How many bits does "Nat" take?

[Nakamotik]

Is it dynamic or fixed size?
If it is dynamic, for small numbers(0-100) Nat will be more memory efficient than Nat64?

[skilesare]

Dynamic. I think if you need to just use small numbers that a nat8 would Use less logic, but but I’ll let a compiler person answer.

[jzxchiang]

This is my goto resource on this topic:

Is there any document about the amount of memory occupied by the basic types of Motoko canister?

Nat32, Char: 8 bytes Int64: 12 bytes Nat and Int: “free” if smaller than 2^30, else at least 20 bytes, up to arbitrary sizes Text and Blob: up to 8+n+3 bytes. opt: “free” unless you deal with the value ?…?null List is not a basic type. Probably 12*n Free means that it’s stored inside the containing data structure without extra allocation.