Base Converter
Type a number. See it in binary, octal, decimal and hex — instantly.
Reading as Decimal. Spaces and underscores are ignored.
255 in decimal is FF in hex and 11111111 in binary. The rows update as you type.
01 Capability
What it does
Small details that make the job quicker.
- Live conversion between binary, octal, decimal and hexadecimal with no Run button.
- Uses BigInt, so 64-bit values and longer integers keep every digit instead of rounding through a float.
- Accepts a leading minus or plus, an optional matching 0b / 0o / 0x prefix, and spaces or underscores as digit separators.
- Shows the bit width and byte width, then explains the 32-bit signed and unsigned reading of the same value.
- Each row has its own copy button, plus Copy all for a labelled four-line breakdown.
- Invalid digits are named in plain language, with the digits that base actually allows.
02 Questions
Questions
Short answers, no small print.
Does it handle numbers larger than 2^53?
Yes. The conversion uses BigInt, not JavaScript numbers, so values such as 18446744073709551615 stay exact. The four rows are the real digits, not a rounded approximation. There is a 4,096-digit limit to keep the page responsive.
What do the 32-bit signed and unsigned notes mean?
The same 32 bits can be read as an unsigned value from 0 to 4,294,967,295 or as a signed value from −2,147,483,648 to 2,147,483,647. For example, 4294967295 unsigned is −1 signed. Values outside that range are still converted exactly in the four base rows; the note simply says they do not fit 32 bits.
Can I paste 0xFF or 0b1010?
Yes, when the matching base is selected. A 0x prefix is accepted in hexadecimal, 0b in binary and 0o in octal. A prefix for a different base gets a plain explanation instead of a confusing digit error.
Why did my leading zeros disappear?
Leading zeros do not change an integer's value, so the result is shown in canonical form: 00001111 becomes 1111 in binary. If you need a fixed-width field, pad the result after copying. The bit-width note tells you how many bits the value actually needs.
Does it convert fractions or negative numbers?
It converts integers only, including negative integers such as −255. A decimal point or comma is rejected with a human message because fractions and thousands separators are a different job. Spaces and underscores between digits are ignored, so 1111 1111 is read as 11111111.
Is my number sent anywhere?
No. Parsing and conversion run in this browser tab with the built-in BigInt type. There is no upload, account, logging or external request, and the value is gone when you close the page.