Format
JPG, the picture format everything opens.
A JPG trades a little detail for a much smaller file, and every device, website and printer on earth understands it.
Flex Convert writes JPG with its own encoder, so the result is the same in every browser.
Facts
The record.
Extensions
.jpg and .jpeg, the same format.
Compression
Lossy, based on the discrete cosine transform. Detail the eye misses is discarded first.
Colour
8 bits per channel, no transparency and no animation.
Metadata
EXIF can hold camera, date and GPS position, and most phones write all three.
Largest picture
65,535 pixels on a side, a limit of the format itself.
In Flex Convert
Read and written. Our encoder is about 20 percent smaller than Chrome's own at the same measured quality, and writes no metadata.
Measured examples
What we measured.
JPG as the result of a conversion and of a resize, on generated pictures.
| Test file | Size | Change | Time | Result |
|---|---|---|---|---|
| Detailed photo, 12 MPChrome | 1.3 MB → 1.5 MB | 17 percent larger | 1.8 s | 33.3 dB likeness · 4000 × 3000 · Location removed |
| Detailed photo, 12 MPChrome | 2.5 MB → 593 kB | 77 percent smaller | 770 ms | 27.9 dB likeness · 2048 × 1536 · Location removed |
| App screenshot, 2400 by 1600Chrome | 162 kB → 82 kB | 49 percent smaller | 450 ms | 40.1 dB likeness · 2048 × 1365 |
Measured on November 7, 2026 in Google Chrome 157, on Apple M1 Pro. Times run from pressing Convert to the result being ready, with the page already loaded. Likeness is PSNR against the original: higher is closer, and above 40 dB the difference is hard to see. Every test file was generated for these measurements, none is anyone else's work, and each is described on the About page.
Converting the busy HEIC photo to JPG gave 1.5 MB. Resizing the original JPG to 2048 pixels gave 593 kB from 2.5 MB, and the 2400-pixel screenshot gave 82 kB. Resizing is the cheap way to make a JPG small: fewer pixels beat any quality setting.
Good to know
What a JPG is made of.
Understanding the loss helps you choose the setting.
Every save loses something
A JPG is lossy, so opening it, editing and saving again compresses the picture a second time. The loss is small once and adds up over many rounds. Keep an original and make copies for sharing.
Raising the quality number reduces the loss and grows the file quickly; past about 90 percent a file gets large for very little visible gain.
What JPG cannot do
It has no transparency, so a logo with a see-through background gets a solid one. It cannot hold animation. It stores 8 bits per channel, which is plenty for viewing and tight for heavy editing.
Why it lasts
It is a standard from 1992 that every program reads. When a form, an email client or a printer refuses everything else, it accepts JPG.
Choosing
When to pick it, and when not to.
A format is a trade. These are the trades this one makes.
Pick JPG when
the picture is a photograph going anywhere, to anyone.
Pick PNG instead when
the picture has sharp text, flat colour or transparency. JPG blurs hard edges.
Pick WebP or AVIF instead when
the picture goes on a web page and every kilobyte counts. They are smaller at the same look.