10. Advanced
10 Advanced
10.1 Memory
A good start when programming efficiently is to know how much memory different data types and operations require. It is implementation-dependent how much memory the Erlang data types and other items consume, but the following table shows some figures for the erts-5.2 system in R9B. There have been no significant changes in R13.
The unit of measurement is memory words. There exists both a 32-bit and a 64-bit implementation. A word is therefore 4 bytes or 8 bytes, respectively.
| Data Type | Memory Size |
| Small integer | 1 word. On 32-bit architectures: -134217729 < i < 134217728 (28 bits). On 64-bit architectures: -576460752303423489 < i < 576460752303423488 (60 bits). |
| Large integer | 3..N words. |
| Atom | 1 word. An atom ref  |