Canceled or Cancelled: Which is Right?

[Dio Jin 교수]

While both ‘canceled’ and ‘cancelled’ are acceptable for the past tense of cancel, the version with one L is more common in American English, while the version with two L's is more common in British English. American English typically only doubles the consonant when the stress is on the syllable attached to the suffix, as in ‘remit’ and ‘remitting.’

British vs. American English
Now for the less simple answer.

Canceled (and canceling) is more common in the US, while cancelled (and cancelling) are more common in British English.

As explained by Lynne Murphy, American and British English have many similar habits when it comes to past and present participles:

both double the final consonant of a word when it follows a short vowel and has the stress on the syllable attached to the suffix (such as remit/remitted/remitting).

However, if the stress does not come on the syllable that attaches to the suffix then the final consonant is not doubled (as is the case with edit/edited/editing).