The Ultimate Guide for Adding Suffixes in English: 7 Essential Spelling Rules for Suffixes

Adding suffixes to words in English can feel confusing at first. Sometimes letters disappear, sometimes consonants double, and sometimes spellings change in unexpected ways.

However, it’s not all unexpected or illogical… Not at all!

Below are 7 spelling rules for adding suffixes in English, explained step by step with examples.

However, first things first…

What is a Suffix?

A suffix is a letter or group of letters added to the end of a word to change its meaning. For example:

-er can mean “more,” as in bigger or taller, or a person who does something, as in runner or teacher.

-ed shows that something happened in the past, like looked or played.

Consonant VS Vowel Suffix

When learning and applying some of the rules we are going to through today, it will be essential to differentiate between vowel and consonant suffixes.

Vowel suffixes begin with a vowel letter:

• -ing
• -er
• -ed
• -y

Consonant suffixes begin with a consonant letter:

• -ly
• -ship
• -ful
• -less

This distinction is very important.

Rule 1: Final E and Suffixes

Rule: When adding a vowel suffix to a Silent Final E word, the final “e” is dropped.

So, we drop the final silent e in words like:

• make → making
• hope → hoping
• write → writing

While we keep it in words like:

• hope → hopeful
• care → careless

Special Case: Letters “C” and “G”!

If the “e” is needed, it won’t be dropped. This happens when we want to preserve the soft sound of the letters “c” or “g.”

For example:

• change → changeable
• courage → courageous

What would happen if we dropped the letter “e” in these words?
If we dropped the “e” in the base words (change/courage), the letter “G” would be pronounced /g/ (as in goat), instead of /j/ as in giraffe.

Rule 2: To Double or Not to Double the Final Consonant (CVC Rule)

Rule: When a word ends with a consonant, a vowel, and a consonant, double the final consonant, when adding a vowel suffix.

This rule applies to one-syllable words, and multisyllabic words (more than one syllable words) with stressed final syllable.

So, these are the two conditions we are looking for to double final consonant:

• The word ends in consonant–vowel–consonant (CVC)
• The suffix begins with a vowel

Examples:

run → running

hop → hopping

big → bigger

Find the rule confusing? Let’s break it down!

WORD	CONSONANT	VOWEL	CONSONANT	SUFFIX	VOWEL SUFFIX (Y/N)	WORD WITH SUFFIX
Chop	YES	YES	YES	-ing	YES	Chopping
Big	YES	YES	YES	-er	YES	Bigger
Small	NO	NO	YES	-er	YES	Smaller
Red	YES	YES	YES	-ish	YES	Reddish
Fast	NO	NO	YES	-en	YES	Fasten
Dark	NO	NO	YES	-est	YES	Tallest
Wet	YES	YES	YES	-ly	NO	Wetly
Right	YES	NO	YES	-ful	NO	Rightful
Sun	YES	YES	YES	-less	NO	Sunless
Mud	YES	YES	YES	-y	YES	Muddy

You may also want to take a look at this video, where I share step-by-step how the rule works!

By the way, video notes and practice worksheet for this rule are available here!

Important Reminder:

This rule applies to one-syllable words, and multisyllabic words with a stressed final syllable. For example:

begin → beginning

As the stressed syllable is the final one: begin.

But…

visit → visiting

Stressed syllable is the first one: visit.

Rule 3: Words Ending in Y (Change Y to I)

Rule: When the last letter of a word is “y,” and we add a suffix, the “y” is usually replaced by “i.”

For example:

• Funny (suffix: er) → funnier

• Library (suffix: -an) → librarian

This rule does not apply when:

• Adding the suffix -ing (crying),
• There’s a vowel before the letter -y (plays, boys).

Rule 4: Adding -s or -th to Words Ending in I AND Y (Add E)

This is an extension of the previous rule, really.

Rule: When the suffixes we are adding to “y” ending words are either “-s” or “-th,” we must add “e” after “i.”

For example:

• Try (suffix: -s) → tries
• Party (suffix: -s) → parties
• Fifty (suffix: -th) → fiftieth

Rule 5: FE ending Words When Adding the Plural Suffix –S

Rule: Most “fe” ending words change spelling when pluralized to “v +es.”

Examples:

• wife → wives
• knife → knives
• life → lives

IMPORTANT: While some words that only end in “f” also follow this rule (leaves, thieves, wolves), in general it only applies to words that end in “fe.”

• roof → roofs
• belief → beliefs

Rule 6: Adding –S vs -ES for Plurals

Rule: Add -es for plural suffix when the base word ends in -s, -x, z, ch, sh, ss.

When making nouns plural, the ending sound matters.

Add -es when the word ends in:

• s, x, z, ch, sh, ss
  • bus → buses
  • fox → foxes
  • dish → dishes
  • glass → glasses

For most other words, just add -s:

• cat → cats
• dog → dogs

Rule 7: The Power of Learning Suffix Spellings (Not a Rule… but Essential)

While this isn’t a spelling rule, knowing common suffix spellings makes reading and spelling much easier.

Here are 10 of the most common suffixes in English:

1. -ing (action)
2. -ed (past tense)
3. -er (more / person who does)
4. -est (most)
5. -y (having the quality of)
6. -ly (how something is done)
7. -ful (full of)
8. -less (without)
9. -ness (state or quality)
10. -ment (result or process)

Knowing the most common suffix spellings is incredibly powerful for spelling, reading fluency, and reading comprehension.

Many suffixes can sound different when spoken, but their spelling stays the same, and recognizing them as suffixes helps avoid very common mistakes.

For example, the past-tense suffix “-ed” can be pronounced three different ways — /ed/, /t/, or /d/ — but it is always spelled “ed.”

When children understand that “-ed” is a suffix that signals something happened in the past, they are much more likely to spell jumped, played, or missed correctly, even when the ending sound doesn’t clearly sound like /ed/.

Similarly, the suffix “-ful” is often confused with the word “full,” leading to misspellings like helpfull or carefull. Knowing that “-ful” is a suffix meaning “full of” and is always spelled with one “l” helps children spell words like helpful, careful, and beautiful with confidence and accuracy.

In both cases, recognizing suffixes as meaningful word parts reduces guesswork and shifts spelling from memorization to understanding.

Conclusion

Once you learn rules like the ones in this guide for adding suffixes to words, spelling stops feeling like guesswork and starts to feel more manageable and predictable.

You begin to notice the different pieces of the puzzle in each word, and move past the idea that English spelling is chaotic. On top of that, this allows youo start to develop real strategies for understanding and spelling words, instead of relying on memorization one word at a time.

Additional Resources

When picking your learn-to-spell program, look for curricula that will approach spelling in this way, instead of those that rely on rote memorization strategies.

For instance, this and this are two high-quality programs that approach spelling with strategies based on rules, and patterns, instead of memorization of endless word lists.

Of course, they are not the only ones.

In fact, if you are very hands-on and are willing to truly invest the time and do your own research, you may not even need a spelling program.

Video Explaining Rule #2 in the Guide Step-by-Step Here

Download Notes for Spelling Rule Number 2 Here

3 Simple Rules for Doubling Consonants in English Video