What Number Is M in the Alphabet? M = 13

M is the 13th letter of the English alphabet. It sits at the midpoint of the 26-letter alphabet, with 12 letters before it (A through L) and 13 letters after it (N through Z). M is one of the most frequently searched letters for its alphabet position, partly because of its connection to the number 13. Convert M or any letter instantly with our letters to numbers converter.

M in Every Number System

See all 26 letters with their encodings on our alphabet number chart.

M: The Middle of the Alphabet

With 26 letters in the English alphabet, the mathematical midpoint falls between positions 13 and 14. M at position 13 is the last letter of the first half, and N at position 14 begins the second half. This makes M commonly referred to as "the middle letter."

This midpoint property gives M a special role in the ROT13 cipher, one of the simplest and most well-known letter substitution ciphers. ROT13 shifts each letter 13 positions forward, which means:

• A (position 1) becomes N (position 14)
• M (position 13) becomes Z (position 26)
• N (position 14) becomes A (position 1)
• Z (position 26) becomes M (position 13)

ROT13 is its own inverse: applying it twice returns the original text. This works precisely because the alphabet has 26 letters and 13 is half of 26. Try encoding with our A1Z26 cipher tool.

The Number 13 and M

The number 13 has a rich cultural history that adds intrigue to the letter M's position:

• Triskaidekaphobia: The fear of the number 13 is so common that many buildings skip the 13th floor, going from 12 directly to 14.
• Friday the 13th: Considered unlucky in Western cultures, this superstition may trace back to the arrest of the Knights Templar on Friday, October 13, 1307.
• 13 stripes on the US flag: Representing the original 13 colonies, making 13 a foundational number in American history.
• Baker's dozen: 13 items instead of 12, a practice dating to medieval England where bakers added an extra loaf to avoid penalties for short-changing customers.

M in Codes and Symbols

• Roman numerals: M = 1000. The word "millennium" comes from the Latin "mille" (thousand).
• Morse code: M is represented as two dashes: — —
• NATO phonetic alphabet: M = "Mike"
• Metric prefix: M = Mega (10^6, or one million)
• Computing: M often abbreviates Megabyte (MB) or Megabit (Mb)

The History of the Letter M

M evolved from the Egyptian hieroglyph for water, which showed a wavy line. The Phoenicians simplified this to their letter "mem" (meaning "water"), which looked like a zigzag wave. The Greeks adopted it as "mu" and straightened the waves into the angular shape we know today. The two vertical strokes of M can still be imagined as stylized waves.

M in Programming

// JavaScript
"M".charCodeAt(0)        // 77
"M".charCodeAt(0) - 64   // 13

# Python
ord('M')                  # 77
ord('M') - 64             # 13

// Java / C#
(int) 'M'                 // 77
'M' - 'A' + 1             // 13

Quick Reference: Letters Near M