About this tool
Enter a number in any base — binary, octal, decimal or hexadecimal — and see it converted to all four simultaneously. Large values are handled with arbitrary precision, so 64-bit numbers convert without the rounding errors that plague calculator apps.
Different bases are different lenses on the same value: hex compresses every 4 bits into one digit (which is why it dominates memory addresses and color codes), octal groups 3 bits (Unix file permissions), and binary is what the hardware actually stores.
How to use it
- Pick the base of your input number.
- Type the number — invalid digits for that base are flagged.
- Read the value in all four bases and copy any of them.
Frequently asked questions
Why is hexadecimal so common in programming?
One hex digit represents exactly four bits, so a byte is always two hex digits. 255 is FF; the RGB color white is FFFFFF. It is binary in compressed, readable form.
What is the largest number I can convert?
Effectively unlimited — the converter uses arbitrary-precision integers (BigInt), so it goes far beyond 64-bit without losing accuracy.
Why does 0644 matter in Linux?
File permissions are octal: each digit packs the read/write/execute bits for owner, group and others. 644 means rw-r--r--.