Image resizer & compressor
100% client-sideQuickly scale, downsize, convert, and compress photos or screenshots with zero quality loss. Choose custom pixel dimensions, locked aspect ratios, or popular presets with distortion-free center-crop or stretch, and export directly to WebP, JPEG, or PNG without ever uploading files to any remote server.
Resize & compression controls
Drag and drop your image here
Upload any JPG, PNG, WebP, SVG, or HEIC photo to resize dimensions and compress file size. Or press Ctrl+V to paste from clipboard.
100% private & offline
All scaling and compression runs entirely in your browser using HTML5 Canvas. Your sensitive images and photos are never uploaded or saved to remote cloud servers.
Multi-step bicubic scaling
Downscales large high-resolution photos using progressive multi-step downsampling to eliminate aliasing, jagged edges, and moiré patterns.
Smart WebP, JPEG & PNG
Dramatically shrink file sizes by up to 90% by switching to WebP or tuning JPEG quality with instant side-by-side visual comparison and savings metrics.
Crop presets & clipboard
One-click scaling (25% to 200%), aspect presets (1:1, 16:9, 4:3, 9:16) with smart center crop or stretch mode, keyboard paste (Ctrl+V), and instant clipboard copying.
Why resize and compress images locally?
Large image files slow down website loading speeds, bloat email attachments, and hit strict file-size limits on Discord, Slack, and content management systems. However, most free online image resizers require uploading your private photos, customer screenshots, or confidential graphics to third-party cloud infrastructure.
With Toolou Image Resizer, the entire resizing, sampling, cropping, and compression pipeline executes 100% inside your browser engine. There are zero file-size limitations, no rate limits or subscription paywalls, and no risk of private files being intercepted or permanently retained.
WebP vs JPEG vs PNG: Which format should you choose?
Provides the highest compression efficiency for the modern web—typically 30% smaller than JPEG at identical visual quality, while supporting transparency. Supported across all modern browsers.
The universal standard for digital photography, print, and legacy platforms. Excellent compression for complex photographic gradients, but does not support transparent backgrounds.
Lossless compression designed for UI screenshots, diagrams, logos, and illustrations with crisp text or alpha transparency. Produces pixel-perfect exports with zero compression artifacts.
Common aspect ratio & dimension guidelines
| Ratio | Common resolution | Best for |
|---|---|---|
| 1:1 Square | 1080 × 1080 px | Instagram square posts, profile pictures, avatars |
| 16:9 Landscape | 1920 × 1080 / 1280 × 720 px | YouTube thumbnails, video stills, website hero banners |
| 9:16 Portrait | 1080 × 1920 px | Instagram Stories, TikTok videos, YouTube Shorts |
| 4:3 Standard | 1600 × 1200 / 1024 × 768 px | Standard camera photos, slide presentations, tablet displays |
| 3:2 Classic | 2400 × 1600 / 1200 × 800 px | 35mm DSLR sensor format, postcard and art prints |
| 2:1 Banner | 1500 × 750 px | Twitter / X profile headers, blog post header graphics |