Number Base Converter
Exact base conversion, even for very large integers.
Runs in your browser. Nothing is uploaded — your input is processed on this device and discarded when you close the tab.
Number Base Converter
How to use this tool
- Enter a whole number and tell the tool which base it is in.
- Press Convert. All four bases appear in a table.
- Read any error literally: it names the base, so a digit that does not belong in that base is easy to spot.
Worked example
With the sample (255 in decimal), the table shows binary 11111111, octal 377 and hexadecimal FF. Because the conversion uses BigInt (exact integer arithmetic), a 40-digit decimal converts exactly too — ordinary floating-point arithmetic would round it. Try binary 11111111 back the other way: it returns 255, confirming the round trip.
What this tool does not do / Limits
This tool converts whole numbers only — no fractions, no decimal points, and no negative exponents. Inputs are limited to 1,024 digits, which is generous for real use and prevents a pasted megabyte of digits from freezing the tab. Hexadecimal output uses uppercase letters (A–F); input accepts either case.
Frequently asked questions
Why use BigInt instead of normal numbers?
Normal JavaScript numbers lose exactness beyond about 15–16 decimal digits. BigInt keeps every digit exact, however large the integer.
Why is 255 equal to FF in hex?
Each hex digit holds 4 bits: F is 15, so FF is 15×16 + 15 = 255, and eight 1-bits in binary are also 255.
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