What exactly are the boundaries between Android's Density Buckets?

Question

I want to categorize our inventory of Android development devices by screen density bucket.

I easily discovered the physical densities for each device in PPI units. This is standard information given as part of product specs.

However, given the PPI number, how can I confidently categorize each device into a density bucket? The Android documentation gives a simple number for the density buckets, along with a diagram showing approximate and overlapping ranges.

For example, consider a device that has a screen density of 370 PPI. Android's XHDPI bucket is "~320", while the XXHDPI bucket is "~420". So which bucket does 370 fall into?

I've been unable to find a precise specification of where the boundaries are between the buckets; or, if they overlap, exactly how large the overlap is. Is this subjective? Do I really need to run test software on each physical device to determine the bucket?

Answer 1

It appears that the specific density bucket a device falls into is determined by the manufacturer, and does not follow a strict formula.

I imagine that this determination takes into account effective screen density as well as the # pixels and the physical dimensions of the device, so that the "bucket" that is selected produces the best results both from an asset size and a layout perspective.