Reading a byte count as hex
A file size or offset in decimal converts to the hex a debugger or hex editor would show, making the two views line up.
Decimal to Hex
Convert a decimal number to hexadecimal in your browser, with full precision for large values.
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Use Decimal to Hex
Converts decimal number to hexadecimal in this tab, with nothing sent anywhere.
Runs entirely on your deviceThe conversion happens in this browser tab. Nothing you type is uploaded, logged or stored, which is worth knowing for anything you would not paste into a search box.
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Browse all developer and data toolsAbout Decimal to Hex
Converting a decimal number to hexadecimal is a daily task once you work near the machine, because hex is how memory addresses, colour values, permission masks and byte counts are conventionally written. The reason is that hex lines up neatly with bytes - every two digits is one byte - in a way decimal never does. Most calculators handle small numbers fine and quietly fail on large ones, because they convert through a floating-point number that loses precision once the value passes about nine quadrillion. That is not an exotic edge case: 64-bit identifiers, hashes and timestamps in nanoseconds all live above it. This tool works in arbitrary-precision integers throughout, so a value of any size converts exactly, digit for digit.
Using Decimal to Hex
- The number is read as an arbitrary-precision integer, so there is no ceiling above which precision is silently lost.
- It is converted to base sixteen by repeated division, the digits emerging from least to most significant and assembled in the correct order.
- The result uses digits 0 to 9 and letters a to f, the standard hexadecimal notation.
- Leading zeros, spaces and separators in the input are tolerated, so a value copied from anywhere works.
- Zero converts to zero, and the conversion is exact for a number of any length.
Where decimal to hex helps
Working with a large identifier
A 64-bit ID converts exactly, where a calculator routing through floating point would round the last digits.
Before you use the result
- Only whole numbers convert. Hexadecimal fractions exist but are rarely what people mean, and are not produced here.
- Negative numbers are not handled as two's-complement here; enter the magnitude, since the representation depends on the bit width intended.
- The output is lower-case hex; add a 0x prefix yourself if your context expects one.
- This is a base conversion, not a byte encoding - it converts the numeric value, not the text of the digits.
- Very large numbers produce correspondingly long hex, which is expected.
Questions about Decimal to Hex
Does it handle numbers past 2^53?
Yes. It uses arbitrary-precision integers, so a 64-bit or larger value converts exactly rather than being rounded.
Why is hex useful?
Because two hex digits equal one byte, so memory addresses, colours and masks line up with the underlying bytes in a way decimal does not.
Can it convert fractions?
No. Only whole numbers. Hexadecimal fractions are rarely what is wanted.
Should the output have 0x?
It does not add one, since conventions vary. Prepend it yourself if needed.
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