Spelling: Double consonants

If a root word ends in a consonant, adding a suffix will sometimes require that you double the base word’s final consonant. How do you know when to double the consonant?

Consider the following examples, where doubled consonants are underlined.

• shipment
• shipped
• muddy
• fitful
• fittest
• waiting
• greenest

Now take a look at some larger words, whose base forms have more than one syllable.

• visitor
• occurring
• balloted
• committed

Below are the rules for doubling consonants when adding a suffix.

Rules

1. Only double the final consonant of the root word if:
   1. the base form ends in the sequence consonant-vowel-consonant (CVC) and
   2. the suffix begins with a vowel and
   3. the stress is placed on the final (or only) syllable.
2. Otherwise don’t double the consonant.

British English Note: Treat a final r as a consonant, even if you don’t pronounce it.

Let us consider some examples to see if these rules work.

Consider suffixes starting with a vowel (e.g. -ed, -ing, -er, -est, and in this case -y).

	ship		The last three letters of ship are consonant-vowel-consonant: double the final p. ship + −ed → shipped ship + −ing → shipping
	green		Green ends in vowel-vowel-consonant: don’t double the final n. green + −er → greener green + −est → greenest

Here are some more examples. Do they match the rules we just stated?

Spot the root word in each case.

• whirring
• occurring
• tighten
• lifted
• visitor
• balloted
• committed
• accountable
• famished
• friendship