Online Binary Clock LogoOnline Binary Clock

BCD Converter

Convert decimal values into 4-bit BCD nibbles (weights 8-4-2-1). Each single decimal digit (0–9) is encoded independently into its own binary nibble.

Quick Examples:
Each digit will be converted to a 4-bit nibble
Groups of 4 bits (weights 8, 4, 2, 1)
Digit-by-Digit BCD Nibbles (8-4-2-1 Weights per Column)
BCD Decoding & Nibble Breakdown
Important BCD Rule: BCD nibbles only accept values from 0000 (0) to 1001 (9). Values 1010 (10) through 1111 (15) are invalid in standard BCD and are rejected.

Understanding Binary-Coded Decimal (BCD) Conversion

The BCD Converter is a specialized online tool for encoding decimal numbers into 4-bit Binary-Coded Decimal (8-4-2-1) nibbles and decoding BCD strings back to decimal digits. Unlike standard binary conversion which translates an entire number as a single integer, BCD converts each base-10 digit (0 through 9) individually into a 4-bit binary group.

How to Use the BCD Converter

  1. Step 1: Enter Decimal Digits: Type any non-negative decimal integer (e.g., 134509 or 2026) into the decimal input box.
  2. Step 2: Inspect 4-Bit Nibbles: Watch the tool convert each decimal digit into a separate 4-bit nibble using weights 8, 4, 2, and 1.
  3. Step 3: Toggle Diode Bits: Click individual diodes in the matrix to adjust bit states (0 or 1) per digit column.
  4. Step 4: Copy BCD Result: Click "Copy BCD String" to copy space-separated 4-bit nibbles directly to your clipboard.

Worked Example: Converting Decimal 134509 to BCD

To convert decimal 134509 (representing 13:45:09 timestamp) into BCD, split the number into six individual decimal digits and encode each digit into a 4-bit 8-4-2-1 nibble:

Digit 1: 1 → 0001 (1)
Digit 3: 3 → 0011 (2 + 1)
Digit 4: 4 → 0100 (4)
Digit 5: 5 → 0101 (4 + 1)
Digit 0: 0 → 0000 (0)
Digit 9: 9 → 1001 (8 + 1)
BCD String: 0001 0011 0100 0101 0000 1001

Reference Tables: BCD Digits 0–9 & Invalid Nibble Patterns

Decimal Digit4-Bit BCD Nibble (8-4-2-1)Weight Summation
000000 (all bits off)
100011
200102
300112 + 1 = 3
401004
501014 + 1 = 5
601104 + 2 = 6
701114 + 2 + 1 = 7
810008
910018 + 1 = 9
4-Bit PatternBinary ValueBCD Validity
101010Invalid BCD (Exceeds digit 9)
101111Invalid BCD
110012Invalid BCD
110113Invalid BCD
111014Invalid BCD
111115Invalid BCD

Common Mistakes in BCD Conversion

  • Summing Across Columns: Never add BCD nibbles together across digit columns (e.g. 0001 (1) and 0011 (3) is 13, NOT 1 + 3 = 4).
  • Using Invalid Patterns: Binary sequences 1010 (10) through 1111 (15) are invalid in BCD because BCD encodes single decimal digits (0–9) only.
  • Dropping Leading Zeros: Every BCD nibble must contain exactly four bits (e.g. digit 1 is 0001, not 1).

Want to explore more binary examples? Read our detailed guide on How Binary Clocks Work or explore worked binary clock examples.

Related Binary Time Tools & Guides

Binary Time ConverterConvert any time (HH:MM:SS) to binary or BCD with step-by-step bit math.Convert any time to binary →Binary Number ConverterConvert binary to decimal and decimal to binary instantly with a visual bit matrix.Open the binary number converter →BCD ConverterConvert decimal numbers to 4-bit BCD nibbles (8-4-2-1) and BCD back to decimal.Convert decimal to BCD nibbles →Binary Clock PracticeDrill binary-to-decimal, decimal-to-binary and full clock reading at three difficulty levels.Practice reading binary clocks →

Frequently Asked Questions

What is BCD (Binary-Coded Decimal)?

BCD (Binary-Coded Decimal) is a digital encoding method where each individual base-10 decimal digit (0 through 9) is independently converted into a 4-bit binary sequence using bit weights 8, 4, 2, and 1.

Why are bit combinations 1010 through 1111 invalid in BCD?

Four binary bits can represent 16 values (0000 to 1111). However, because BCD encodes single decimal digits (0 to 9), only the first ten combinations (0000 to 1001) are valid. Patterns 1010 (10) through 1111 (15) are invalid in standard BCD.

How is BCD different from Standard Binary?

Standard Binary converts an entire number into base 2 as a single integer (e.g., 45 becomes 101101). BCD encodes each decimal digit separately (e.g., 45 becomes 0100 for 4 and 0101 for 5).

Where is BCD used in real-world technology?

BCD is widely used in real-time clock (RTC) ICs (like the DS3231), digital pocket calculators, 7-segment LED displays, financial accounting systems, and industrial counters to eliminate decimal rounding errors.

How do I read a 4-bit BCD nibble?

Read the four bits from left to right using weights 8, 4, 2, and 1. Sum the weights of the active '1' bits to get the decimal digit value (0 to 9).

Is this BCD converter free to use?

Yes, this BCD converter is 100% free with no registration, accounts, or software installation required. All conversions run locally in your browser.