I measured using a ruler starting from middle of the knuckle to the tip of the finger -
(cm)
1: 7,0 (from the 2nd joint from the tip)
2: 9,5
3: 11,0
4: 10,0
5: 8,5
And yeah, knuckles of 4 and 5 are a bit "lower" than 2 and 3, but doesn't this only affect how close to blacks you should play, or how much you have to move towards them if needed?