Compress an Image Online

Big image files slow down websites, fill up inboxes, and get rejected by upload forms with a size cap. Compressing fixes all three: it makes the file dramatically smaller while keeping the picture looking the same. This guide explains why images get big, how compression actually works, and how to get the smallest file that still looks great — using the free compressor at the top of this page, which runs entirely in your browser.

Why image files get big (dimensions vs compression)

Two separate things decide an image’s file size:

1. Pixel dimensions — how many pixels wide and tall it is. A modern phone shoots photos at 4000×3000 (12 megapixels) or more. That’s a lot of pixels, and most uses (a website, a profile photo, an email) need far fewer.
2. Compression — how efficiently those pixels are stored. The same photo can be a 6 MB file or a 400 KB file depending on the format and quality setting.

The biggest mistake people make is trying to fix size with compression alone while leaving a giant image at full dimensions. If a photo only needs to display at 1200 pixels wide, resizing it first does more than any quality slider. Compression then squeezes what’s left.

Lossy vs lossless

• Lossy (JPEG, WebP): throws away detail your eye is unlikely to notice, in exchange for much smaller files. You control how aggressive it is with a quality setting. This is what you want for photographs.
• Lossless (PNG): keeps every pixel exactly. Great for logos, screenshots, and sharp-edged graphics, but it can’t shrink a photo much because it isn’t allowed to discard anything.

This is the key reason a PNG photo “won’t compress”: PNG is doing its job perfectly — it just isn’t the right tool for photographic content. Convert it to WebP or JPEG instead.

JPEG vs WebP

For the same visible quality, WebP files are usually 25–35% smaller than JPEG, and WebP also supports transparency. The trade-off is compatibility: every program on earth opens a JPEG, while a few very old tools still don’t accept WebP.

A simple rule:

• WebP — for anything that will live on the modern web, when you control where it’s used.
• JPEG — for maximum compatibility (email, printing, old upload forms).
• PNG — keep it as PNG only for graphics/transparency; convert photos away from PNG.

The tool’s Auto format keeps JPEGs as JPEG and converts PNGs to WebP, which is the right default most of the time.

Resize first, then compress

If your image is bigger than it needs to be on screen, set a Max dimension before compressing. Capping the longest edge to, say, 1600 or 1920 pixels often cuts the file by more than half before quality even comes into play — and at normal viewing sizes you won’t see a difference.

Quality sweet spots

For lossy formats, quality is a number from low to high. You rarely need the maximum:

• 90–100 — visually lossless; larger files. Use when the image must be pristine.
• 75–85 — the sweet spot for photos. Big size savings, no visible loss for most images.
• 60–75 — noticeably smaller; fine for thumbnails and backgrounds where slight softening is acceptable.
• Below 60 — visible artefacts (blocky skies, fuzzy text). Use only when size matters more than looks.

Start at 80 and only move it if you need to. Flat areas like skies and skin show compression first, so check those when judging quality.

How to compress an image (step by step)

1. Open your image — drag it onto the tool above, click Choose image, or paste from the clipboard.
2. Pick a mode — Quality (set a quality level) or Target size (aim for an exact KB).
3. Choose a format — leave it on Auto, or force WebP/JPEG.
4. Resize (optional) — cap the longest edge in pixels for oversized photos.
5. Read the result — the before → after panel shows the new size and the percentage saved.
6. Download — your compressed image saves straight to your device.

Hitting an exact file size

Upload forms often say “max 2 MB” or “under 500 KB.” Switch to Target size mode and type the number in KB. The tool searches different quality levels (and reduces dimensions if it has to) to land at or just under your target, then tells you the exact size it achieved. No more guess-and-check.

Is it safe? Where does the compression happen?

The compression itself runs in your browser — the new file is created on your device. As a bonus, re-encoding through the canvas strips EXIF metadata, including any GPS location your camera embedded, so the compressed file is cleaner to share.

How any data associated with this tool is handled is described in our privacy policy. If you’re working with something highly sensitive, an offline desktop tool is always the most private option.

Web vs print

• For the web, smaller is better: resize to the display size, prefer WebP, and aim for quality around 80. Faster pages rank better and waste less data.
• For print, keep more pixels and use higher quality — print needs roughly 300 pixels per inch, so a 4×6 photo wants about 1200×1800 pixels. Don’t over-compress images headed for paper.

Resize to what you need, convert photos to WebP or JPEG, and keep quality around 80 — with those three habits the tool above turns bloated images into lean, shareable files in a second.