Protocol Buffers varint vs fixed

This article is much more a note to myself than something else but this might be interesting for people out there.

I wanted to calculate the thresholds at which it is better it is to use a fixed rather than a varint. Now, knowing that the varint are encoded in base 128, this basically means that we are dealing with power of 128. This gives us the following table:

Threshold value	Bytes size (without tag)
0	0
1	1
128	2
16,384	3
2,097,152	4
268,435,456	5
34,359,738,368	6
4,398,046,511,104	7
562,949,953,421,312	8
72,057,594,037,927,936	9

In summary:

From 268,435,456 to whatever limit you 32 bits type has, it is better to use a fixed32.
From 72,057,594,037,927,936 to whatever limit you 64 bits type has, it is better to use a fixed64.

Written on October 2, 2022