has no transparency channel. If the background has to stay transparent, keep the PNG or choose WebP.

Does the image quality drop?

Not with an ordinary PNG file: the storage is lossless, so every pixel stays as it was. The only change is with files that hold 16 bits per colour channel, because those come out with 8 bits.

Which form of BMP does the converter write?

The one read most widely: 24 bits per pixel, no compression, with a BITMAPINFOHEADER and a resolution of 96 dots per inch. Every program that opens the format at all takes it.

Can I convert many files at once?

Yes. The queue takes any number of files, each up to 100 MB, and you can add them in batches because it keeps the earlier ones. The Download all button packs the finished files into a single ZIP archive.

Why does your own encoder write the BMP instead of the browser?

Because a browser canvas writes this format in Firefox only. Chrome, Edge and Safari hand back a PNG with a BMP extension, so we assemble the file ourselves, byte by byte.

Are the files uploaded to a server?

No. The PNG file is read by the browser on your own device, and the BMP is built in that same browser. Nothing of them is left once you close the page.