PPI / DPI Calculator

What PPI and DPI actually measure

PPI (pixels per inch) describes how densely packed the pixels are on a screen — the same 1920×1080 resolution looks noticeably sharper on a 14-inch laptop than on a 27-inch monitor, because the exact same number of pixels is spread across a much smaller or larger physical area. DPI (dots per inch) is the equivalent idea for printing, describing how many ink dots a printer lays down per inch. This calculator handles both directions: find a screen's PPI from its resolution and size, or work backward from a target print DPI to the pixel dimensions an image actually needs.

How to use it

• Screen PPI tab: Enter a screen's horizontal and vertical resolution in pixels and its diagonal size (inches or centimeters) to get pixel density, aspect ratio, pixel pitch, and total megapixels.
• Print Size from DPI tab: Enter your target print dimensions and a DPI (300 is the standard for sharp photo prints), and get the exact pixel dimensions your source image needs to be to print cleanly at that size.
• Compare Two Screens tab: Enter the resolution and size for two different displays side by side to see which one actually has the sharper pixel density — useful when a bigger screen with a "higher" resolution can still have lower PPI than a smaller one.

Why a bigger resolution number doesn't always mean a sharper screen

A 40-inch 4K TV (3840×2160) has a lower PPI than a 27-inch 4K monitor with the identical resolution, because the same pixel count is stretched across a much larger physical area. This is exactly why PPI, not raw resolution, is the number that actually determines how sharp text and images look up close — and why smartphones (viewed a few inches from your eyes) need a much higher PPI to look sharp than a TV viewed from across a room.

Real-world use cases

• Shopping for a monitor or laptop: Compare pixel density across different screen sizes before buying, especially when comparing a resolution bump against a size increase.
• Preparing images for print: Figure out exactly what pixel dimensions a photo needs to be to print sharp at a specific size, instead of guessing and getting a blurry result.
• Design and UI work: Understand how a design will actually render across devices with very different pixel densities, from a budget phone to a high-end Retina-class display.
• Photography and stock image sizing: Check whether a camera's megapixel count is enough to print at a target size and DPI without upscaling.

Frequently asked questions

What PPI counts as "sharp" for a screen?

Above roughly 300 PPI is generally considered indistinguishable from print quality at typical phone viewing distance (what Apple originally marketed as "Retina"), while 100-150 PPI is typical and perfectly comfortable for a desktop monitor viewed from further away.

Why does my printer need 300 DPI when my screen looks fine at 96 PPI?

Screens are viewed with backlit, anti-aliased pixels at a distance where lower density still looks smooth, while print relies on physical ink dots viewed up close with no backlighting — 300 DPI is the long-standing standard for photo-quality print sharpness that avoids visible dot patterns or "pixelation."

Is DPI the same thing as PPI?

Not technically — PPI describes pixel density on a digital display or in a digital image file, while DPI describes physical ink dots a printer produces. In casual use the terms get swapped constantly, and for most purposes (like sizing an image for print) they can be treated as equivalent.

How do I know what diagonal size to enter for my screen?

Check the manufacturer's spec sheet or product listing — screen size is always advertised as the diagonal measurement (corner to corner), not the width or height individually, which is exactly the number this calculator expects.