When to double the consonant before the suffix “-able”

I’m not a native English speaker and I was wondering what is the rule that decides whether to write double letter before -able.

In programming, we have abused the (English) language in new ways, needing to name attributes of objects, which are derived from verbs, e.g.:


And so on. What is the rule? Does p always repeat while the other letters do not? 🙂


If it’s a short vowel sound and a single consonant, then you double the consonant to signify that the vowel sound is supposed to stay short:

map > mappable
hit > hittable
cancel > cancellable

Otherwise (if the vowel is already long, or if there is more than one consonant already) you don’t need to double anything, because the vowel sound won’t change anyway:

junk > junkable
excite > excitable
quote > quotable

If you don’t double the consonant when you’re supposed to, it will look like the vowel is supposed to be long:

mapable = “may-puh-bull”, not “map-uh-bull”

Source : Link , Question Author : the swine , Answer Author : Hellion

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