📜 Complete Guide to ASCII Binary Values for Uppercase and Lowercase Letters

In computing, ASCII (American Standard Code for Information Interchange) assigns a unique numeric code to each character, which can be represented in binary, decimal, or hexadecimal.

When using 8-bit binary, the first three bits in these letter values are usually fixed, and the last five bits change according to the letter’s position in the alphabet.

🔠 Uppercase Letters (A–Z)

In ASCII, uppercase letters start from decimal 65 (A) and go up to decimal 90 (Z). Below is the 8-bit binary ASCII table for uppercase letters:

🔡 Lowercase Letters (a–z)

Lowercase letters in ASCII start from decimal 97 (a) to decimal 122 (z).

📌 Pattern Observations

1. Uppercase Letters always start with 010 in binary (65–90).
2. Lowercase Letters always start with 011 in binary (97–122).
3. The difference between an uppercase and its lowercase letter is exactly:
   • Decimal: 32
   • Binary: The third bit from the left changes from 0 to 1.

Example:

• A = 01000001
• a = 01100001

💡 Examples of Usage

Example 1: Converting Text to ASCII Binary

Example 3: Case Conversion in Binary

• Uppercase C: 01000011 (Decimal 67)
• Lowercase c: 01100011 (Decimal 99)

Only the third bit changes, showing how binary patterns reflect letter cases.

🎯 Summary

• ASCII maps each letter to a numeric code, which can be represented in binary.
• Uppercase letters (A–Z) range from 01000001 to 01011010.
• Lowercase letters (a–z) range from 01100001 to 01111010.
• Binary is essential in data encoding, encryption, and low-level programming.