Image Compressor

Large images are the single biggest drag on page speed.

A modern phone photo is 4-8 MB straight from the camera, an eCommerce listing might stack a dozen of them on one page, and every extra megabyte costs real seconds on mobile networks. This image compressor shrinks JPEG, PNG, and WebP files to a fraction of their original size without visibly changing how they look.

Drop up to 20 images onto the tool, adjust quality and maximum dimensions if you want, and click Compress All. You get an instant before / after size comparison for each file plus a one-click ZIP download of the whole batch. Typical savings are 50-70% for photos and 30-60% for graphics at default settings.

Everything runs in your browser using the Canvas API — nothing is uploaded to any server. That makes the tool faster than cloud-based compressors (no upload / download round-trip) and safer for sensitive content like ID scans, draft designs, client photos, or internal screenshots.

How Image Compression Works

Compression reduces the number of bits needed to describe an image. There are two families of techniques.

Lossless compression (PNG, WebP lossless, GIF) rewrites pixel data more efficiently without throwing any of it away. Decoding produces a bit-perfect copy of the original. Lossless gains come from exploiting redundancy — long runs of the same color, repeated patterns, or predictable gradients. PNG uses DEFLATE, the same algorithm behind ZIP. Savings are modest for photographs (where every pixel is slightly different) but dramatic for flat graphics and screenshots.

Lossy compression (JPEG, WebP, AVIF) actively discards information the human eye is unlikely to notice. JPEG splits the image into 8×8 blocks, applies a discrete cosine transform (DCT), and quantizes the resulting frequency coefficients. High-frequency detail — fine textures, subtle gradients — is quantized more aggressively because people pay less attention to it. The quality slider controls how aggressive that quantization is: quality 1.0 keeps nearly everything, quality 0.5 throws away a lot, and quality 0.8 is the sweet spot where artifacts are almost always invisible.

JPEG vs PNG vs WebP vs AVIF

JPEG is the right choice for photographs: camera captures, product shots, scenery, portraits. It handles smooth tonal gradients well and compresses them aggressively. JPEG does not support transparency and introduces visible blocking artifacts on hard edges, so it is a poor fit for logos, screenshots, or line art.

PNG is the right choice for graphics with flat colors, transparency, or hard edges: logos, icons, diagrams, screenshots of text. PNG is lossless, so re-saving a PNG ten times produces an identical file. Trying to PNG-compress a photograph usually produces a huge file that is no smaller than the original JPEG.

WebP is a modern format supported by every major browser since 2020. It offers both lossy and lossless modes and typically produces files 25-35% smaller than equivalent-quality JPEG or PNG. WebP is a strong default if your audience uses modern browsers.

AVIF (not used by this tool but worth knowing) is the newest of the four. It compresses even better than WebP — often 50% smaller than JPEG — but encoding is slow and browser support, while good, lags WebP by a few years.

Quality Slider Explained

Quality is a single number between 0.1 and 1.0 that controls how aggressively a lossy encoder throws away detail.

• 0.9-1.0: near-original quality. Savings are modest (10-30%) and the files still look pristine under close inspection. Use this for hero images or product photos where quality matters more than size.
• 0.75-0.85: the default zone. Savings of 40-70% with no visible difference at normal viewing distance. This is where 95% of web images live. Our default of 0.8 is a safe starting point.
• 0.5-0.7: visible but subtle quality loss on close inspection. Good for thumbnails or background decoration where the image is small on screen.
• Below 0.5: obvious blocking and color banding. Avoid unless bandwidth is critical.

Higher quality settings with the same input image will always produce larger files. If you are unsure, start at 0.8 and only reduce if the result is too big.

Resizing vs Compression

Dimension reduction and quality compression are different levers, and combining them is usually more effective than using either alone. A 4000×3000 pixel photo taken by a phone displays in a 600-pixel-wide blog post — you are wasting roughly 98% of the pixels. Scaling that photo to 1920 pixels wide before encoding makes the JPEG quantizer’s job easier, reduces file size disproportionately, and is invisible to readers because the image is displayed smaller than its source resolution anyway.

This tool’s default max dimension is 1920 pixels, which comfortably supports full-HD displays and most retina layouts. Drop it to 1200 for content-area images, 800 for thumbnails, or raise it to 2560 if you need 4K / 2x retina quality.

Privacy: Nothing Uploaded

Cloud-based image compressors upload your file to a server, run the compression there, then send the result back. That flow has three problems. First, it is slow — upload is usually the bottleneck, especially on mobile networks. Second, the server operator has a copy of your image. Third, server-side tools can silently log, analyze, or retain your content.

