Image Resize Calculator
Free online image resize calculator. No sign-up, no installation. Runs entirely in your browser.
Original Dimensions
New Dimensions
Quick Presets
Batch Size Table
Common sizes scaled from your original image (maintaining aspect ratio):
| Preset Name | Dimensions | Scale % | JPEG Est. |
|---|---|---|---|
| Enter original dimensions to see batch table | |||
What is an Image Resize Calculator?
An image resize calculator helps you determine new image dimensions while maintaining aspect ratio. It prevents distortion by automatically calculating how width and height should scale proportionally. This tool shows you the scale percentage, estimated file sizes for different formats (JPEG, PNG, WebP), and how your image scales to popular preset sizes used across web and social media platforms.
How to Use the Image Resize Calculator
- Enter your original image width and height in pixels.
- Keep "Lock aspect ratio" checked to maintain proportions automatically.
- Enter either a new width or new height—the other will auto-fill instantly.
- View the scale percentage and estimated file sizes for JPEG format.
- Click any Quick Preset button to jump to common sizes (thumbnail, social media, HD, 4K).
- Check the Batch Size Table to see how your image scales to multiple standard dimensions.
Common Use Cases
- Web Optimization: Resize photos for faster loading and better page performance.
- Social Media: Calculate correct dimensions for Instagram, Facebook, Twitter, LinkedIn, and TikTok.
- Email Marketing: Prepare images that display perfectly in email clients on all devices.
- Content Management: Plan batch image resizing before processing hundreds of photos.
- Responsive Design: Calculate mobile vs. desktop image sizes for your website.
- Print Preparation: Understand pixel-to-physical dimensions for print projects.
Frequently Asked Questions
What is aspect ratio and why should I lock it?
Aspect ratio is the proportional relationship between width and height (e.g., 16:9, 4:3, 1:1). Locking it prevents distortion when resizing. If you change the width, the height automatically adjusts to maintain the original proportions. Unlock it only if you intentionally want to crop or stretch the image.
How accurate are the file size estimates?
Estimates use average compression ratios: JPEG ~0.12 bytes/pixel, PNG ~3–4 bytes/pixel, WebP ~0.10 bytes/pixel. Actual file sizes depend on image content, color complexity, and compression settings. Use these estimates for planning, not exact predictions.
Does this tool actually resize my image?
No. This calculator only plans and calculates dimensions. To actually resize an image, use photo editors (Photoshop, GIMP), online tools (Squoosh, Cloudinary), or scripts (ImageMagick). This tool helps you decide the target dimensions first.
What's the difference between JPEG, PNG, and WebP?
JPEG: Best for photos; lossy compression; smaller files; no transparency. PNG: Best for graphics and icons; lossless; supports transparency; larger files. WebP: Modern format; smaller than JPEG at same quality; good web performance.
How do I calculate print dimensions from pixels?
Divide pixels by DPI (dots per inch). For example: 1920 pixels ÷ 300 DPI = 6.4 inches wide. Web graphics typically use 72 DPI, while print usually requires 150–300 DPI. Higher DPI = sharper print quality.
Is my data private on this calculator?
Yes. All calculations happen locally in your browser. No data is sent to any server, and your image information never leaves your device. Your privacy is completely protected.