Where consonants are doubled for monosyllabic words (basically, after a short vowel and immediately before a suffix beginning with a vowel such as –ing, -er, -est or -ed), British and American English spelling is the same.
| flat | flattest |
| stop | stoppable |
| shop | shopping |
For words of more than one syllable, however, differences between British and American usage can be complicated; our guidelines on this are therefore an attempt to simplify the question by limiting comments to the doubling of the letter l and the doubling of other consonants.