How many bytes does it take to store a number?

The size of a number in Go depends on its type.

Data type	Size (bytes)	Value range
int	Depends on architecture (32 or 64 bits)	Depends on architecture
uint	Depends on architecture (32 or 64 bits)	Depends on architecture
int8	1	-128 to 127
uint8	1	0 to 255
int16	2	-32768 to 32767
uint16	2	0 to 65535
int32	4	-2147483648 to 2147483647
uint32	4	0 to 4294967295
int64	8	-9223372036854775808 to 9223372036854775807
uint64	8	0 to 18446744073709551615
float32	4	About ±3.4e38
float64	8	About ±1.8e308
complex64	8	Two float32 values (real and imaginary parts)
complex128	16	Two float64 values (real and imaginary parts)
byte	1	Alias for uint8
rune	4	Alias for int32 (Unicode code point)

Example of determining the size of a type on a specific platform:

import (
	"fmt"
	"unsafe"
)

func main() {
	// Size of int and uint depends on processor architecture
	fmt.Printf("Size of int: %d bytes\n", unsafe.Sizeof(int(0)))
	fmt.Printf("Size of uint: %d bytes\n", unsafe.Sizeof(uint(0)))

	// Sizes of fixed types are constant
	fmt.Printf("Size of int8: %d bytes\n", unsafe.Sizeof(int8(0)))
	fmt.Printf("Size of float64: %d bytes\n", unsafe.Sizeof(float64(0)))
}