Image Resizer
Resize images to exact dimensions. Includes presets for social media covers and ID photos.
Drop image files here
or
Supported formats: JPEG, PNG, WebP, GIF, BMP, HEIC — multiple files supported
What Is Image Resizing?
Image resizing is an online tool that changes the width and height of JPG, PNG, and WebP images. It's useful for standardizing images for websites, creating profile pictures for social media, and adjusting resolution for print — wherever you need to fit images to specific dimensions.
sakutto.ai's image resizer runs entirely in your browser — your images are never uploaded to any server. It supports both pixel and percentage sizing, with the option to maintain the original aspect ratio.
Whether you need to standardize product images for an e-commerce site, optimize blog images, or resize photos for a presentation, this tool handles it quickly. Batch processing is supported, and it's free with no sign-up required.
How to Resize Images
- Drag & drop image files or use the file picker to add them
- Choose a resize method (pixel dimensions, percentage, or social media preset)
- Optionally adjust the fit mode or output format
- Click "Start Resize" to convert and download
Features of sakutto's Image Resizer
- Privacy Protection
- Images are never uploaded to a server — all processing happens entirely in your browser
- Social Media Presets
- One-click presets for 16+ platforms including LINE, X/Twitter, Instagram, Facebook, YouTube, and TikTok
- Three Resize Modes
- Choose from pixel dimensions, percentage scaling, or social media presets
- Fit Modes
- Four fit options: Fit, Cover, Stretch, and Padding
- Format Conversion
- Convert to JPEG, PNG, or WebP
- Batch Processing
- Resize multiple files at once and download them as a ZIP
Use Cases for Image Resizing
Social Media Posts
Resize images to the recommended dimensions for LINE, X/Twitter, Instagram, YouTube, TikTok, and more. Presets make it effortless.
Websites & Blogs
Resize OGP images and thumbnails to specific dimensions. Also helps improve page load speed.
Email Attachments
Shrink oversized images to meet email attachment size limits.
ID Photos & Print
Presets for passport (35x45 mm), driver's license (24x30 mm), and resume photos (30x40 mm). Also supports A4 (300 DPI) for print-ready resizing.
Why Image Resizer on sakutto is safe
Many online tools upload your files to external servers for processing. This tool never sends your image files to any server — everything is processed entirely in your browser.
* Some AI-powered tools require server-side processing. Tools that send data to a server will always notify you beforehand.
| Comparison | Typical online tools | sakutto |
|---|---|---|
| Where data is sent | Uploaded to external servers | Nowhere — processed in your browser |
| Data leak risk | Risk during transfer and server storage | No risk — no network transfer occurs |
| External traffic | File data travels over the internet | No file data appears in network logs |
| Offline use | Not possible (server required) | Works offline after initial load |
How browser-based processing works
- WebAssembly (WASM): Processes image files in your browser at near-native speed. No server communication occurs.
- Web Workers: Runs on a background thread separate from the main thread, so your browser stays responsive during processing.
- After processing, your browser automatically frees the data from memory. No image files remains outside your device.
For IT security teams: How to verify
You can verify that sakutto never sends your image files externally by checking the Network tab in your browser's DevTools while using the tool. You'll see that no requests involving your image files are made. This can also serve as documentation for your IT security team.
Frequently Asked Questions
Are my files uploaded to a server?
No. All processing is done entirely in your browser — your image files are never sent to any external server. You can safely use this tool even with ID photos containing personal information.
What image formats are supported?
JPEG, PNG, WebP, GIF, BMP, and HEIC (iPhone photos) are supported. You can also convert to JPEG, PNG, or WebP when resizing.
Can I maintain the aspect ratio?
Yes. In pixel-dimension mode, the aspect ratio lock feature automatically calculates the other dimension when you enter either width or height.
How many files can I resize at once?
The free version supports up to 5 files per batch (max 10 MB each). The Pro plan (coming soon) will remove these limits.
Will resizing reduce image quality?
PNG output is lossless. For JPEG and WebP, you can adjust quality with the slider — the default is 85% for high quality. Downscaling rarely causes noticeable quality loss, but upscaling may result in some degradation.
I don't know the right size for social media
The preset feature lets you instantly select recommended sizes for major platforms including LINE, X/Twitter, Instagram, Facebook, YouTube, and TikTok. Presets for Instagram vertical posts, YouTube channel banners, and more are also included.
Which size should I use for ID photos?
We provide ID photo presets: passport is 35x45 mm (413x531 px), driver's license is 24x30 mm (283x354 px), and resume photos are 30x40 mm (354x472 px). All are output at 300 DPI resolution.
What's the best size for TikTok posts?
The recommended size for TikTok posts is 1080x1920 px (9:16 vertical). Simply select the "TikTok Post" preset and you're done.
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