Free Image Resizer
Change image dimensions effortlessly. Resize by exact pixels or percentage. Maintain perfect aspect ratios automatically. Process multiple images at once. 100% free, no registration required.
Resize Images
JPG, PNG, WebP supported
When to Resize Images
Common scenarios where image resizing is essential
Web Optimization
Large images slow down websites dramatically. Resize to optimal dimensions before uploading. A 4000×3000px image displayed at 800px width wastes 95% of bandwidth and loading time. Proper resizing improves page speed and SEO.
Social Media
Every platform has specific image size requirements. Instagram posts: 1080×1080px, Facebook covers: 820×312px, Twitter headers: 1500×500px. Resize to exact dimensions for perfect display without cropping or distortion.
Email Attachments
Most email servers limit attachment sizes to 10-25MB. A single high-resolution photo can be 5-10MB. Resize to 50% or specify smaller dimensions to fit multiple images in one email without hitting size limits.
Print Preparation
Print requires specific DPI and dimensions. For 4×6" photo at 300 DPI, you need exactly 1200×1800px. Resize to exact print dimensions to avoid unexpected cropping or quality issues at the print shop.
Profile Pictures & Avatars
Gaming platforms, forums, and professional networks require small, square avatars. Discord: 128×128px, LinkedIn: 400×400px, Steam: 184×184px. Resize and crop to exact specifications for perfect display.
Thumbnail Creation
Video thumbnails, product previews, and image galleries need optimized thumbnails. YouTube thumbnails: 1280×720px, product thumbnails: 300-500px. Small, fast-loading thumbnails improve user experience and performance.
How Image Resizing Works
Understanding the technology behind quality image resizing
Image Loading
Your browser reads the image file and decodes it into a pixel array. The original dimensions and aspect ratio are detected automatically.
Dimension Calculation
Based on your input (pixels or percentage), the tool calculates new dimensions. If you specify width, height is calculated automatically to maintain aspect ratio.
High-Quality Resampling
Advanced interpolation algorithms (bilinear or bicubic) resample the image. Upscaling adds new pixels, downscaling removes them intelligently to preserve clarity.
Export
The resized image is encoded in your chosen format and downloaded. All processing happens locally — your images never leave your device.
Complete Resizing Guide
📏 Resize by Pixels (Exact Dimensions)
When to use: When you need exact dimensions for specific platforms or requirements.
How it works: Enter exact width or height in pixels. The tool automatically calculates the other dimension to maintain aspect ratio (unless you unlock the ratio).
Example use cases:
- Social media cover images (exact size required)
- Banner ads (specific pixel requirements)
- Profile pictures (square dimensions needed)
- Responsive web images (specific breakpoints)
Pro tip: Always specify the most important dimension. For landscape images, set width; for portraits, set height.
📊 Resize by Percentage (Proportional Scaling)
When to use: When you want to quickly scale images proportionally without knowing exact dimensions.
How it works: Enter a percentage (e.g., 50% for half size, 200% for double). Both width and height scale proportionally.
Example use cases:
- Quick size reduction (75% or 50% for faster loading)
- Batch processing multiple images uniformly
- Creating multiple size variants (thumbnail: 25%, medium: 50%, large: 100%)
- Reducing file size without calculating pixels
Pro tip: 75% reduces file size by ~45%, 50% reduces by ~75%. Great for quick optimization!
🔒 Aspect Ratio Locking
Locked (Default): Maintains original proportions. If you change width, height adjusts automatically. Prevents distortion and stretching. Use this 95% of the time.
Unlocked (Advanced): Allows independent width and height changes. Can create distorted images (wider or taller than original proportions). Useful for:
- Creating intentionally stretched effects
- Fitting into specific containers (e.g., 16:9 video from 4:3 photo)
- Panoramic or ultra-wide formats
Warning: Unlocking aspect ratio can make images look unnatural. Only use when you specifically need distorted proportions.
⬆️ Upscaling vs ⬇️ Downscaling
Downscaling (Making Smaller): Always produces good results. The algorithm discards pixels intelligently, preserving important details. Use for optimization and faster loading.
Upscaling (Making Larger): Cannot add detail that doesn't exist. The algorithm creates new pixels by interpolation (guessing). Results:
- 110-150%: Usually acceptable, slight softness
- 150-200%: Noticeable blur and pixelation
- 200%+: Poor quality, very blurry
Best practice: Always capture/create images at the largest size you'll need. Downscaling is always better than upscaling.
