Does my image get uploaded to a server?

No. All processing happens entirely within your browser using the HTML5 Canvas API. Your image never leaves your device.

What image formats are supported?

JPG, PNG, WEBP, and GIF are all supported. Maximum file size is 5 MB.

What format will the resized image be?

The output is saved as JPEG. For transparent PNGs, use the quality slider at 100% and note that transparency will be filled with white.

How does the aspect ratio lock work?

When the lock is active, changing width automatically adjusts height proportionally and vice versa. Click the lock icon to toggle it.

What does the target file size option do?

It uses a binary search algorithm to automatically find the highest quality setting that produces a file at or below your target size in KB.

Is there a maximum output dimension?

The maximum width or height is 4000 pixels per side. For most use cases this is more than sufficient.

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Exact Dimensions Aspect Ratio Lock File Size Target 100% Private

Image Resizer Online

Resize images to exact dimensions in seconds — 100% private, client-side processing, no uploads.

Upload your image

PNG, JPG, WEBP, GIF · Maximum 5 MB

Click to upload or drag & drop here

PNG, JPG, WEBP, GIF · Up to 5 MB

Popular presets — upload first to use

Instagram1080×1080

Facebook1200×630

Twitter1200×675

YouTube1280×720

HD1920×1080

Mobile750×1334

How it works

Resize your image in three simple steps.

Upload your image

Click or drag and drop a JPG, PNG, WEBP, or GIF file up to 5 MB. Processing is instant and entirely in your browser.

Set your dimensions

Enter exact pixel dimensions, select a social media preset, or set a target file size. Lock the aspect ratio to resize proportionally.

Download

Preview the result, adjust quality if needed, then click Download to save your resized image instantly.

Why use PortImg Resizer?

Everything you need — nothing you don't.

Client-side only

Every operation runs in your browser tab. Your image is never transmitted anywhere — not even temporarily.

Exact pixel dimensions

Enter width and height values from 1 to 4000 pixels. The live preview updates as you type.

Aspect ratio lock

Toggle the padlock between dimensions to keep proportions fixed or resize freely to a custom ratio.

Target file size

Enter a target in KB and the tool automatically finds the best quality setting to meet it using binary search.

Quality control

Fine-tune output quality from 10% to 100% using the slider. See the estimated file size update in real time.

Social media presets

One-click presets for Instagram, Facebook, Twitter, and YouTube — always sized to current platform specifications.

5 MB

Max file size

4000

Max px per side

Uploads ever

100%

Browser-based

Popular image sizes

One-click presets for every platform and format.

Instagram

1080×1080

Square post

Facebook

1200×630

Link preview

Twitter

1200×675

Card image

YouTube

1280×720

Thumbnail

1920×1080

1080p / Full HD

Mobile

750×1334

iPhone size

Frequently asked questions

Everything you need to know before you start.

: No. Every operation — loading, resizing, and quality adjustment — runs entirely inside your browser using the HTML5 Canvas API. Your image never leaves your device.
: JPG, PNG, WEBP, and GIF are all supported as input. The output is saved as JPEG. Maximum input file size is 5 MB.
: JPEG. If you need a transparent PNG output, adjust quality to 100%. Note that any transparent areas will be filled with white when saved as JPEG.
: When the padlock icon is active (filled indigo), changing width automatically recalculates height to preserve the original proportions, and vice versa. Unlock it to set any arbitrary width and height independently.
: It automatically finds the highest JPEG quality setting that produces a file at or below your target size in KB, using a binary search algorithm across up to 15 quality levels.
: The maximum width or height is 4000 pixels per side. This covers virtually all practical use cases including print-ready images.

What is an online image resizer?

An online image resizer lets you change the pixel dimensions of a photo or graphic directly in your browser — no software to install, no account to create. Modern browser-based tools use the HTML5 Canvas API to redraw the image at a new size with bicubic-equivalent interpolation, producing clean, sharp results even when scaling down significantly.

When do you need to resize an image?

Common scenarios include preparing product photos for e-commerce platforms that enforce maximum upload dimensions, resizing headshots and profile pictures to platform specifications, reducing large camera files before emailing or sharing, creating optimised web images to improve page load times, and fitting graphics to specific social media formats such as Instagram squares, Facebook link cards, or YouTube thumbnails.

Tips for the best resize results

Always start with the highest-resolution version of your image available — you can always scale down, but scaling up degrades quality. For web use, 72 dpi at the target screen size is sufficient; for print, 300 dpi is the standard. When reducing to a very small size, lower quality settings still produce acceptable results because fewer pixels are visible. Use the target file size feature to hit common platform upload limits (e.g., 200 KB for email attachments) automatically.

Resize your image now

No sign-up, no upload, no cost. Private by design.