The integer types predefined in Free Pascal are listed in table (1.1).
| Type | Range | Size in bytes |
| Byte | 0 .. 255 | 1 |
| Shortint | -127 .. 127 | 1 |
| Integer | -32768 .. 32767 | 2 |
| Word | 0 .. 65535 | 2 |
| Longint | -2147483648 .. 2147483648 | 4 |
Cardinal | 0..4294967296 | 4 |
Free Pascal does automatic type conversion in expressions where different kinds of integer types are used.
Free Pascal supports hexadecimal format the same way as Turbo Pascal does. To specify a constant value in hexadecimal format, prepend it with a dollar sign ($). Thus, the hexadecimal $FF equals 255 decimal.
In addition to the support for hexadecimal notation, Free Pascal also supports binary notation. You can specify a binary number by preceding it with a percent sign (%). Thus, 255 can be specified in binary notation as %11111111.