Compress Images Online

How to reduce image size

To reduce image size, drop your photos onto the panel above and press Compress. A photo straight off a phone runs 3–8 MB; on the Balanced preset the same photo lands between 300 and 900 KB and looks identical on screen.

The controls read in the order you need them. Compression stays on By quality unless you have a specific byte budget, and Balanced at quality 75 suits almost everything — the slider underneath exists for the times it doesn't.

Output format decides which encoder does the work. Auto keeps every file in its own format, so a PNG screenshot stays lossless while a JPEG photo stays JPEG; change it only when you want a smaller file than the original format can give you.

Once the run finishes, drag the divider on the preview to compare the compressed pixels against the original at full resolution. It is worth not skipping — it is the only way to tell whether a setting that saved 80% cost you anything you care about.

Reduce image size in KB

To reduce image size in KB, switch Compression from By quality to To a file size and name your limit — 100 KB, 50 KB, 20 KB, or any figure the form demands. Every image is then compressed to fit under that exact size.

Guessing with the quality slider is genuinely hard rather than merely tedious. Quality is not a size setting, and two photos saved at quality 75 can differ in file size by a factor of ten depending on how much detail they hold: a flat studio portrait compresses far smaller than a photo of foliage. The number that lands one image on 100 KB overshoots badly for the next.

Naming a target hands that search to the encoder. Each image is run several times and the highest quality that still fits is kept. If even heavy compression cannot get there, the dimensions come down and the search runs again — a slightly smaller image that is sharp beats a full-size one dissolved into artefacts.

Most people arrive here calling this resizing. Resizing changes an image's dimensions; compressing changes how many bytes those dimensions cost to store. If a form specifies both, resize first and compress the result.

How to compress an image without losing quality

To compress an image without losing visible quality, stay at quality 75 or above — the Balanced preset. At that setting a photograph typically drops 60–80% in size with no difference you can see on screen, which is what photographers mean by visually lossless.

The useful range is much narrower than the 1–100 scale implies. Below 50, artefacts show as blocky patches and haloing around edges; above 90, the file grows steeply for detail almost nobody can see on a screen. That leaves 60 to 90 as the range where the decision actually lives, which is why the four presets all sit inside it.

Screenshots, logos, and illustrations are the exception, and the presets will mislead you on them. Flat colour makes lossy artefacts obvious exactly where they hurt most, around text and hard edges. Keep those as PNG, where compression is lossless, or stay above quality 90.

Compress JPEG, PNG, or GIF

Before reaching for Aggressive, look at the Output format control: at matched visual quality the format usually saves more than the quality dial can.

AVIF encodes a photograph to roughly half the size of a JPG that looks the same, and WebP lands between the two. That beats moving from quality 75 down to 60, and unlike the quality drop it costs nothing visible.

Format also decides whether compression costs you anything at all. Compressing JPEG is lossy, so every save discards a little more. Compressing PNG is mathematically lossless. Compressing GIF converts to WebP, since browsers cannot write GIF.

Which to pick comes down to where the file is going. Keep JPG for anything emailed, printed, or opened in desktop software, where universal support matters more than bytes. Use WebP for a website. Choose AVIF when page weight is the priority and slower encoding is acceptable.

Compress images for web and email

For a website, convert to WebP at quality 75 and keep images under about 200 KB. For email, stay in JPG and aim under 1 MB per attachment so the message survives strict gateways.

The two pull in opposite directions: a website rewards the smallest file, while email rewards the most compatible one, because you cannot know what will open it. Print is a third case — leave it at Light or higher, since paper resolves detail a screen never shows and artefacts invisible on a monitor can appear in ink.

The encoders behind the output

This compressor runs the same codec builds as Squoosh, Google Chrome Labs' image tool, compiled to WebAssembly and vendored into the site.

JPG goes through MozJPEG with trellis quantisation and progressive output, WebP through libwebp, AVIF through libavif, and PNG through OxiPNG.

That matters because most in-browser compressors redraw your image onto a canvas and re-save it, handing the encoding to whatever the browser does by default. Running the real codecs means the output matches what a desktop tool would produce.