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CalcHub Blog
March 26, 20264 min read

DPI/PPI Calculator — Screen and Print Resolution Explained

Calculate DPI for printing and PPI for screen displays. Convert between pixel dimensions and physical size. Know when your image is sharp enough for any output.

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DPI and PPI get used interchangeably in everyday conversation, but they mean different things in professional contexts. Both describe resolution, but one is about physical printing and the other is about what your screen shows. Confusing the two leads to blurry prints or wrongly-sized exports.

Sort it out with the DPI/PPI calculator on CalcHub.

DPI vs. PPI: The Actual Difference

PPI (pixels per inch) describes screen resolution — how many pixels a display packs into each inch. A 27-inch 4K monitor has around 163 PPI. A retina MacBook Pro hits 220+ PPI. Higher PPI means crisper screen imagery. DPI (dots per inch) technically refers to printers — how many ink dots per inch the printer lays down. A typical inkjet photo printer runs at 1440–2880 DPI at the hardware level.

When photographers say "I need a 300 DPI image," they usually mean the file should have 300 pixels per inch at the target print size. The printer's actual DPI is a separate spec.

How to Use the Calculator

For print: Enter your image pixel dimensions and desired print size to get the resulting DPI. Or enter dimensions and target DPI to get maximum print size. For screen: Enter your display resolution and physical screen size (diagonal) to calculate PPI. For exports: Enter a physical size and target resolution to get required pixel dimensions.

Common Resolution Benchmarks

Use CaseRecommended ResolutionNotes
Photo print (close viewing)300 PPIPortraits, books, greeting cards
Large canvas/poster150 PPIViewed at arm's length
Outdoor signage25–75 DPIViewed from meters away
Retina display220+ PPIText and icons appear sharp
Standard HD display96 PPI (Windows)Web design baseline
4K monitor (27")~163 PPIEverything looks crisp
DisplayResolutionSizePPI
iPhone 15 Pro2556×11796.1"~460 PPI
MacBook Pro 16"3456×223416.2"~254 PPI
Dell 27" 4K3840×216027"~163 PPI
1080p 24" Monitor1920×108024"~92 PPI

Why "72 DPI for Web" Is Outdated Advice

You'll still hear "72 DPI for web, 300 DPI for print." The 72 DPI figure comes from old Mac monitor standards. Modern screens have completely different PPI values. For web images, what matters is pixel dimensions alone — a 1200-pixel-wide image displays at 1200 pixels wide regardless of the DPI metadata embedded in the file. The metadata is irrelevant for screen display.

What does matter for web: file size (affects load time) and pixel dimensions (affects how large it renders in a fixed-width layout).

If I change DPI in Photoshop, does it affect quality?

Only if you resample. Changing the DPI field without resampling just changes the print metadata — same pixels, different interpretation. Resampling while changing DPI actually adds or removes pixels, affecting the file. Use "Uncheck Resample" in Photoshop's Image Size dialog when you just want to change print size interpretation without touching pixel count.

What DPI does my camera shoot at?

Camera sensors record pixel dimensions, not DPI. The DPI metadata embedded in a RAW or JPEG is often 72 or 96 by default — meaningless for print. What matters is the pixel dimensions. Divide those by your target DPI to find maximum print size.

What's the best DPI for scanning old photos?

For standard 4×6 prints you want to scan and re-print at the same size: 300–600 DPI is plenty. For enlarging a small original photo, scan at higher DPI (1200–2400) so you have more pixels to work with when printing larger.

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