IEEE 754 float64 hex to decimal
Useful when debugging software or reading binary files and memory values that appear in hexadecimal.
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Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Enter hex value (16 digits).
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Split the bits into S (1), E (11) and F (52). For E from 1 to 2046 the value is (-1)^S × (1 + F/2⁵²) × 2^(E-1023); E = 0 gives (-1)^S × F × 2⁻¹⁰⁷⁴; E = 2047 means Infinity or NaN.
Example
Inputs: Hex value (16 digits) = 0x400921FB54442D18. Result: Exact decimal value: 3.141592653589793115997963468544185161590576171875; Value class: Normal.
0x400921FB54442D18
3.141592653589793115997963468544185161590576171875
Limits and caveats
- Assumes big-endian order; reverse the eight bytes if you copied them from little-endian memory.
- The exact value of very small numbers can run to hundreds of digits.
Questions about this tool
What is 0x400921FB54442D18?
The double closest to π, exactly 3.141592653589793115997963468544185161590576171875.
What does shortest round-trip decimal mean?
It is what JavaScript and Python usually print, such as 0.1, because it is enough to recover the exact same bits.
What is the difference between 0 and -0?
They compare equal, but the sign bit differs, which shows in results like 1 ÷ -0 = -Infinity.