Do my images get uploaded to a server?

No. All processing happens locally in your browser using the Canvas API and Web Workers. Your images never leave your device.

What is Lanczos resampling and why does it matter?

Lanczos is a high-quality resampling algorithm that uses a sinc-based convolution kernel to minimize aliasing and ringing artifacts when scaling images. It produces sharper, more accurate results than the bilinear interpolation built into the browser's canvas API, especially when downscaling photos significantly.

How does target file size (resize to KB) work?

The tool uses a bisection algorithm: it encodes the image at different quality levels and converges on the quality setting that produces the closest file size to your target, within a 5% tolerance. For PNG (lossless), it adjusts the output dimensions instead.

Can I resize multiple images at once?

Yes. Enable Bulk Mode at the top of the tool, upload up to 50 images, and download all resized files as a single ZIP.

What image formats are supported?

Input: JPG, PNG, WebP, AVIF, GIF (first frame), BMP, HEIC/HEIF, and SVG. Output: JPG, PNG, WebP, AVIF, or keep the original format.

How do I resize an image for Instagram?

Click 'Choose a Preset' and select from Instagram Square Post (1080×1080), Portrait Post (1080×1350), Landscape Post (1080×566), Story/Reel (1080×1920), or Profile Picture (320×320).

What happens to EXIF metadata (GPS, camera info)?

By default, all EXIF data is stripped (the Canvas API discards metadata automatically), and EXIF orientation is applied to the pixel data before resizing. Enable 'Preserve EXIF metadata' to keep the original EXIF in the output file.

Will resizing a GIF keep the animation?

No. Animated GIFs are supported as input, but only the first frame is processed. The output will be a static image.

Image Resizer

Resize images to exact pixels, a percentage, or a target file size — 40+ social media presets, Lanczos resampling, and bulk mode. 100% in your browser.

lockYour images never leave your browser — 100% private, no uploads.

Mode:

Safari detected — using bilinear resampling

add_photo_alternate

Drop an image here, or click to browse

Also paste from clipboard (Ctrl+V / ⌘V)

JPGPNGWebPAVIFGIFBMPHEICSVG

Why use our online Image Resizer?

Browser-based resizing uses the Canvas API and Web Workers so your images never leave your device. Supports three resize modes, 40+ social media presets, Lanczos resampling, and batch processing of up to 50 images.

How to use Image Resizer

1
Upload your image
Drag and drop an image onto the upload zone, click to browse, paste from clipboard (Ctrl+V), or import from a URL.
2
Choose a resize mode or preset
Select Dimensions, Percentage, or Target File Size. Or click 'Choose a Preset' to instantly apply dimensions for Instagram, YouTube, passport photos, and more.
3
Adjust settings
Set width and height, lock the aspect ratio, choose a resampling algorithm, and select your output format and quality.
4
Download your resized image
Click Download to save the resized image. For bulk mode, download all as a ZIP file.

Resize vs compress — what's the difference?

Resizing changes the pixel dimensions of an image. Compressing reduces the amount of data used to represent those pixels. Both reduce file size, but in different ways.

Resizing is the more powerful lever when an image is larger than it needs to be. A 4000×3000 photo displayed at 800×600 contains 25× more pixels than necessary — resizing it eliminates that data entirely before any encoding happens.

Compression then reduces the encoded size of the resized image. Lossy formats like JPEG and WebP discard high-frequency detail that the eye is least sensitive to. PNG is lossless — re-encoding a PNG as PNG cannot reduce its file size beyond what the original encoder achieved.

For the best results: resize first to match your display dimensions, then compress. Google Lighthouse and Core Web Vitals flag oversized images as one of the highest-impact performance improvements on most websites.

Choosing the right resampling algorithm

When you scale an image, the resampling algorithm determines how new pixel values are computed from the original pixels.

Nearest Neighbor assigns each output pixel the value of the closest input pixel. It's the fastest algorithm and produces hard edges — ideal for pixel art and sprite scaling, but creates visible jaggies on photographs.

Bilinear interpolation linearly blends the four nearest input pixels. It's fast, smooth, and built into every browser's canvas drawImage() call. Acceptable for moderate scaling but can look slightly blurry on aggressive downscales.

Bicubic interpolation uses a 4×4 neighborhood of pixels and a cubic polynomial kernel. It preserves edges better than bilinear and is the default in Photoshop. Good balance of quality and speed.

Lanczos (a=3) uses a sinc-based kernel evaluated over a 6×6 pixel window. It minimizes aliasing and ringing artifacts and produces the sharpest results for downscaling photographs. It's slower than the other algorithms — implemented here with a two-pass separable convolution in a Web Worker to keep the UI responsive.

Frequently Asked Questions

Do my images get uploaded to a server?: No. All processing happens locally in your browser using the Canvas API and Web Workers. Your images never leave your device.
What is Lanczos resampling and why does it matter?: Lanczos is a high-quality resampling algorithm that uses a sinc-based convolution kernel to minimize aliasing and ringing artifacts when scaling images. It produces sharper, more accurate results than the bilinear interpolation built into the browser's canvas API, especially when downscaling photos significantly.
How does target file size (resize to KB) work?: The tool uses a bisection algorithm: it encodes the image at different quality levels and converges on the quality setting that produces the closest file size to your target, within a 5% tolerance. For PNG (lossless), it adjusts the output dimensions instead.
Can I resize multiple images at once?: Yes. Enable Bulk Mode at the top of the tool, upload up to 50 images, and download all resized files as a single ZIP.
What image formats are supported?: Input: JPG, PNG, WebP, AVIF, GIF (first frame), BMP, HEIC/HEIF, and SVG. Output: JPG, PNG, WebP, AVIF, or keep the original format.
How do I resize an image for Instagram?: Click 'Choose a Preset' and select from Instagram Square Post (1080×1080), Portrait Post (1080×1350), Landscape Post (1080×566), Story/Reel (1080×1920), or Profile Picture (320×320).
What happens to EXIF metadata (GPS, camera info)?: By default, all EXIF data is stripped (the Canvas API discards metadata automatically), and EXIF orientation is applied to the pixel data before resizing. Enable 'Preserve EXIF metadata' to keep the original EXIF in the output file.
Will resizing a GIF keep the animation?: No. Animated GIFs are supported as input, but only the first frame is processed. The output will be a static image.