-Able vs -Ible — Which Ending Is Correct?
Is it ‘comfortable’ or ‘comfortible’? ‘Responsible’ or ‘responsable’? The -ABLE vs -IBLE ending is one of the trickiest spelling choices in English. There’s no perfect rule, but there IS a helpful pattern that works most of the time!
Quick Guide: If the root is a complete word → usually -ABLE (comfort→comfortable). If the root is NOT a complete word → usually -IBLE (vis→visible). This works ~80% of the time. This page covers all 50 key words!
✅ -ABLE — Root IS a Complete Word
🔄 -IBLE — Root is NOT a Complete Word
🔊 Keep E Before -ABLE (CE/GE Words)
⚠️ Tricky -ABLE Words (Exceptions!)
🎯 Tricky -IBLE Words
📐 5 Spelling Rules
Root = Complete Word → Usually -ABLE
If removing -able leaves a real word: comfortable (comfort), enjoyable (enjoy), washable (wash).
Root = NOT Complete Word → Usually -IBLE
If removing -ible doesn’t leave a real word: visible (vis?), possible (poss?), terrible (terr?).
After CE/GE → Keep E + ABLE
noticeable, manageable, changeable — E stays to keep C/G soft before -able.
After Soft G/C Without E → Often -IBLE
Words with soft G/C sounds often use -ible: eligible, legible, negligible.
When In Doubt → Check the -TION/-SION Form
If the noun form uses -ATION → -ABLE (admiration→admirable). If -SION/-TION → -IBLE (permission→permissible).
🐝 Spelling Quiz
🔀 Word Scramble
Unscramble the letters
✏️ Fill in Missing Letters
Type the missing letters
❓ FAQ
Is there a rule for -able vs -ible?
The best pattern: if removing the suffix leaves a complete word (comfort, enjoy, wash), use -ABLE. If not (vis, poss, terr), use -IBLE. This works about 80% of the time.
Why keep E in ‘noticeable’?
After CE or GE, the E keeps the consonant soft. Without E, C would sound like K (notik-able) and G would sound hard (manag-able). The E preserves the soft sound.
Are there more -ABLE or -IBLE words?
There are about 900 -ABLE words and only about 200 -IBLE words in English. So when in doubt, -ABLE is statistically more likely to be correct!
What about ‘capable’ — cap IS a word!
Good catch! ‘Capable’ is an exception — ‘cap’ is a word but it uses -ABLE anyway. The pattern isn’t perfect, which is why some words just need to be memorized.
Does the -TION/-SION trick really work?
Usually! If the noun form uses -ATION: admiration→admirable. If it uses -SION or -ION: permission→permissible, destruction→destructible. It’s a useful backup check.