| double | | float64 |
| float | | float32 |
| int32 | Uses variable-length encoding. Inefficient for encoding negative numbers – if your field is likely to have negative values, use sint32 instead. | int32 |
| int64 | Uses variable-length encoding. Inefficient for encoding negative numbers – if your field is likely to have negative values, use sint64 instead. | int64 |
| uint32 | Uses variable-length encoding. | uint32 |
| uint64 | Uses variable-length encoding. | uint64 |
| sint32 | Uses variable-length encoding. Signed int value. These more efficiently encode negative numbers than regular int32s. | int32 |
| sint64 | Uses variable-length encoding. Signed int value. These more efficiently encode negative numbers than regular int64s. | int64 |
| fixed32 | Always four bytes. More efficient than uint32 if values are often greater than 2^28. | uint32 |
| fixed64 | Always eight bytes. More efficient than uint64 if values are often greater than 2^56. | uint64 |
| sfixed32 | Always four bytes. | int32 |
| sfixed64 | Always eight bytes. | int64 |
| bool | | bool |
| string | A string must always contain UTF-8 encoded or 7-bit ASCII text. | string |
| bytes | May contain any arbitrary sequence of bytes. | []byte |