↔️ Image Resizer
Resize images to exact pixel dimensions or percentages. Supports JPEG, PNG, WebP, and GIF. Free online image resizer — runs in browser, no uploads to any server.
Drop image here or click to upload
PNG, JPG, WebP supported
How to Use
1
Upload your image
Drag and drop any image or click to browse. Original width and height are filled in automatically.
2
Set new dimensions
Enter target width or height in pixels. Toggle the lock icon to keep the original aspect ratio.
3
Download resized image
Choose output format (PNG/JPEG/WebP) and quality level, then click Resize and Download.
Frequently Asked Questions
Can I resize without losing quality?
Enlarging an image always reduces sharpness because you are adding pixels that did not exist. Shrinking an image generally preserves quality well. For best results when enlarging, use a dedicated AI upscaler.
What does "lock aspect ratio" mean?
When aspect ratio is locked, changing the width automatically recalculates the height (and vice versa) to keep the image proportions the same. This prevents stretching or squishing.
What output formats are supported?
You can save the resized image as PNG (lossless), JPEG (smaller file, adjustable quality), or WebP (best compression with good quality). WebP is recommended for web use.
Is there a maximum image size?
There is no hard limit, but very large images (over 10,000×10,000 pixels) may cause the browser to run slowly. The tool processes everything locally without any server.
Is my image sent to a server?
No. The entire resize operation runs in your browser using the HTML5 Canvas API. Your image never leaves your device.
完整指南：图片尺寸调整工具
为什么要调整尺寸？
一张12MP的智能手机照片（约5MB）以400px显示时，浏览器下载5MB只是为了显示400px——浪费了10-50倍的带宽。上传前调整尺寸是最基本也最有效的Web性能优化。
如何使用
- 上传图片（JPEG、PNG、WebP、GIF）。
- 输入新尺寸（像素或百分比）。
- 启用"保持比例"避免变形。
- 下载调整后的图片。
专业技巧
- 使用
srcset属性根据设备提供不同尺寸。 - 英雄图片最大宽度1920px即可满足所有屏幕。
- 调整尺寸后再用图片压缩工具进一步节省空间。