Does it maintain aspect ratio automatically?

Yes. With the aspect ratio lock on, changing one dimension auto-calculates the other.

Can I resize to exact pixels without ratio lock?

Yes. Turn off aspect ratio lock to set both dimensions independently.

Can I resize to percentage of original?

Yes. Switch to percent mode and enter values from 1 to 500.

What social media sizes are included?

Instagram Square (1080x1080), Story (1080x1920), Twitter Header (1500x500), Facebook Cover (820x312), LinkedIn Banner (1584x396), HD, Full HD, and 4K.

Will quality be affected?

LANCZOS resampling preserves the best possible quality. Some loss is expected for large scale-ups.

Can I upscale a small image?

Yes, but AI upscaling is not applied so large upscales may appear blurry.

Is my image stored on the server?

No. Images are processed in memory and immediately discarded.

Can I use it on mobile?

Yes. The layout is fully responsive for mobile use.

Does it preserve PNG transparency?

Yes. PNG output retains its alpha channel.

Can I set only width and let height auto-calculate?

Yes. Leave height blank with aspect ratio lock on.

What does LANCZOS mean?

LANCZOS is a high-quality image resampling algorithm that minimizes aliasing and blur.

Does resizing change the file size?

Yes. Smaller dimensions produce smaller files; larger dimensions produce larger files.

Can I resize to non-standard dimensions?

Yes. Any custom pixel value is supported.

Free Image Resizer — Resize JPG PNG WebP Online

Drop image or click to upload

Presets

Width (px)

Height (px)

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Embed this tool

Add this tool to your website or blog with a single iframe snippet.

<iframe src="https://dukotools.com/tools/image-resizer?embed=1" width="100%" height="600" frameborder="0" allow="clipboard-write" loading="lazy" title="image-resizer tool"></iframe>

About Image Resizer

Image Resizer allows precise pixel or percentage-based resizing of JPEG, PNG, WebP, GIF, and BMP images with intelligent aspect ratio preservation. Unlike simple resize tools, it automatically calculates the missing dimension when you lock aspect ratio, preventing accidental stretching. Preset buttons cover the most common social media and screen dimensions including Instagram Square, Instagram Story, Twitter Header, Facebook Cover, LinkedIn Banner, HD, Full HD, and 4K. The Pillow LANCZOS resampling algorithm ensures maximum output quality at any scale.

Key Features

Pixel and Percentage Modes
Switch between absolute pixel targets and percentage scale to match different workflow needs.
Smart Aspect Ratio Lock
Auto-calculates the other dimension when you type one value so images are never distorted.
Social Media Presets
One-click presets for Instagram, Twitter, Facebook, LinkedIn, HD, Full HD, and 4K dimensions.
LANCZOS Quality Resampling
Uses the highest-quality Pillow resampling filter for sharp downscaling and upscaling.
Format Preserved
Output format matches input format so you do not lose JPEG compression or PNG transparency.
Dimension Comparison
Shows original and output dimensions side by side after resize for easy verification.

How to Use

1
Upload your image
Select any JPEG, PNG, WebP, GIF, or BMP file up to 10 MB.
2
Enter target dimensions
Type width and height in pixels, or switch to percentage mode for scale-based resizing.
3
Use a preset if needed
Click any social media or screen preset to fill dimensions automatically.
4
Review dimension preview
Check the calculated output size with aspect ratio maintained.
5
Download resized image
Click Resize and download your output in the same format as the original.

Real-World Use Cases

Social Media Content

A content creator resizes photos to Instagram Square and Story dimensions before scheduling posts.

Website Optimization

A developer uses percent mode to scale down large photographs to 50% before embedding in a web page.

Print Preparation

A designer resizes artwork to exact pixel dimensions required by a print service.

Frequently Asked Questions

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