Common Image Dimensions Reference
Quick reference for popular platform requirements
📱 Social Media
- Instagram Post (Square): 1080×1080px
- Instagram Story: 1080×1920px (9:16)
- Instagram Reels: 1080×1920px
- Facebook Post: 1200×630px
- Facebook Cover: 820×312px
- Twitter Post: 1200×675px
- Twitter Header: 1500×500px
- LinkedIn Post: 1200×627px
- LinkedIn Cover: 1584×396px
- Pinterest Pin: 1000×1500px (2:3)
🖼️ Web & Display
- Full HD: 1920×1080px
- 4K/UHD: 3840×2160px
- Website Hero: 1920×1080px
- Blog Featured Image: 1200×628px
- Thumbnail: 300×300px
- Medium Preview: 600×400px
- Large Display: 1400×900px
🎮 Avatars & Icons
- Discord Avatar: 128×128px
- Twitter Profile: 400×400px
- LinkedIn Profile: 400×400px
- Facebook Profile: 180×180px
- Steam Avatar: 184×184px
- Reddit Icon: 256×256px
- Favicon: 32×32px or 64×64px
📹 Video Thumbnails
- YouTube Thumbnail: 1280×720px
- Vimeo Thumbnail: 1280×720px
- Twitch Thumbnail: 1280×720px
- TikTok Cover: 1080×1920px
🖨️ Print Sizes (at 300 DPI)
- 4×6" Photo: 1200×1800px
- 5×7" Photo: 1500×2100px
- 8×10" Photo: 2400×3000px
- A4 (8.3×11.7"): 2480×3508px
- Letter (8.5×11"): 2550×3300px
📧 Email & Newsletters
- Email Header: 600×200px
- Email Banner: 600×300px
- Email Body Image: 600px width (variable height)
Frequently Asked Questions
Is this image resizer completely free?
Yes, 100% free with no limitations. Resize unlimited images, no registration required, no hidden fees, no premium tiers. All processing happens in your browser, so we have no server costs to pass on to you.
Will resizing reduce image quality?
Downscaling (making smaller): Minimal quality loss. Modern resampling algorithms preserve sharpness and detail very well. The result usually looks excellent.
Upscaling (making larger): Cannot add detail that doesn't exist. Slight upscaling (110-150%) is usually fine, but larger increases will show blur and pixelation. Always work from the largest possible source image.
What's the difference between pixels and percentage?
Pixels: Exact dimensions. Use when you need specific sizes (e.g., "1920×1080px" for a website header).
Percentage: Proportional scaling. Use for quick resizing without calculating (e.g., "50%" to halve the size). Easier for batch processing multiple images uniformly.
Can I resize multiple images at once?
Yes! Upload multiple images, set your desired dimensions or percentage, and all images will be resized with the same settings. Perfect for processing photo albums, product catalogs, or website galleries. Each resized image downloads individually.
What happens to aspect ratio?
By default, aspect ratio is locked. If you specify width, height is calculated automatically (and vice versa). This prevents distortion and stretching. You can unlock the aspect ratio if you need to stretch or squash images intentionally, but this is rarely recommended as it creates unnatural-looking results.
Are my images uploaded to your servers?
No. All resizing happens locally in your browser using HTML5 Canvas API. Your images never leave your device, are never uploaded, and are never seen by us or anyone else. This is completely private and works offline once the page loads.
What image formats are supported?
Input: JPG, JPEG, PNG, WebP, GIF, BMP, SVG, TIFF
Output: JPG, PNG, WebP (your choice)
Most common formats are fully supported. The tool automatically handles color profiles and transparency.
How do I maintain image quality when resizing?
Best practices:
• Always start with the highest quality source
• Downscale instead of upscale whenever possible
• Use appropriate output format (JPG for photos, PNG for graphics)
• If combining with compression, resize first, then compress
• For web, don't resize larger than display size
Can I resize images for specific social media platforms?
Yes! Check our "Common Image Dimensions Reference" section above for exact pixel requirements for Instagram, Facebook, Twitter, LinkedIn, YouTube, and more. Simply enter those exact dimensions to create perfectly-sized images for any platform.
What's the maximum image size I can resize?
There's no artificial limit — it depends only on your device's memory. Most modern computers can handle images up to 100MB and 20,000×20,000 pixels. Very large images may take a few extra seconds to process but will work fine.
Should I resize before or after compressing images?
Always resize first, then compress. Here's why: if you compress a 4000px image and then resize to 1000px, you've wasted compression effort on pixels that will be discarded. Resize to your target dimensions first, then apply compression for optimal file size with maximum quality.
Does resizing also reduce file size?
Yes, significantly! Reducing dimensions by 50% typically reduces file size by 70-75% (because you're removing 75% of the pixels). A 2000×2000px image resized to 1000×1000px goes from 4 million pixels to 1 million pixels — that's dramatic savings. For maximum optimization, resize AND compress.