What's the real size of the launcher icon on nexus 5?

Question

As the doc mentioned,the launcher icon is 48*48dp.

So I think the launcher icon should be 144 * 144px on my nexus 5.
But I research a screenshot of my nexus 5,I find it's almost 166* 163px.
Why it's bigger than 144*144px?

Is my method of calculating the size wrong?

(p.s. an app with a 144*144px icon in the drawable-xxhdpi folder is also shows 166* 163px in the launcher.)

This is my screenshot:

Answer 1

Per the info provided by someone working at Google, Nexus 5's launcher uses the launcher icon in the next DPI bucket, i.e. on Nexus 5 it will use one DPI bucket up XXHDPI --> XXXHDPI, which makes the icon 192x192. The reason why your measurement is less than 192 is because the launcher icon graphics is not supposed to fill the whole image.