Free Number Base Converter - Binary, Octal, Decimal, Hex Conversion Online

A With whole numbers, never. But fractional values are a different story. For example, 0.1 in decimal becomes a repeating binary pattern — 0.0001100110011... that goes on forever. Our converter handles this by truncating at 12 decimal places, giving you 0.000110011001 in binary. You'll see a small "approximate" label next to repeating results so you know what's happening.

A That's because binary doesn't skip digits like decimal does once you hit 10. In decimal, you wrap to two digits after 9. Binary wraps after 1 — so 2 is "10" and 3 is "11". Your brain expects decimal's pattern, but binary is just counting on two fingers instead of ten. Try entering 0 through 10 in our tool and watch each result appear side by side. You'll spot the pattern in seconds.

A Yes, you can. Type a minus sign before any number, like -42 in decimal, and our tool shows its binary representation in two's complement form. For an 8-bit system, -42 becomes 11010110. We default to 8-bit but let you toggle up to 32 bits in the advanced panel. This is a hidden capability most base converters skip entirely.

A Our tool strips them out automatically. Paste "1,000" or "1 000" into the decimal field — you'll get 1111101000 in binary. Same for hex like "FF 00 80". The converter ignores formatting characters entirely, so you don't need to clean up data from spreadsheets, code comments, or PDF tables before using it. Just paste and go.

A Octal sticks around because Unix file permissions use three bits per group — read (4), write (2), execute (1). That maps perfectly to one octal digit per user group. Type 755 into our converter and watch it become binary 111101101. You'll see the pattern instantly: owner gets 111, group gets 101, everyone else gets 101. Try switching from octal to binary and back — each octal digit becomes exactly three binary bits. No other base does that as cleanly.

A The converter just ignores it and shows a warning badge. Type "12G4" into the hex field and you'll see the G stripped out, leaving 124. If you enter something completely nonsensical like "hello world," the result fields stay blank until the input is cleaned up. The tool also auto-detects the source base from what you paste, so pasting "0x1F" into the decimal box quietly converts it as hex. That auto-detection saves you a click when working with data from different programming languages.

A The 0x prefix is a C-style convention telling compilers "this next value is hexadecimal." Our converter doesn't need it — paste 0xFF or just FF, you'll get 255 either way. The auto-detection strips prefixes like 0x, 0b, and 0o (for binary and octal) when it recognizes them. If you're copying code snippets, you can paste the entire token untouched. One less thing to clean up before converting.

A Yes, fractions work fine. Enter 10.625 and you'll get 1010.101 in binary. That's because 0.625 equals 5/8, which maps cleanly to the binary places 1/2, 1/4, and 1/8. Compare that to 10.1, which produces the repeating 1010.000110011001... and gets flagged as approximate. If you're doing hardware or networking work, stick to fractions that are powers of two when you need an exact result.

A Just click the copy icon next to any output field to grab the result instantly. You get the exact text string without any hidden formatting bugs. Paste it straight into markdown files or code comments without touching your keyboard again.

A Your browser handles every single calculation locally through client-side JavaScript. Type confidential API keys or IP addresses here without worrying about leaks. Nothing leaves your device because the internet isn't even involved once the page loads. Try disabling your Wi-Fi connection right now and watch the converter keep working normally.