Source: https://mactoolbox.app/glossary/jpeg

# What is JPEG?

By Nikhil Barik · Published November 3, 2026

## Quick answer

JPEG, also written JPG, is the most widely supported photo format. It uses lossy compression to make small files and has no transparency.

## What it is

JPEG removes detail that is hard to see to save space. A lower quality setting makes a smaller file with more visible artifacts.

## Why it matters on a Mac

It opens in every app and website, so it is the safe format for sharing photos. Resaving a JPEG repeatedly can add more loss.

## How to check or change it on macOS

In Preview, choose File > Export, pick JPEG and use the Quality slider to see the size change.

## How Toolbox handles it

Convert Images turns HEIC, PNG and other formats into JPEG. Compress Images reduces size with Low, Medium or High quality and can save as JPEG or HEIC, in batches and on your Mac.

## Frequently asked questions

**Are JPG and JPEG different?**

No. They are the same format with different extensions.

**Does JPEG support transparency?**

No. Use PNG, WebP or HEIC.

**What quality should I use?**

Medium to high suits most photos.

## Tools mentioned

- [**Convert Images**: Save photos as JPEG, PNG, HEIC, TIFF or WebP.](https://mactoolbox.app/heic-to-jpg-mac)
- [**Compress Images**: Make photos smaller without visible loss in quality.](https://mactoolbox.app/compress-images-mac)

## Keep reading

- [Convert Images](https://mactoolbox.app/heic-to-jpg-mac)
- [Compress Images](https://mactoolbox.app/compress-images-mac)
- [HEIC](https://mactoolbox.app/glossary/heic)
- [Lossless vs lossy](https://mactoolbox.app/glossary/lossless-vs-lossy)