DOUBLING CONSONANTS WITH SUFFIXES

Words of one syllable, ending with one consonant preceded by one vowel, double that consonant on adding -ed or -ing: e.g.

dropdroppeddropping
fitfittedfitting
stopstoppedstopping

Words of more than one syllable, ending with one consonant preceded by one vowel, and accented on the last syllable, double that consonant on adding -ed or -ing: e.g.

allotallottedallotting
commitcommittedcommitting
inferinferredinferring
trepantrepannedtrepanning

But words of this class not accented on the last syllable, do not double the last consonant[25] on adding -ed, -ing: e.g.

balloted, -ing
banqueted, -ing
bayoneted, -ing
benefited, -ing
biased, -ing
billeted, -ing
bishoped, -ing
blanketed, -ing
bonneted, -ing
bracketed, -ing
buffeted, -ing

carpeted, -ing
chirruped, -ing
combated, -ing
cricketing
crocheted, -ing
crotcheted, -ing, -y
discomfited, -ing
docketed, -ing
faceted, -ing
ferreted, -ing
fidgeted, -ing, -y

filleted, -ing
filliped, -ing
focused, -ing
galloped, -ing
gibbeted, -ing
gossiped, -ing, -y
initialed, -ing
junketed, -ing
marketed, -ing
packeted, -ing
paralleled, -ing
pelleted, -ing
picketed, -ing
piloted, -ing

profited, -ing
rabbeted, -ing
rabbiting
rickety
riveted, -ing
russeted, -ing, -y
scolloped, -ing
tennising
trinketed, -ing
trousered, -ing
trumpeted, -ing
velvety
visited, -ing
wainscoted, -ing

In words ending in -l, the final consonant is generally doubled, whether accented on the last syllable or not: e.g.

annulled, -ing
appalled, -ing
apparelled, -ing
barrelled
bethralled, -ing
caballed, -ing
channelled, -ing
compelled, -ing
cudgelled, -ing
dishevelled, -ing
empanelled, -ing
extolled, -ing
forestalled, -ing
grovelled, -ing

impelled, -ing
installed, -ing
kennelled, -ing
levelled, -ing
libelled, -ing
marshalled, -ing
parcelled, -ing
quarrelled, -ing
revelled, -ing
rivalled, -ing
shovelled, -ing
trammelled, -ing
travelled, -ing
tunnelled, -ing