The doubling rule for spelling

“The dog is running.”

The “doubling rule” in English spelling is a guideline that dictates when to double the final consonant of a word before adding a suffix. It’s most commonly applied when adding suffixes that begin with a vowel, such as “-ing,” “-ed,” “-er,” and “-est.” Here’s a breakdown of the concept:

The core principle

• 1-1-1 Rule
  • The rule primarily applies to words that follow the “1-1-1” pattern:
    • 1 syllable: The word has only one syllable (e.g., “hop,” “run,” “sit”).  
    • 1 vowel: The word has one vowel sound (e.g., “o” in “hop,” “u” in “run,” “i” in “sit”).  
    • 1 consonant: The word ends in one consonant after the vowel (e.g., “p” in “hop,” “n” in “run,” “t” in “sit”).  
• Doubling before vowel suffixes
  • When adding a suffix that begins with a vowel to a word that fits the 1-1-1 pattern, double the final consonant.  
  • Examples
    • “hop” + “-ing” = “hopping”  
    • “run” + “-er” = “runner”
    • “sit” + “-ing” = “sitting”  

Important considerations

• Multisyllabic words
  • The doubling rule can also apply to multisyllabic words, but only if the final syllable is stressed.  
  • Example: “begin” + “-ing” = “beginning” (because the stress is on the second syllable).
  • Example: “open” + “-ing” = “opening” (because the stress is on the first syllable, so you do not double the n.)
• Consonant suffixes
  • The doubling rule does not apply when adding suffixes that begin with a consonant (e.g., “-ly,” “-ness”).  
  • Example: sad + ness = sadness.  
• Vowel sounds
  • The rule focuses on the vowel sound, not just the presence of a vowel letter.

Essentially, the doubling rule helps maintain the short vowel sound in the base word when adding a vowel suffix.