# Number of Bytes > Size (in bytes) of a [double-precision floating-point number][ieee754].

## Usage ```javascript var FLOAT64_NUM_BYTES = require( '@stdlib/constants/float64/num-bytes' ); ``` #### FLOAT64_NUM_BYTES Size (in bytes) of a [double-precision floating-point number][ieee754]. ```javascript var bool = ( FLOAT64_NUM_BYTES === 8 ); // returns true ```

## Examples ```javascript var FLOAT64_NUM_BYTES = require( '@stdlib/constants/float64/num-bytes' ); console.log( FLOAT64_NUM_BYTES ); // => 8 ```

[ieee754]: https://en.wikipedia.org/wiki/IEEE_754-1985