This may be the answer to your question:
1 In a word with 1 syllable, double the final consonant ONLY if the word ends in 1 vowel + 1 consonant.
tip: He tipped the waiter. /He isn't tipping the waiter.
cram: The students crammed for the test. /The students were cramming for the test.
regret: Carl regretted the things he had said. /Carl was regretting the things he had said.
2 In a word with 2 or more syllables, double the final consonant ONLY if the word ends in
1 vowel + 1 consonant AND the final syllable is stressed.
vote: voted, voting (vote ends in a vowel)
instruct: instructed, instructing (instruct ends in 2 consonants)
listen: listened, listening (listen has 2 syllables and the final syllable is not stressed)
3 At the end of a word, don’t count w, x, or y as a consonant.
source: