Number Base Converter — Bases 2–36

Choose the bases and convert one integer

1. Enter one numeral and select its source base. Use ASCII digits 0–9 and letters A–Z, with lowercase accepted. A means 10 and Z means 35; every digit must be smaller than the source base. An optional leading plus or minus is allowed.
2. Choose any target base from 2 to 36 and press Convert. The result uses uppercase letters, no redundant leading zeroes and a minus only for a negative nonzero value. Open How this conversion works for active steps or a bounded summary.
3. Copy result copies only the complete numeral, without a base label or final newline. Swap uses that result as the new input and exchanges the bases, then waits for Convert again. If the result exceeds the input digit limit, Copy remains available but Swap is disabled.

Understand the digits, value and explanation

In positional notation, each place contributes according to the selected base. The alphabet here is always 0–9 followed by A–Z. Base 20 therefore ends at J and base 26 at P; this is not the letter-only numbering used for spreadsheet columns.

No prefix or exponent is detected automatically. Characters such as B, X and E are ordinary digits whenever the selected base allows them. For example, 0x10 is invalid in base 16 but means 42804 in base 36; 1e3 means 483 in base 16, not one thousand.

The complete magnitude uses exact integer arithmetic rather than a floating-point number intermediate. For example, decimal 9007199254740993 becomes hexadecimal 20000000000001 without first rounding to a nearby number. Leading zeroes and a leading plus are representation choices, not extra precision.

For short enough values, the method reads digit values into an exact magnitude, divides by the target base and reads remainders upward, then restores the sign. Decimal, zero and same-base cases omit unnecessary operations. Longer values keep their complete exact result while detailed rows are replaced by an active summary.

Examples with signs, normalization and large integers

Use example fills -A0B in base 12 with target base 7, without calculating automatically. A is 10 and B is 11, so the magnitude is 1451. Dividing by 7 gives remainders 2, 4, 1 and 4; reading upward gives 4142 and restoring the minus gives -4142.

Converting 000ff from base 16 to base 16 gives FF: the value remains 255 while case and redundant leading zeroes are normalized. A negative zero such as -0000 becomes 0 in every target base. Significant trailing zeroes are not removed.

FF in base 16 is positive 255, while -FF is negative 255. Neither is automatically an eight-bit signed value. Decimal -18446744073709551615 converts to -FFFFFFFFFFFFFFFF; this remains a signed mathematical numeral, not a chosen-width machine word.

Explicit integer syntax and finite display limits

The received draft fits 8192 UTF-16 code units before trimming. At most 4096 magnitude digits are accepted, including leading zeroes. Only outer ASCII space, tab, CR and LF are ignored; blank or sign-only input is incomplete, not zero. Unicode digits, minus substitutions and internal whitespace are rejected.

There are no fractions, points, exponent syntax, grouping separators, arbitrary alphabets, bases outside 2–36, batch conversion, byte encodings or fixed-width and two's-complement modes. Prefix-looking characters are interpreted only as digits of the selected source base, never stripped.

The longest supported complete result has 21178 characters including a possible minus. Detailed rows are shown only up to 16 normalized source digits and 64 target digits; this affects the explanation, not exactness. A result with more than 4096 magnitude digits cannot be swapped back into this input.

These are product bounds, not a performance guarantee for every device. A browser without native exact-integer support shows an unsupported state instead of using a less accurate fallback. There is no file export, stored history or automatic conversion after an edit; an edit removes the previous answer.

Local conversion and current clipboard output

This tool adds no upload, account, saved history, input logging, persistent storage or numeral-bearing share URL. Conversion stays in the browser. Copy uses the current complete result; denial offers selection for manual copying. Existing site services remain subject to site policies; local computation does not certify them or deployment.