CodeKitHubWhat Is This Tool?
An image resizer changes the pixel dimensions of an image — different from compression, which keeps dimensions but re-encodes more efficiently. Resizing is what you need when a form demands "max 800px", an avatar must be 256×256, or a 4000px camera photo is absurd overkill for a blog column that's 700px wide.
Downscaling (making images smaller) is visually lossless and dramatically reduces file size — halving both dimensions cuts pixel count by 75%. Upscaling (enlarging) is also supported but can't invent detail: a stretched image is always somewhat soft. This tool preserves aspect ratio automatically so nothing looks squashed.
Why Use It?
- Two intuitive modes: exact pixel width (for requirements) or percentage (for quick shrinking).
- Aspect ratio locked automatically — no accidentally distorted photos.
- Also converts format on the way out if you want (JPG/PNG/WebP).
- Batch resize dozens of images with per-file downloads.
- Local and private: nothing is uploaded, no size limits.
How to Use
- Drop your images onto the box or click to choose them.
- Pick a mode: enter a target width in pixels, or a percentage.
- Optionally choose a different output format (default keeps the original).
- Each result shows the new dimensions and file size — click Download.
Example
Input
camera.jpg — 4032×3024, 3.9 MB, resized to width 1200Output
camera-1200x900.jpg — 1200×900, 260 KBThe output filename includes the new dimensions so versions never get mixed up.
Frequently Asked Questions
Will resizing reduce image quality?
Downscaling looks essentially perfect — you're removing pixels the target size can't show anyway. Upscaling beyond 100% can't add detail and produces softness; avoid it unless you must meet a minimum-size requirement.
How do I set an exact height instead of width?
Compute the width that gives your target height: width = height × (original width ÷ original height). The tool keeps aspect ratio by design — free-form width×height stretching distorts photos, which is almost never what people want.
What size should I use for the web?
Full-width hero images: 1600–1920px. Blog content images: 800–1200px. Thumbnails: 300–400px. Avatars: 256px. When unsure, match the largest size the layout will actually display, then compress.
Resize or compress — which do I need?
Both reduce file size, differently. If the dimensions are larger than needed, resize first — it's the bigger win. Then compression squeezes the remaining bytes. Our Image Compressor does quality + a max-width in one step if that fits your case.
Are my images uploaded during resizing?
No. Resizing runs on your device via the browser's canvas API. The tool works offline once the page is loaded.