What makes a nibble invalid BCD?

BCD only assigns meaning to nibble values 0000 through 1001 (0-9). Any nibble from 1010 through 1111 (10-15) has no valid decimal digit meaning, so this tool rejects it with a clear error rather than guessing.

What input format does it expect?

One 4-bit binary group per decimal digit, separated by spaces — for example "0001 0010 0011" decodes to the decimal number 123.

How is this different from a plain binary-to-decimal conversion?

A plain binary-to-decimal conversion treats the whole bit string as one number. This tool instead treats every 4 bits as one independent decimal digit and concatenates the decoded digits — the two approaches produce different results for the same bits.

Can I decode a number with a leading zero digit?

Yes — a nibble of 0000 simply decodes to the digit 0, and it's kept in its position in the output, so "1001 0000 0101" correctly decodes to "905".

BCD to Decimal Converter - Decode Binary-Coded Decimal

Overview

Introduction

Binary-Coded Decimal data shows up in calculator chips, digital clocks, and other decimal-output hardware, where each digit is stored as its own 4-bit nibble rather than as part of one big binary number.

This tool decodes that per-digit encoding back into the plain decimal number it represents.

What Is BCD to Decimal Converter?

A decoder for Binary-Coded Decimal: it reads 4-bit nibbles, one per decimal digit, and reconstructs the full decimal number.

It's the inverse of the Decimal to BCD Converter, undoing the digit-by-digit nibble encoding.

How BCD to Decimal Converter Works

Each whitespace-separated token is validated to be exactly 4 binary digits with a value of 9 or less.

Every valid nibble is converted to its decimal digit and the digits are concatenated in their original order to form the final decimal number as a string.

When To Use BCD to Decimal Converter

Use it to make sense of raw BCD data captured from a calculator, digital display driver, or hardware datasheet.

It also works as a validator: any nibble outside 0-9 is flagged immediately as not valid BCD.

Often used alongside Decimal to BCD Converter and BCD to Octal Converter.

Features

Advantages

Explicitly rejects out-of-range nibbles (10-15) instead of silently producing a nonsensical digit.
Straightforward digit-by-digit decoding that's easy to verify manually.
Handles decimal numbers of any length, since each nibble is processed independently.

Limitations

Requires strict 4-bit, space-separated nibbles; it won't parse an unbroken bit string without help.
Only reconstructs non-negative integers — there's no support for a sign nibble or fractional digits.

Examples

A 3-digit number

Input

0001 0010 0011

Output

Nibbles decode to digits 1, 2, and 3 in order, giving 123.

A number with a zero digit

Input

1001 0000 0101

Output

Nibbles decode to digits 9, 0, and 5 in order, giving 905.

Best Practices & Notes

Best Practices

If you get an out-of-range error, double-check the flagged nibble for a mistyped bit — 1010-1111 all look like plausible binary but aren't valid BCD.
Keep nibbles separated by spaces so the digit boundaries are unambiguous.

Developer Notes

Implemented as per-nibble validation (`parseInt(nibble, 2) <= 9`) followed by string concatenation of the decoded digits — no BigInt is needed since decimal digit concatenation is just string building.

BCD to Decimal Converter Use Cases

Decoding raw BCD data from a calculator or digital-display hardware datasheet
Validating that a supposed BCD data stream contains only legal 0-9 nibbles
Completing a round trip check against the Decimal to BCD Converter

Common Mistakes

Entering a nibble like 1011, which looks like ordinary binary but has no valid meaning in BCD.
Running the nibbles together without spaces, which removes the digit boundaries the decoder needs.

Tips

Use the Decimal to BCD Converter first to generate correctly formatted sample nibbles.
The number of nibbles you enter always equals the number of digits in the decoded result.

BCD to Decimal Converter