DPI vs PPI: Understanding Resolution Standards
DPI (dots per inch) and PPI (pixels per inch) are often confused, but they serve different purposes in campaign artwork production. Understanding the distinction is critical when preparing assets for different media channels.
What is DPI?
DPI measures the number of ink dots a printer applies per inch of paper. It's the standard for print media – billboards, leaflets, magazine adverts, and packaging. Most UK print jobs require a minimum of 300 DPI for high-quality output. Lower DPI values (72–150) result in visible pixelation and poor colour reproduction on printed materials.
What is PPI?
PPI measures the number of pixels per inch on a digital display – screens, tablets, smartphones, and websites. It determines how sharp and detailed images appear on devices. Modern displays typically range from 72 PPI (older monitors) to 326+ PPI (smartphone retina displays). For digital campaigns, PPI matters less than overall pixel dimensions; a 1920×1080 image scales appropriately across devices.
Why It Matters for Campaign Work
Using the wrong resolution wastes budget and damages brand reputation. A billboard artwork saved at 72 DPI will appear blurry when printed at large scale. Conversely, exporting social media graphics at 300 DPI creates unnecessarily large files, slowing load times without visible quality improvement.
When to Use Each
Print campaigns require 300 DPI: - Outdoor advertising (posters, billboards) - Direct mail and brochures - Point-of-sale materials - Packaging and labels
Digital campaigns typically use 72–96 PPI: - Website banners and graphics - Social media posts - Email newsletters - Digital display ads
UK Media Context
UK print suppliers and outdoor advertising networks (like those managing Transport for London campaigns) have strict technical specifications. Non-compliance often results in rejected files or production delays. Always confirm DPI requirements with your print vendor before finalising artwork.
Common Mistakes
- Upscaling low-resolution images for print
- Saving print files as web-quality JPEGs
- Assuming PPI and DPI are interchangeable
- Not accounting for colour space (RGB vs CMYK) when converting between formats
At Connect Media Group, we ensure all campaign artwork meets channel-specific requirements, optimising both file size and output quality.