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.

drop dropped dropping
fit fitted fitting
stop stopped stopping

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.

allot allotted allotting
commit committed committing
infer inferred inferring
trepan trepanned trepanning

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
light bulb