Image resolution calculator

Turn pixels into print size at any PPI/DPI, or print size into pixels, with megapixels and the largest good print.

By the Calcist team · Checked against known answers · Updated October 27, 2026

Private: calculated on your device. Nothing you type is sent anywhere.

Next: Resizing to a new shape? The ratio calculator keeps the proportions. Checking file sizes? Use the data storage converter.

What it does

This calculator connects an image's pixel size with its print size. Enter the pixels to see how big it prints at a given resolution, the megapixels and the aspect ratio. Or enter a print size to see how many pixels you need. A table shows the resolution your image would have at standard photo sizes, so you can see how large you can print before it gets soft.

How it's calculated

print size (inches) = pixels ÷ PPI · pixels needed = inches × PPI · megapixels = width × height ÷ 1,000,000

For centimeters, multiply inches by 2.54, since an inch is exactly 2.54 cm. When the print's shape doesn't match the image's, the image has to be cropped. Then the effective resolution is set by whichever side is shorter on pixels:

effective PPI = min(long side px ÷ long side in, short side px ÷ short side in)

Worked example

A 24-megapixel camera makes 6000 × 4000 pixel photos. At 300 PPI that prints at 6000 ÷ 300 = 20 by 4000 ÷ 300 = 13.33 inches. For an 8 × 10 print at 300 PPI you need 2400 × 3000 pixels, which is 7.2 megapixels. The 6000 × 4000 photo has plenty: on 8 × 10 paper it gives min(6000 ÷ 10, 4000 ÷ 8) = 500 PPI after cropping to the 4:5 shape.

What resolution is "good"?

300 PPI is a common target for photos viewed up close, and it's what the Library of Congress suggests when scanning everyday 4 × 6 to 8 × 10 photos. Printer drivers typically produce a finished resolution between 240 and 360 dpi. Large prints are viewed from further away, so they can use fewer pixels per inch without looking worse. The table under the result shows your image at several sizes so you can judge.

PPI vs DPI

PPI (pixels per inch) describes the image: how many of its pixels fit in an inch of print. DPI (dots per inch) strictly describes the printer: how many ink dots it lays down, often several per pixel. In practice, photo labs and software use "300 DPI" to mean 300 PPI. The DPI number stored in an image file changes nothing until you print. A 6000 × 4000 image is the same whether its file says 72 or 300.

Limitations

More pixels can't add detail that isn't there. Upscaling, a blurry shot or heavy compression won't print sharply at any PPI.
The size shown is the full image. Borders and cropping to a paper shape reduce it.
Screens don't use PPI from the file. On a screen, only the pixel dimensions matter.

Sources

How we checked this

Before every update, this calculator is run in a real browser with these known answers, and it must match all of them:

6000 × 4000 px at 300 PPI prints 20 × 13.33 in ✓
6000 × 4000 px = 24 megapixels ✓
On a 4 × 6 print that photo gives 1,000 PPI ✓
8 × 10 in at 300 PPI needs 2,400 × 3,000 px (7.2 MP) ✓
20 × 25 cm at 300 PPI needs 2,362 × 2,953 px ✓
Edge: 0 PPI is rejected ✓

Last checked October 26, 2026. Spotted something wrong? The math is done in your browser with the formula shown on this page, so you can check any result by hand.

Add this calculator to your website (free)

Paste this code into any web page. The calculator works on your page, resizes itself, has no ads and no tracking, and nothing your visitors type is sent anywhere. More about embedding.

<iframe src="https://calcist.com/embed/image-resolution-calculator/" title="Image resolution calculator" width="100%" height="640" loading="lazy" style="border:0;max-width:760px"></iframe>
<p style="font:14px/1.4 sans-serif;margin:4px 0 0"><a href="https://calcist.com/image-resolution-calculator/">Image resolution calculator</a> by Calcist</p>
<script src="https://calcist.com/embed.js" async></script>

Questions people ask

How big can I print a photo?

Divide the pixel width and height by the resolution you want. A 4000 × 3000 photo prints at 13.3 × 10 inches at 300 PPI, or 20 × 15 inches at 200 PPI.

How many pixels do I need for an 8 × 10 print?

At 300 PPI, 2400 × 3000 pixels (7.2 megapixels). At 200 PPI, 1600 × 2000 pixels.

Is DPI the same as PPI?

Not strictly. PPI is pixels per inch in the image; DPI is the printer's ink dots per inch. But most labs and apps say DPI when they mean PPI, so "300 DPI" usually means 300 pixels per inch of print.

Does changing an image to 300 DPI make it better?

No. Changing the DPI number in the file without resampling only changes the print size it suggests. The pixels, and the detail, stay the same.

Related calculators

Ratio calculatorSimplify ratios, solve proportions, split a total, convert to percent.Data storage converterGB vs GiB, TB vs TiB and bytes, and why 1 TB shows 931 GB.Unit converterLength, weight, volume, temperature, speed, data and more.Area calculatorSquare feet, meters and acres for nine shapes, with the formula.