Number Base Converter

What this converter does

This Number Base Converter converts signed integers between the four most common number systems:

• Decimal (base 10)
• Binary (base 2)
• Octal (base 8)
• Hexadecimal (base 16)

It’s built for math-style integers (including very large values), not for text encoding or byte decoding.

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How to use it

1. Pick your Input base (Decimal / Binary / Octal / Hex).
2. Type or paste a number in the left box.
3. Pick your Output base.
4. Copy the converted result from the right box.

Helpful switches

• Batch by newline — convert one value per line
• Trim lines — removes extra whitespace on each line (best for pasted lists)
• Uppercase hex — outputs A–F instead of a–f

Nice detail: in batch mode, each line is processed independently, so one invalid line won’t stop the rest.

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Input rules (so you don’t get surprises)

Signed values

You can use:

• - for negative numbers (e.g. -42, -101010)
• + for explicit positive numbers (e.g. +42)

Optional prefixes

Prefixes are accepted when they match your selected input base:

• Binary: 0b1010
• Octal: 0o755
• Hex: 0xFF

Separators are ignored

Spaces and underscores are ignored, so all of these work:

• 1111_0000
• 0xFF FF
• 1 000 000

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Examples

Decimal → Binary

-42 → -101010

Hex → Decimal

0xFF → 255

Binary → Hex

10101101 → AD

Octal → Decimal

0755 (or 0o755) → 493

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Batch mode: convert lists quickly

Enable Batch by newline and paste one value per line:

Input (Binary):

1010
11110000
-1001
2

Output (Decimal):

10
240
-9
!ERROR: Binary input may contain only 0 and 1

That last row fails, but the others still convert.

Common use cases

• Converting IDs between hex and decimal
• Working with bitmasks (binary ↔ hex)
• Debugging or reading octal file permissions (octal ↔ decimal)
• Learning how number bases work
• Converting large integers safely (no floating-point rounding)

Troubleshooting

“Invalid digit for base…”

This means the input contains characters that don’t exist in the selected base:

• Binary allows only 0 and 1
• Octal allows 0–7
• Decimal allows 0–9
• Hex allows 0–9 and A–F

Fix it by either changing the input base, or removing the invalid digits.

“It converts some lines but not others”

That’s expected in batch mode: each line is handled separately so your valid rows still convert.

“My hex output is lowercase / uppercase”

Use the Uppercase hex toggle to control a–f vs A–F.

Tips

• If you frequently paste hex values, keep Uppercase hex on for a more “engineering-style” output.
• For binary readability, you can paste grouped bits like 1010_1100_1111 — separators are ignored.
• For consistent results in batch mode, enable Trim lines when pasting from spreadsheets or documents.