Budgeting Page Weight & Core Web Vitals
Estimate how much bandwidth you will save by scaling hero banners from 3840px down to 1600px and switching from JPG to WebP.
Image Size Calculator
Plan your image exports with mathematical precision before processing large batches. Enter your source pixel width and height, select a scaling percentage, and compare the resulting pixel dimensions, total megapixels, aspect ratio, and estimated file weight across JPG, PNG, and WebP.
- Output dimensions
- 1920 × 1080 px
- Total pixels
- 2.07 MP
- Aspect ratio
- 1.778 : 1
- Estimated file size
- 506.3 KB
File size is an estimate. Real results depend on the detail in your image and the encoder used.
How to Use the Image Size Calculator
- 1
Enter your original image width and height in pixels (for example, 4000 × 3000 px from a 12MP camera).
- 2
Adjust the Scale Percentage slider or click a quick preset (25%, 50%, 75%, 100%, or 200%) to test proportional resizing.
- 3
Select your target export format (JPG, WebP, or PNG) and quality level to model compression efficiency.
- 4
Review the calculated output dimensions, megapixel count, simplified aspect ratio, and estimated KB/MB file size.
Practical Use Cases
Meeting Strict Portal Dimension & KB Limits
Find the exact scaling factor needed to bring a high-resolution camera photo under government exam or visa portal limits (such as under 200 KB).
Checking Megapixel Counts After Cropping
Verify total megapixels and aspect ratios when downscaling master files for client web delivery vs archival storage.
Image Size Calculator Features
Real-Time Proportional Scaling
Instantly computes scaled width and height from 10% thumbnails up to 200% enlargements.
Multi-Format Byte Estimation
Compare projected file sizes across JPG, modern WebP, and lossless PNG at different quality settings.
Megapixel & Aspect Ratio Readout
Displays total megapixels (MP) and automatically simplifies the width-to-height ratio.
Zero Upload Required
Pure client-side mathematical utility — plan dimensions without needing to upload files.
Mobile & Desktop Friendly
Clean numeric inputs and one-tap percentage presets for rapid testing.
100% Free & Private
Runs locally in your browser with no sign-up or usage limits.
Technical Specifications & Best Practices
- ✓Because scaling affects both width and height, a 50% dimension scale reduces total pixels and file weight by approximately 75%.
- ✓WebP at 80%–85% quality typically produces files 25% to 35% smaller than JPG at equivalent visual sharpness.
- ✓Actual exported file sizes vary based on scene complexity: flat vector-style graphics compress much smaller than noisy high-ISO photographs.
- ✓To physically resize and compress your image files after calculating, jump directly to our Resize Image or Compress Image tool.