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Image Resizer

Resize images to exact pixel dimensions or by percentage.

Drag & drop files here

or use the button below · processed locally on your device

Output settings

Free file tool

Free Image Resizer online

Resize images to exact pixel dimensions or by percentage. Use the tool directly in your browser with no sign-up. It supports multiple source files in the same session, so it also works as a free batch tool when you have more than one file.

Free to use

No payment required for this tool.

Batch conversion

Queue multiple source files in one session.

Browser-based

The conversion workflow runs from the web page on your device.

No sign-up

Start the file workflow without creating an account.

What Image Resizer is useful for

  • Preparing images to exact dimensions
  • Correcting orientation or framing
  • Creating a new edited copy while keeping the source

Input and output checks

Accepted input: Text or settings entered on the page.

  • Open the downloaded output before deleting or replacing the source file.
  • Check the details that matter for your use: page count, dimensions, orientation, text, duration or metadata.
  • For batch jobs, confirm every queued file produced the expected output.
  • If quality or size matters, compare more than one settings combination before choosing the final copy.

How to use this calculator: Image Resizer

  1. 1Drag & drop your file onto the upload zone, or tap Browse Files.
  2. 2Review the detected file information — size, type, resolution or page count.
  3. 3Tune the output settings to match what you need.
  4. 4Press Convert and watch the progress bar; processing happens locally in your browser.
  5. 5Download individual results, or use Download All to get a ZIP of everything.

Worked conversion example

Example: resize a 2400 × 1600 image to 1200 px wide with aspect ratio preserved. The calculated height is 800 px because both dimensions are scaled by 0.5.

Accepted input
Text or settings entered on the page
Batch behaviour
Multiple files supported

Output settings

SettingExample/defaultEffect
Width (px, 0 = auto)1280Changes how the output is encoded or arranged; preview the result before relying on it.
Height (px, 0 = auto)0Changes how the output is encoded or arranged; preview the result before relying on it.
Keep aspect ratiotrueChanges how the output is encoded or arranged; preview the result before relying on it.
Output formatPNGChanges how the output is encoded or arranged; preview the result before relying on it.

How the browser process works

Resize images to exact pixel dimensions or by percentage. The page sends the selected file and settings to its image-resize browser engine, creates a new output and downloads it without overwriting the source.

Privacy, quality checks and limitations

  • Keep the original file until the downloaded output has been opened and checked.
  • Verify page count, orientation, dimensions, text legibility, audio/video duration and metadata relevant to your use.
  • Browser-local processing reduces routine upload exposure, but your device, browser extensions and download location still matter.
  • A converted preview is not proof of legal authenticity, archival compliance, accessibility or digital-signature validity.

Frequently asked questions

Is Image Resizer free to use?

Yes. You can use Image Resizer on OneCalcApp without paying or creating an account.

Does Image Resizer support batch files?

Yes. This tool accepts multiple source files in the same session so you can process a batch without reopening the page for every file.

Do I need to sign in?

No. The conversion workflow can be used without signing in.

What should I check after conversion?

Open the downloaded output and compare the page count, dimensions, orientation, text readability, duration or other details that matter for your file type before replacing the original.

Does the tool overwrite my original file?

No. The tool creates a new output for download, so keep your original source until you have checked the converted result.

Related converters

🖼️ PDF to JPG🖼️ PDF to PNG📕 JPG to PDF📕 PNG to PDF🎨 JPG to PNG🎨 PNG to JPG🌐 WEBP to JPG🌐 JPG to WEBP

Related Guides & Articles

Step-by-step guides for this conversion and related file formats.

PDF to JPG: Complete Guide to Converting PDF Pages into Images

Learn how to convert PDF pages to JPG images, understand image quality and resolution, reduce file size, and choose the right format for documents, websites and online uploads.

Read Article →

PDF to PNG: Complete Guide to Converting PDF Pages into High-Quality PNG Images

Learn how PDF to PNG conversion works, when PNG is better than JPG, how resolution affects image quality, and how to convert PDF pages into high-quality PNG images.

Read Article →

Client-Side File Conversion with WebAssembly

How modern browsers can convert images, PDFs, audio and video without ever uploading your files to a server.

Read Article →

Physical photo size guide

Resize an image in cm, mm or inches using DPI

The Image Resizer works with pixel width and height. When an application form, passport-photo specification or print job gives a physical size in centimetres, millimetres or inches, first convert that physical size to pixels using the required DPI, then enter those pixel dimensions in the resizer above.

Centimetres to pixels

pixels = cm ÷ 2.54 × DPI

Millimetres to pixels

pixels = mm ÷ 25.4 × DPI

Inches to pixels

pixels = inches × DPI

3.5 × 4.5 cm photo size in pixels

A 3.5 × 4.5 cm photo is the same physical size as 35 × 45 mm. The pixel dimensions depend on the requested DPI, so always follow the exact portal or document specification instead of assuming one universal pixel size.

Physical sizeDPIApprox. pixelsTypical use
3.5 × 4.5 cm / 35 × 45 mm300 DPI413 × 531 pxHigh-resolution document photo
3.5 × 4.5 cm / 35 × 45 mm200 DPI276 × 354 pxLower-resolution upload
2 × 2 inch300 DPI600 × 600 pxSquare photo specification

How to resize a photo for an Indian online form

  1. 1.Read the form requirement carefully: physical size, pixel size, DPI and maximum KB are separate limits.
  2. 2.If the form gives cm, mm or inches, convert the width and height to pixels with the DPI formula above.
  3. 3.Enter the calculated pixel width and height in the Image Resizer and keep the aspect ratio when the specification allows it.
  4. 4.If a file-size limit is also specified, resize first and then compress the image to the required KB range.
Passport Size Photo MakerImage Compressor

Image resize in cm / mm / inch FAQ

Can I enter 3.5 cm × 4.5 cm directly in the Image Resizer?

The current Image Resizer uses pixels. Convert 3.5 cm × 4.5 cm to pixels using the DPI required by the application, then enter those pixel dimensions.

What is 35 mm × 45 mm at 300 DPI?

35 mm × 45 mm is approximately 413 × 531 pixels at 300 DPI after rounding to whole pixels.

Does changing pixels automatically make the file smaller in KB?

Usually reducing pixel dimensions lowers file size, but JPEG quality, image detail and format also matter. Use the Image Compressor when the portal specifies a strict KB limit.