Change Image Dimensions in Pixels Online

Table of Contents

Change image dimensions in pixels online for free with PixoraTools. Set a custom width and height, maintain the original aspect ratio, preview your resized image, and download it in PNG, JPG, or WebP format.

Image dimensions matter when preparing pictures for websites, online forms, presentations, documents, and social media. Some platforms require specific pixel dimensions, while others recommend smaller images to help reduce upload times.

With this free online image resizer, you can adjust the width and height of an image directly in your browser. Choose your preferred dimensions, decide whether to preserve the original proportions, and export a resized copy without installing additional software.

What you can do with this free image resizer

• Change image width and height in pixels.
• Maintain the original aspect ratio automatically.
• Resize images for websites, documents, and social media.
• Preview the resized image before downloading.
• Export images as PNG, JPG, or WebP.
• Compare original and resized file sizes.
• Process images locally in your browser.

Free Online Image Resizer

Upload an image, enter the dimensions you need, and download your resized image. The tool supports images up to 20 MB and limits output dimensions to help prevent excessive browser memory usage.

＋ Choose or Drop an Image

Click below to browse your device, or drag an image into this area.

JPG, PNG, WebP and other browser-supported images · Maximum 20 MB

Choose an image to get started.

Privacy note: this tool processes the selected image locally in your browser and does not intentionally upload it to a PixoraTools processing server.

What Are Image Dimensions in Pixels?

Image dimensions describe the number of pixels across an image's width and height. For example, an image measuring 1200 × 800 pixels has a width of 1200 pixels and a height of 800 pixels.

Pixel dimensions determine how much image detail is available for display. Larger dimensions can be useful for large displays or detailed images, while smaller dimensions may be sufficient for thumbnails and compact website graphics.

Changing image dimensions creates an image with a different pixel width, pixel height, or both. The resizing process recalculates the image pixels to fit the requested dimensions.

Remember: Increasing an image's dimensions does not restore details missing from the original. Upscaling creates additional pixels through interpolation, not new original detail.

How to Change Image Dimensions Online

Step 1: Upload your image

Click Choose Image or drag and drop an image from your device. The original preview and pixel dimensions will appear in the tool.

Step 2: Enter your desired width and height

Enter the target width and height in pixels. You can type your own values or choose a preset as a starting point.

Step 3: Choose whether to maintain the aspect ratio

Keep the aspect ratio checkbox selected to preserve the original proportions. When you change one dimension, the other is calculated automatically. Turn it off if you intentionally need different proportions.

Step 4: Select an output format

Choose PNG, JPG, or WebP based on the intended use. You can adjust the quality for JPG and WebP output.

Step 5: Resize and preview

Click Resize Image to generate the resized image. Review its dimensions and file size before downloading.

Step 6: Download the result

Click Download Resized Image to save the new image to your device. Your original file remains unchanged.

Why Maintain the Aspect Ratio?

The aspect ratio is the relationship between an image's width and height. A 1200 × 800 image has a 3:2 aspect ratio. Preserving that ratio helps prevent people, objects, and other visual elements from appearing unnaturally stretched.

For example, if you resize a 1200 × 800 image to a width of 600 pixels while maintaining the ratio, its height becomes 400 pixels.

If you change the same image to 600 × 600 pixels without cropping it, the content will be squeezed or stretched. This can distort the appearance of the image.

Practical tip: If you need an image to fit a square layout without distortion, cropping it to a square first may be better than forcing a rectangular image into square dimensions.

Image Dimensions vs. File Size

Image dimensions and file size are related, but they are not the same thing.

• Image dimensions: The width and height measured in pixels.
• File size: The amount of storage space required by the image file, usually measured in KB or MB.

Reducing pixel dimensions often reduces file size because fewer pixels need to be stored. However, the final file size also depends on the image content, format, and compression settings.

A large PNG screenshot may have a different file size from a photograph with the same dimensions. Converting an image to another format can also change its file size without changing its pixel dimensions.

If your goal is to reduce file size rather than change image dimensions, an image compressor may be more suitable.

Choosing the Right Image Format

Format	Useful for	Key consideration
PNG	Screenshots, graphics, and transparent images	Lossless encoding; photographs may produce larger files.
JPG / JPEG	Photographs and everyday images	Lossy compression; does not support transparency.
WebP	Website photographs and graphics	Supports lossy and lossless compression and transparency.

Choose a format based on your needs. PNG is useful when lossless output is important, JPG is practical for many photographs, and WebP can be a good option for web delivery. When exporting transparent images to JPG, transparent areas are filled with white.

Frequently Asked Questions

Is this image resizer free?

Yes. The tool on this page has no payment step built into its code. It works in your browser and requires JavaScript to be enabled.

Can I change image dimensions to an exact pixel size?

Yes. Enter the required width and height in pixels. If aspect ratio is enabled, the tool preserves the image's original proportions, so one dimension may adjust automatically.

Will resizing reduce image quality?

Downscaling removes detail that cannot fit into the smaller output. Upscaling interpolates additional pixels but cannot restore missing detail. JPG and lossy WebP encoding may also introduce compression artifacts.

What happens if I turn off Maintain aspect ratio?

The width and height can be adjusted independently. This may stretch or squeeze the image, so review the preview carefully.

Can I resize a PNG image to JPG?

Yes. Choose JPG as the output format. Because JPG does not support transparency, transparent areas in the original image will appear white.

Does changing dimensions automatically reduce file size?

Not always. Smaller dimensions often produce smaller files, but output size also depends on image content, format, and compression settings.

Are my images uploaded to a server?

This tool processes images locally in your browser and does not intentionally send your selected image to a PixoraTools processing server.

Can I resize images on my phone?

In many modern mobile browsers, yes. Choose an image, enter the dimensions, and download the result. Very large images may be limited by your device's available memory.

Change Image Dimensions with PixoraTools

PixoraTools makes it easy to resize images to the pixel dimensions you need. Set your width and height, maintain the aspect ratio when appropriate, select an output format, and download your resized image directly in your browser.

For the best results, keep a copy of your original image and check the exported file before using it on a website, in a document, or on social media.

Note: Results depend on the original image, selected dimensions, output format, quality setting, and browser capabilities. Resizing does not guarantee a smaller file size or improve the original image's detail.