# REAL(8) or DOUBLE PRECISION Constants

A REAL(8) or DOUBLE PRECISION constant has more than twice the accuracy of a REAL(4) number, and greater range.

A REAL(8) or DOUBLE PRECISION constant occupies eight bytes of memory. The number of digits that precede the exponent is unlimited, but typically only the leftmost 15 digits are significant.

IEEE* binary64 format is used.

Note that compiler option double-size can affect DOUBLE PRECISION data.

The default KIND for DOUBLE PRECISION is affected by compiler option double-size.

## Examples

Valid REAL(8) or DOUBLE PRECISION Constants
`123456789D+5`
`123456789E+5_8`
`+2.7843D00`
`-.522D-12`
`2E200_8`
`2.3_8`
`3.4E7_8`

Invalid REAL(8) or DOUBLE PRECISION Constants
`-.25D0_2` | 2 is not a valid kind for reals.
`+2.7182812846182` | No D exponent designator is present; this is a valid single-precision constant.
`123456789.D400` | Too large for any double-precision format.
`123456789.D-400` | Too small for any double-precision format.

Parent topic: Real Data Types

## See Also

General Rules for Real Constants
double-size compiler option

Compiler Reference > Data and I/O section: Data Representation