Convert an integer beyond ordinary number precision
Input and settings
Input: 9007199254740993 / From: base 10 / To: base 16
Expected result
20000000000001
Number Base Converter
Convert whole numbers exactly between bases 2 through 36, including binary and hexadecimal.
How to use
These are example steps; replace the values for your task.
- Select base 16 and enter ff.
- Choose base 10 or base 2 as the target.
Enter values
Conversion result
About this tool
Whole numbers are parsed with BigInt, avoiding the precision loss that normal JavaScript numbers can introduce for large values. Negative integers are supported.
Fractions, prefixes such as 0x, and digit separators are not accepted. Bases above ten use lowercase letters in output.
Continue this task
- Japanese Numeral Writer — Convert a decimal integer to Japanese notation rather than to another numeric base.
Try a use case and check the result
Represent large or negative integers in another base without losing integer digits.
Example buttons replace the inputs and settings above and calculate. Restore previous input steps back one example at a time. After trying multiple examples, repeat restore to return to your original input. This history is lost when the page closes.
Convert a negative hexadecimal integer to decimal
Input and settings
Input: -FF / From: base 16 / To: base 10 Do not add 0x.
Expected result
-255
How to read the result
The first example uses BigInt integer arithmetic to preserve 9007199254740993 exactly. Negative values use a leading minus sign. Input letters are case-insensitive and output letters are lowercase. Leading zeroes are normalized as part of the number.
Scope and limits
The UI offers bases 2, 8, 10, 16 and 36. Fractions, exponents, digit separators, prefixes such as 0x and two’s-complement interpretation are unsupported. Outer whitespace is trimmed; internal whitespace is invalid. Very long input depends on device processing time and memory.
Verification: existing convertBase and parseBase checks cover a large-integer round trip, -FF→-255 and rejection of invalid digits, fractions and prefixes, compared with rendered output.
Continue with the next task
Convert hexadecimal ff to decimal
With base 16 as the source, ff becomes 255 in decimal or 11111111 in binary.
Each digit updates the accumulated value as previous value × base + digit. The integer is held as a BigInt.
Valid digits depend on the source base. For example, entering 2 in base 2 produces an error.
Keep the digits of a large integer
Decimal 9007199254740993 converts to hexadecimal 20000000000001. Converting it back restores the original integer. Decimals and a 0x prefix are rejected: select base 16 and paste only the digits.
Frequently asked questions
Are large integers exact?
Yes. BigInt preserves digits beyond the normal safe-integer range.
Can it convert fractions?
No. This tool handles whole numbers only.
Can I enter a 0x prefix?
No. Enter the digits only.
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