What device mix tells you
Device mix is the breakdown of scans by device and operating system. It tells you which phones your audience actually uses, so you can test and optimise for the devices that matter instead of the one in your pocket.Device mix is about coverage, not preference. A group that is small in scans can still be large in revenue.
How to compute device mix
Device share = scans from one device group divided by total scans, multiplied by 100.Illustrative example numbers, not real-world data: 240 of 400 scans from one operating system gives 240 / 400 x 100 = 60% for that group. If the remaining 40% come from the other major system, both deserve testing, not just the majority.
How to collect the data
Read device data from your analytics or redirect tool, and group small categories into an Other bucket so the picture stays readable.Keep the raw counts, not just the final percentage. Raw counts let you recompute the metric if you later fix the definition, and they make it possible to spot a denominator problem, such as a week where exposures were estimated instead of counted. Store the counts in one place with the date range, the placements included, and the name of the person who pulled them. That small discipline turns a spreadsheet into an audit trail.
Reading the result
Never judge device mix as a single number. Break it down by operating system, device model group, and browser. A campaign that looks average overall may be strong in one segment and weak in another, and the fix is completely different in each case. Compare the same placement against its own past, and compare different placements only when their audiences and contexts are genuinely similar. A short trend over four or more comparable periods is worth far more than a single snapshot, because it separates a real shift from weekly noise.Also check the relationship between device mix and the metrics around it. If scans rise while conversions fall, the new scanners may be less interested visitors, or the landing page may have changed. If cost rises while device mix stays flat, you are paying more for the same outcome. Metrics make sense in groups, not in isolation, and the habit of reading two or three together prevents most misreadings.