All data items are held in the native byte order of the MSP430 processor. The plain character type is signed by default. The floating-point types float and double are implemented as 32-bit and 64-bit IEEE floating-point.
| Data Type | Size in bytes | Alignment in bytes |
| char | 1 | 1 |
| signed char | 1 | 1 |
| unsigned char | 1 | 1 |
| int | 2 | 2 |
| unsigned int | 2 | 2 |
| short | 2 | 2 |
| unsigned short | 2 | 2 |
| long | 4 | 2 |
| unsigned long | 4 | 2 |
| long long | 8 | 2 |
| unsigned long long | 8 | 2 |
| float | 4 | 2 |
| double (compiled with -msd) | 4 | 2 |
| double | 8 | 2 |
| long double | 8 | 2 |
|
type * (pointer) |
2 |
2 |
|
enum (enumeration) |
2 |
2 |