How to Compress Images Online

A 4 MB photo from a modern phone is overkill for an email attachment, a Slack DM, or a website hero image. Compressing it down to a few hundred kilobytes saves bandwidth, speeds up page loads, and keeps you under attachment limits. The trick is shrinking it without leaving visible artefacts. This guide walks through quality settings, format choice, and the common mistakes that turn a clean photo into a pixelated mess.

Skip the reading: drop your photo into the Image Compressor and slide quality to 75–85. Compression runs in your browser, so the original photo never leaves your device.

Pick the right format first

• JPEG (.jpg) — best for photographs. Uses lossy compression; perfect for camera shots where soft gradients are common.
• PNG (.png) — best for logos, icons, screenshots, and any image with hard edges or transparency. Lossless: pixels are preserved exactly.
• WebP (.webp) — modern format that beats both. Roughly 25–35% smaller than JPEG at the same quality, and supports both lossy and lossless modes plus transparency. Supported in every modern browser.

Choose a quality level

JPEG and WebP let you trade visual fidelity for file size with a single number, usually 0–100. A few sensible defaults:

• Hero images, print-ready photos: quality 90+ — minimal compression, sharpest detail.
• Standard web photos: quality 75–85 — the sweet spot. Halves the file size with no perceptible loss for most viewers.
• Thumbnails and chat avatars: quality 60–70 — small file sizes; small display sizes hide most artefacts.
• Avoid: below 50 unless you specifically want a "lo-fi" look. JPEG blockiness becomes obvious under 50.

A worked example

A 4032 × 3024 photo straight off an iPhone, stored as a 4.1 MB JPEG, processed through the Image Compressor:

• Quality 95 (JPEG): ~2.4 MB — barely smaller, indistinguishable from original.
• Quality 85 (JPEG): ~1.0 MB — still indistinguishable on a typical phone or laptop screen.
• Quality 75 (JPEG): ~700 KB — slight softening visible on close inspection.
• Quality 80 (WebP): ~600 KB — looks like the quality-85 JPEG but smaller again.
• Quality 60 (JPEG): ~400 KB — visible blockiness on smooth gradients.

Common mistakes

• Re-compressing a JPEG over and over. Each save throws away more detail. Always compress from the original.
• Saving a logo or screenshot as JPEG. Sharp edges show JPEG ringing artefacts. Use PNG (or lossless WebP) for graphics.
• Compressing a PNG photograph. PNG can't compress photos as well as JPEG. Convert photographs to JPEG or WebP first.
• Forgetting to resize. A 4032-wide image displayed at 800px on a website is wasteful. Resize first using the Image Resizer, then compress.

Resize before you compress

Compression makes a file smaller; resizing makes the picture physically smaller in pixels. They're separate operations, and combining them has the biggest impact. Drop a photo into the Image Resizer, set the width to whatever your destination needs (1200 px is a good blog/social default), then run the result through the Image Compressor. The combined effect is usually a 90%+ size reduction.

Privacy

Both tools run entirely in your browser using the HTML5 Canvas. The photo is never uploaded to a server, which matters when you're handling private images — passport scans, kids' photos, draft product shots, anything you'd rather not pass through a third-party service.

Last updated: May 2026.

Try it now

Open the Image Compressor for a quality slider with live size estimates, or jump to the Image Resizer if your photos are bigger than they need to be.