How much smaller will the JPG be?

In our tests photos got 11 to 35 times smaller: a 768 KB bitmap became 67 KB and a 34.3 MB one 1.0 MB. Screenshots shrink less, and black-and-white scans can grow.

Does converting lower the quality?

Slightly, because JPG is lossy. The file is saved at quality 90, where changes in photos are small; text and thin lines show faint smudges if you zoom in.

Yes. The JPG records the same DPI as the BMP, so it prints at the same size.

Why did my black-and-white BMP get bigger?

A 1-bit BMP uses one bit per pixel. JPG has no black-and-white mode, so the scan is stored as 8-bit grayscale, and JPG compresses sharp black-and-white edges poorly. Convert black-and-white scans to PNG instead.

Can I convert several BMP files at once?

Yes, up to 10 at a time. Download them one by one or all together as a ZIP.

What happens to my files?

The BMP is uploaded over HTTPS, converted on our server and deleted automatically within 2 hours, along with the JPG.

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Runs on our server
Photos 11 to 35 times smaller in our tests
Saved at JPG quality 90
DPI kept from the BMP

Convert BMP to JPG Online

Shrink large BMP bitmaps into JPGs that email, websites and phones accept.

Click to choose or drag & drop here

Up to 10 files · 50 MB each

How to Convert BMP to JPEG

1
Upload the BMP
From Paint, a scanner or older Windows software: 1-bit to 32-bit and RLE-compressed BMPs all work, up to 50 MB (up to 10 files at once).
2
Compressed as a JPG
The picture is saved at quality 90, with the same width, height and DPI as the bitmap.
3
Download and share
One file downloads as a JPG; several come as a single ZIP.

Why BMP files are so large

A BMP stores every pixel as it is, with no compression: three bytes per pixel for a full-color bitmap. A 4000 × 3000 photo therefore takes 34 MB, more than Gmail lets you attach (25 MB) and more than most upload forms accept. JPG compresses the same photo by discarding detail the eye barely notices; in our test it came to 1.0 MB.

File sizes we measured

Bitmap	BMP	JPG
512 × 512 photo, 24-bit	768 KB	67 KB
4000 × 3000 photo, 24-bit	34.3 MB	1.0 MB
1280 × 800 screenshot	2.9 MB	130 KB
512 × 512 black-and-white scan, 1-bit	32 KB	191 KB

What changes in the JPG

Width, height and DPI stay the same, so a 300 dpi scan still prints at its original size.
Palette (8-bit) and 16-bit bitmaps become full-color JPGs; grayscale bitmaps stay grayscale.
A 32-bit BMP with a transparent background is placed on white, since JPG has no transparency.
JPG is lossy. In our screenshot test the average pixel moved by less than 1 of 255 levels, but pixels beside text moved by up to 86, which shows as faint smudges around letters.

When to choose PNG instead

JPG is made for photos. Screenshots, diagrams and black-and-white scans have sharp edges and flat areas that PNG stores better and without any loss: our 1280 × 800 screenshot was 130 KB as a JPG but 60 KB as a PNG. A 1-bit scan even grows as a JPG (32 KB to 191 KB), because JPG has no black-and-white mode and stores it as grayscale. For those files, use BMP to PNG.

Figures on this page were measured by the PortImg team in October 2026, on a test copy of our server. How we test

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Frequently Asked Questions

: In our tests photos got 11 to 35 times smaller: a 768 KB bitmap became 67 KB and a 34.3 MB one 1.0 MB. Screenshots shrink less, and black-and-white scans can grow.
: Slightly, because JPG is lossy. The file is saved at quality 90, where changes in photos are small; text and thin lines show faint smudges if you zoom in.
: Yes. The JPG records the same DPI as the BMP, so it prints at the same size.
: A 1-bit BMP uses one bit per pixel. JPG has no black-and-white mode, so the scan is stored as 8-bit grayscale, and JPG compresses sharp black-and-white edges poorly. Convert black-and-white scans to PNG instead.
: Yes, up to 10 at a time. Download them one by one or all together as a ZIP.
: The BMP is uploaded over HTTPS, converted on our server and deleted automatically within 2 hours, along with the JPG.

Convert BMP to JPG Online

How to Convert BMP to JPEG

Upload the BMP

Compressed as a JPG

Download and share