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Image DPI / Print Size Calculator

Calculates print size from image pixels and PPI, or the effective PPI at a print size, with fit or crop — and reads a local image without uploading it.

100% FreeRuns in your browserBasic
How to use this calculator

How big at a given PPI

Enter the pixel size above.

What PPI at a print size

Enter the pixel size and a print size.

Print size = pixels ÷ PPI. Whether a PPI is enough depends on viewing distance and the print — this checks against the target you set, not a universal rule.

How the method works

The same pixels, two print sizes
Illustrative method
The same pixels, two print sizesA 1,800 by 2,700 pixel image printed at 300 pixels per inch is 6 by 9 inches. Tagging the same pixels 150 PPI prints them at 12 by 18 inches with each pixel twice as wide; no detail is added.At 300 PPI6 × 9 in1,800 × 2,700 pxre-tagSame pixels at 150 PPI12 × 18 inpixels twiceas largeno new detail
Print size = pixels ÷ PPI: 1,800 ÷ 300 = 6 in and 2,700 ÷ 300 = 9 in. Re-tagging the file as 150 PPI gives 12 × 18 in from the SAME 1,800 × 2,700 pixels — bigger, not sharper. Only resampling changes the pixel count, and it cannot recover detail that was never captured.

PPI is image pixels per inch; a printer's DPI counts ink dots and is a different number. Fixed example values for illustration — not your result.

How to use this calculator

  1. Enter the image's pixel width and height, or read them from a local image (it never leaves your browser).
  2. See how large it prints at a chosen PPI, or enter a print size to see the effective PPI — fitted with margins or filled and cropped.
  3. Set your target PPI to be warned when a print falls below it.

How it works

Print size = pixels ÷ PPI, and effective PPI = pixels used ÷ inches printed, along each axis.

Fit keeps the whole image and leaves margins where the shapes differ; fill covers the print and crops the overflow, so fewer pixels are used.

PPI is the image's pixel density; a printer's DPI counts ink dots — different things. Changing the PPI number stored in a file never adds detail.

A local image is read in the browser with its EXIF rotation applied; files over 30 MiB or 40 megapixels are refused rather than decoded.

Worked example

3000 × 2000 px at 300 PPI. = 10 × 6.667 in (25.4 × 16.93 cm). A 1800 × 2700 image is 6 × 9 in at 300 PPI. Spread 600 px across 10 inches and it is only 60 PPI.

Common mistakes

  • Re-tagging a file from 72 to 300 'DPI' and expecting a sharper print.
  • Confusing printer DPI with image PPI.
  • Forgetting that filling a print crops away pixels.

Tips

  • Runs in your browser. Your inputs are not saved or transmitted.

Frequently asked questions

What PPI do I need?

Often around 300 PPI for photos viewed up close, and less for large prints seen from a distance — set your own target.

Privacy?

Runs in your browser; nothing is uploaded.

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Cite this tool

Zerdly. (2026). Image DPI / Print Size Calculator. Retrieved from https://www.zerdly.com/tools/image-dpi-calculator/

Tip: Enter any known values to calculate the remaining results.

Designed to run locally in your browser. Tool inputs are not intentionally stored by Zerdly unless stated otherwise.