Online Tool Store
IEEE 754 Float Inspector
Enter a decimal number or raw bit pattern and see its IEEE 754 single- or double-precision breakdown - sign, exponent, and mantissa bits - with the reconstructed value.
🔒 This tool runs entirely in your browser. Your files are never uploaded to a server.
Bit layout
Sign
Exponent (biased / unbiased)
Mantissa (hex)
Reconstructed value
How it works
- Enter a decimal number and choose single (32-bit) or double (64-bit) precision.
- The value is written into a typed array buffer to get its exact IEEE 754 bit pattern.
- The bit layout is colored by field: sign, exponent, and mantissa.
- Read off the biased and unbiased exponent, and the mantissa in hex and binary.
FAQ
What is IEEE 754?
It is the standard nearly all modern computers use to represent floating-point numbers in binary, splitting the value into a sign bit, an exponent, and a mantissa (fraction). JavaScript numbers, and most languages' "double" type, use the 64-bit version.
Why is 0.1 + 0.2 not exactly 0.3 in code?
Most decimal fractions cannot be represented exactly in binary floating point, so they are rounded to the nearest representable value. Inspecting the bit pattern here shows the mantissa is an approximation, not the exact decimal.
What does the exponent bias mean?
The stored exponent bits are an unsigned number offset by a bias (127 for single, 1023 for double) so the true exponent can be negative without needing a separate sign. The tool shows both the raw biased value and the unbiased exponent.
Does this run any calculation outside my browser?
No — it uses JavaScript's built-in DataView to write your number into a typed array buffer and read back the exact bit pattern, entirely client-side.
How we compare
| Feature | Online Tool Store | Manual bit-shifting in code |
|---|---|---|
| Visual, color-coded bit breakdown | ✓ | ✗ |
| Switch precision instantly | ✓ | Rewrite code |
Writing a quick script to dump bit patterns works, but this inspector shows the layout visually, in both precisions, without leaving the browser.