IEEE 754 float32 hex to decimal
Useful for reading floats from a memory dump, a data packet or a binary file, such as sensor readings over Modbus.
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How to use it
- Enter hex value (8 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 (8) and F (23). For E from 1 to 254 the value is (-1)^S × (1 + F/2²³) × 2^(E-127); E = 0 gives (-1)^S × F × 2⁻¹⁴⁹; E = 255 means Infinity or NaN.
Example
Inputs: Hex value (8 digits) = 0x40490FDB. Result: Exact decimal value: 3.1415927410125732421875; Value class: Normal.
0x40490FDB
3.1415927410125732421875
Limits and caveats
- Assumes the usual big-endian writing order; reverse the bytes if you copied them from little-endian memory.
- All NaN patterns show as NaN without the payload detail.
Questions about this tool
What is 0x40490FDB?
Exactly 3.1415927410125732421875, the float32 closest to π, usually written 3.1415927.
What is the difference between the exact value and the shortest decimal?
The exact value is what memory holds. The shortest decimal is the briefest number that converts back to the same bits.
My bytes read CDCC4C3E. How do I decode them?
That is little-endian order. Reverse the bytes to 3E4CCCCD and enter that.