# DPI vs PPI: the difference, and why 300 dpi matters [Canonical HTML page](https://gradiently.design/guide/dpi-vs-ppi) Two terms that get used as if they mean the same thing, and in conversation they mostly do. The real difference, the one sum you need, and when the number actually matters. ## The short version - PPI, pixels per inch, describes how many pixels of a digital image or screen fit into one inch. - DPI, dots per inch, describes how many dots of ink a printer places in one inch. - When a printer asks for a 300 dpi file, they mean an image with enough pixels to give 300 pixels per inch at the printed size. - To work out the pixels you need, multiply the print size in inches by 300; a 6 × 4 inch print needs 1800 × 1200 pixels. - Changing an image's dpi setting without changing its pixel dimensions does not make it sharper; only more pixels do. The short answer to **dpi vs ppi**: PPI (pixels per inch) describes a digital image or a screen, and DPI (dots per inch) describes how finely a printer lays down ink. In everyday use they are treated as the same thing, and when a print shop asks for "300 dpi" they really mean 300 pixels per inch at the finished size. What matters is the pixel count: multiply the print size in inches by 300 and you have the pixels you need. ## What PPI and DPI actually measure ### PPI: pixels per inch - Belongs to a digital image or a screen - Each pixel is one square of one colour - Decides how large an image prints sharply - A label in the file; the pixels are what count - Screens: the physical density of the display ### DPI: dots per inch - Belongs to a printer - Many tiny ink dots mix to make one colour - Decides how fine the printer's output is - A setting on the printer, often 600 to 2400 - Not something you set in a design file A printer needs several ink dots to reproduce the colour of one pixel, which is why printers quote dot densities far higher than 300. So the two numbers describe different things. Because design software and print shops say "dpi" for both, it is safest to translate any request for "300 dpi" into "300 pixels for every inch of the printed piece". ## The one sum you need ```text pixels = inches x ppi print size = pixels / ppi 6 x 4 in postcard at 300 ppi -> 1800 x 1200 px A4 (8.27 x 11.69 in) at 300 -> 2480 x 3508 px 1080 x 1350 px at 300 ppi -> 3.6 x 4.5 in millimetres to inches: divide by 25.4 ``` Every print resolution question comes down to these two lines. Run the sum backwards and you learn how large an existing image can print. A 1080 × 1350 Instagram post at 300 ppi prints sharply at only 3.6 × 4.5 inches. Stretch it to A4 and each pixel is stretched to more than twice its width, which is when prints look soft. Our guide to [resolution for printing](https://gradiently.design/guide/image-resolution-for-print) has a full table of sizes. - 1800×1200 at 300 ppi: 6 × 4 in: 6 × 4 - 1800×1200 at 150 ppi: 12 × 8 in: 12 × 8 - 1800×1200 at 72 ppi: 25 × 16.7 in: 25 × 17 One image, three print sizes, drawn to scale. The pixels never change; only how widely they are spread does, and the larger prints look correspondingly softer up close. ## Why 300 dpi for print and 72 dpi is a myth 300 pixels per inch is the long standing print standard because, at normal reading distance, people can't make out individual pixels beyond roughly that density. Posters and banners seen from further away can use less, often 150, which is covered in [poster sizes](https://gradiently.design/guide/poster-size-guide). The idea that web images should be "72 dpi" comes from early Mac screens, which happened to show 72 pixels per inch. Screens ignore the dpi label entirely; a browser or phone shows an image by its pixel dimensions. A 1200 × 630 image labelled 72 dpi and the same image labelled 300 dpi look identical on screen and are exactly the same file size, give or take a few bytes of metadata. | Situation | Resolution to aim for | What actually matters | | --- | --- | --- | | Flyers, cards, invitations | 300 ppi at print size | Pixels = inches × 300 | | Posters seen from a few metres | 150 to 300 ppi | Ask your printer | | Social posts | Any label | The platform's pixel size, such as 1080 × 1350 | | Websites | Any label | Pixel size, often twice the display size | | Logos and type for print | Vector (SVG or PDF) | No pixels at all, so no limit | Only print cares about pixels per inch. Everywhere else, think in pixel dimensions. Resolution is not the only thing that changes between a screen and paper. Colour shifts too, because screens mix light and presses mix ink; [RGB vs CMYK](https://gradiently.design/guide/rgb-vs-cmyk) explains what to expect, and [printing gradients](https://gradiently.design/guide/print-gradients) covers the smooth blends that suffer most. ## Changing dpi does not add detail Most image editors let you type a new dpi value. If you change the number without resampling, the pixels stay the same and only the suggested print size changes. If you resample upwards, the software invents new pixels by blending neighbours, which makes the image bigger but not sharper. The only real fix for a low resolution image is a larger original or a design that can be rendered again at the size you need. > **Check a file in five seconds** Ignore the dpi field. Look at the pixel dimensions, divide the width by 300, and you have the widest sharp print in inches. ## Pixel density on screens Screens have a real ppi: modern phones pack far more pixels into an inch than an old desktop monitor. To keep things readable, they draw each CSS pixel with two or three physical pixels. That is why a sharp web image is usually exported at twice the size it is displayed. The browser picks the right one if you offer it: ```html Spring collection hero ``` A 1200 × 600 banner with a double density version for high resolution screens. See MDN's guide to [responsive images](https://developer.mozilla.org/en-US/docs/Web/HTML/Guides/Responsive_images). Gradients and rendered designs dodge most of this. Because they have no fixed pixels, they can be drawn again at whatever size a screen or printer needs. Gradiently's print sizes are set at 300 dpi already, custom sizes go up to 8,000 pixels, and Pro exports up to 4K as well as SVG and print PDF. For choosing formats, see [PNG vs JPG](https://gradiently.design/guide/png-vs-jpeg) and [SVG vs PNG](https://gradiently.design/guide/svg-vs-png). ## FAQ ### What is the difference between DPI and PPI? PPI is pixels per inch in a digital image or screen. DPI is the number of ink dots a printer places per inch. In print requests, "300 dpi" means 300 pixels per inch at the finished size. ### Is 72 dpi or 300 dpi better? For print, an image needs 300 pixels per inch at its printed size. For screens the label makes no difference; only the pixel dimensions matter. ### How many pixels is 300 dpi? It depends on the size: multiply inches by 300. A 6 × 4 inch print needs 1800 × 1200 pixels, an A4 page 2480 × 3508. ### Does changing dpi improve image quality? No. Changing the dpi value only changes the suggested print size. Upscaling adds pixels but not real detail. ### What dpi should I use for Instagram? The dpi setting is ignored. Export at Instagram's pixel size, such as 1080 × 1350 for a portrait post.