Input
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How to use
- Paste a hex value, optionally with a leading 0x.
- Check the decimal result and any invalid-digit message.
- Copy the decimal value or download a batch as JSON.
Interpreting hexadecimal digits numerically
Hexadecimal abbreviates binary values using digits 0–9 and A–F. Converting a value to decimal can make a mask, counter or identifier easier to compare with a decimal log entry.
A hex string is interpreted as one number. It is not decoded as text, split into color channels or rearranged into a different byte order.
Representations and workflow
Input is case-insensitive: ff, FF and 0xFF all represent 255. A matching prefix is removed before conversion, and underscores may group digits.
0xFFFFFFFFFFFFFFFF18446744073709551615The largest unsigned 64-bit value is shown without floating-point rounding.
Precision and validation
The full unsigned 64-bit value FFFFFFFFFFFFFFFF converts to 18446744073709551615. It never passes through a JavaScript Number, so the final digits remain intact.
Interpreting and reusing the result
F or a leading high bit does not imply a sign. To interpret FFFFFFFF as signed 32-bit −1, select that width in the Bitwise Calculator. This converter returns the positive magnitude unless you enter a minus sign.
Numbers: up to 500 lines / 1 MiB, at most 4,096 characters per numeral. Fraction output: 1–128 digits. Text and byte data: 64 KiB. Bitwise operations: 8–256 bits. Workers stop after 30 seconds; inputs are not uploaded.
Frequently asked questions
Are uppercase and lowercase hex equivalent?
Yes. A–F and a–f have the same values. An optional 0x or 0X prefix is accepted.
Why is FFFFFFFF positive?
No signed machine width is assumed. The mathematical value is 4294967295; signed two’s-complement interpretation is handled by the Bitwise Calculator.
Can I paste colon-separated bytes?
No. Enter one numeral, such as 0xDEADBEEF or DEAD_BEEF. Byte dumps and endianness changes belong in Hex Byte Reverser.
Is my input sent to a server?
No. Computation runs in a browser worker. DevToolsy does not upload or store your input.
What does Copy include?
Copy exports the selected displayed value. Download JSON preserves strings and diagnostic codes; it does not turn large numbers into floating-point values.