This tool runs entirely in the browser using the Canvas API. When you select a file, it is read into memory as a JavaScript Blob, drawn onto an off-screen canvas, re-encoded via the browser’s built-in JPEG / PNG / WebP encoders, and handed back to you as a downloadable Blob. No HTTP request is made, no tracker fires, no copy leaves the tab. You can verify this by opening the browser’s Network tab while compressing — there will be no outgoing requests.

Typical Compression Ratios

Results depend heavily on the input, but here are realistic expectations at quality 0.8 and default dimensions:

• Phone photos (5-8 MB JPEG straight from camera): 70-85% smaller. An 8 MB vacation photo becomes 1.2-2 MB.
• DSLR / mirrorless JPEGs (10-25 MB): 80-90% smaller. Often the single biggest win.
• Already-compressed web JPEGs (200-800 KB): 20-40% further savings. Lower quality settings help more here.
• PNG screenshots of text or UI: use PNG output (lossless) and 30-60% savings is common. If the screenshot contains photo content, converting to JPEG often saves 80%+.
• PNG logos and icons: 10-40% savings from PNG re-optimization. For single-color or flat designs, consider SVG instead.
• WebP output on any of the above: add another 20-30% savings over the same quality JPEG.

Some files are already optimally compressed (hand-tuned JPEGs from a professional workflow, for example). If the compressor can’t improve on that, you will see a small negative percentage — a "+2%" badge means the compressed file is slightly larger and you should keep the original.

Mobile and SEO Impact

Images are the single largest contributor to page weight on the modern web, averaging around 50% of total bytes according to the HTTP Archive. Compressing them directly improves two Core Web Vitals metrics that Google uses for ranking.

Largest Contentful Paint (LCP) measures when the biggest above-the-fold element renders. On image-heavy pages — eCommerce, news, blogs — that is usually an image. Cutting image weight in half typically shaves 1-3 seconds off LCP on mobile.

Cumulative Layout Shift (CLS) is less about file size, but compressed images load sooner, so placeholder-to-final image swaps happen faster and feel less jarring.

Beyond Core Web Vitals, smaller images mean lower bandwidth bills for you, less mobile data for your users, and a better experience on flaky networks. Combine compression with modern delivery (srcset, lazy loading, WebP with JPEG fallback) for the best results.

How to Use

1. Drop or select images — drag files onto the tool or click the drop zone. Up to 20 files, 10 MB each.
2. Adjust settings (optional) — open the Compression Settings panel to change quality, max dimension, or output format. Defaults are good for 90% of cases.
3. Compress All — the tool processes files in sequence, showing original size, compressed size, and percentage reduction for each.
4. Download — click Download on any row for a single file, or Download All as ZIP to grab the whole batch in one archive.

Frequently Asked Questions

Is my image uploaded anywhere?

No. Compression happens entirely in your browser using the Canvas API. You can verify this by opening the Network tab in your browser’s developer tools while compressing — no outgoing requests are made. This makes the tool safe for sensitive content like client photos, ID documents, or unreleased designs.

What is the maximum file size?

10 MB per image, and up to 20 images at once. These limits protect your browser from running out of memory on low-end devices. For larger files, compress them one at a time or reduce the dimensions first with a desktop tool.

Why is my PNG not any smaller after compression?

PNG is a lossless format. If your source PNG was already optimized (by Photoshop, TinyPNG, or another tool), there may be no further savings available. Try converting to JPEG if the image is photographic, or to WebP for the best modern compression.

Should I use WebP?

Yes, if your audience uses modern browsers (which is 96%+ globally as of 2026). WebP produces 25-35% smaller files than JPEG at the same visual quality. For maximum compatibility with older browsers or email clients, stick with JPEG or PNG.

What quality should I choose?

Start with 0.8 — the default. At this setting, most people cannot tell the compressed image from the original at normal viewing distance, and you will typically save 50-70% of the file size. Reduce to 0.6-0.7 for thumbnails where tiny quality loss does not matter; raise to 0.9-0.95 for hero images.

Can I compress multiple images at once?

Yes. Drop up to 20 files onto the tool at once, click Compress All, and download the results individually or as a single ZIP archive. Each file shows its own original / compressed sizes and percentage reduction.

Does this work on mobile?

Yes. The compressor runs on any modern mobile browser (Safari on iOS 14+, Chrome on Android 8+). Performance depends on your phone — very large images on budget devices may take a few seconds each. The 10 MB file limit is intentionally conservative to avoid crashing mobile browsers.

Data accurate as of: April 2026