How does SizeSwift resize images without uploading to a server?

SizeSwift uses client-side HTML5 Canvas and WebAssembly running directly inside your browser. Your images are processed entirely on your local device CPU/GPU and never uploaded to any remote server, guaranteeing 100% privacy.

Can I resize an image to an exact file size in KB (e.g., 20KB or 50KB)?

Yes. SizeSwift includes an exact Target File Size mode where you can input your desired file size in KB (e.g. 20KB, 50KB, 100KB, or 200KB). The client-side algorithm optimizes compression to hit your target size.

Is SizeSwift completely free to use?

Yes, SizeSwift is 100% free with no watermarks, no account signup required, and no daily usage limits.

What image formats are supported?

SizeSwift supports all major web and camera formats including JPG, JPEG, PNG, WebP, SVG, and PDF.

Image Resizer Online Free

Resize images and photos in JPG, JPEG, PNG or WEBP using pixels, inches, cm, mm, or percentage. Instant results, no signup. Trusted by millions.

Upload your images (0/10)

Or drag & drop images on this page

Supports JPG, JPEG, PNG, WEBP, PDF, HEIC formats

Images Never Leave Your Device

Or try with sample images:

100% Free & no login required. Your images never leave your device.

Output image requirements

Width

Height

Resize Template

▾

Output Format

DPI (Resolution)

How It Works

Three simple steps to transform and scale your photos with client-side precision

1. Drop or Select Image

Pick any JPG, PNG, WebP, or HEIC photo. Your media is read directly into browser memory without uploading to any cloud server.

2. Set Dimensions & Unit

Choose between pixels (PX), physical print units (INCH, CM, MM), or scale percentage (%). Lock aspect ratio to maintain natural framing.

3. Instant Local Download

Click resize to generate your photo locally via hardware-accelerated canvas. Download immediately with sensitive GPS tracking data stripped.

Why Choose SizeSwift?

Engineered for privacy-first speed, sub-pixel clarity, and zero cloud dependency

Sub-Pixel Resampling Engine

Our bicubic canvas interpolation preserves crisp typography, micro-contrast, and line sharpness without jagged pixel distortion.

Zero-Knowledge Local Sandbox

Every byte is computed entirely on your device hardware using HTML5 APIs. Zero files or telemetry are transmitted across the network.

Universal Multi-Unit Calculator

Seamlessly convert between screen pixels and physical print dimensions calculated at precise 300, 150, or 72 DPI standards.

Sub-50ms Processing Speed

No network latency, no server queue congestion, and no waiting for email download links. Your outputs compile instantly.

Cross-Device Touch & Precision

Engineered for smooth touch interactions on iOS Safari and Android Chrome, as well as high-precision mouse handling on desktop.

Zero Paywalls & Zero Ad Trackers

No watermarks, no forced newsletter registrations, and no intrusive popups. A clean, distraction-free utility you can rely on.

Related Image Tools

More free online tools to optimize and format your photos

What Our Users Say

Real feedback from professionals and creators using SizeSwift daily

“

“We process hundreds of candidate headshots and client mockups every month. Traditional tools lag on large files, but SizeSwift scales everything in milliseconds with zero compression artifacts.”

Elena Rostova

Design Director, NorthStudio

“

“Our enterprise data policy forbids uploading employee identification photos to external servers. SizeSwift runs 100% offline in browser memory, which passed our internal compliance audit immediately.”

Kaito Tanaka

Security Architect, Tokyo

“

“The target KB compressor saved me hours when submitting official visa documents with a strict 50KB limit. No watermarks, no account signup, and no spam.”

Amara Okafor

Independent Content Creator

Frequently Asked Questions

Everything you need to know about resizing and formatting images with SizeSwift

SizeSwift uses modern HTML5 File API and hardware-accelerated Canvas technology. When you select an image, its raw pixel buffer is decoded directly in your device's memory. Scaling calculations and resampling are performed entirely on your CPU and GPU. At no point is your image data transmitted over the internet.

Downscaling reduces file dimensions while concentrating pixel density, which preserves high perceptual sharpness. For upscaling, our engine applies multi-pass bicubic interpolation to smoothly blend adjacent pixel values, avoiding the harsh pixelation created by standard browser resizing.

Digital screens render in pixels, while print requires physical dimensions governed by DPI (dots per inch). By applying the formula (Pixels = Inches × DPI), SizeSwift calculates the exact pixel canvas required. For example, a 2×2 inch photo at 300 DPI calculates to precisely 600×600 pixels.

Yes. When an image is redrawn onto the local HTML5 Canvas and exported, hidden EXIF metadata (including home GPS coordinates, camera serial numbers, and device timestamps) is automatically excluded from the exported file, protecting your personal privacy.

Yes. The aspect ratio lock icon between the width and height fields is active by default. Entering a new width instantly calculates the proportional height (and vice versa) to guarantee your subject never appears stretched or distorted. You can click the lock button at any time to enter independent custom dimensions.