The \u201cdoubling up\u201d rule (or the \u201c1:1:1 rule\u201d) is one of the few rules in English spelling that is correct most of the time. Given how confusing English can be, we find this reliability oddly comforting. Let\u2019s look at how it works.\n\nWhat Is the Doubling Up Rule?\nThe doubling up rule states that, when adding a vowel suffix (e.g., \u201c-ing\u201d or \u201c-ed\u201d) to a single-syllable word that ends with one vowel followed by one consonant, we should double the final consonant. For instance, \u201cdig\u201d gains an extra \u201cg\u201d when changed to \u201cdigging.\u201d Additional examples include:\n\n\n\n\n\nBase Word (Single Consonant)\n\n\nWith Vowel Suffix (Double Consonant)\n\n\n\n\nStar\n\n\nStarring, Starred, Starry\n\n\n\n\nRun\n\n\nRunning, Runner\n\n\n\n\nBig\n\n\nBiggest, Bigger\n\n\n\n\nAs you can see with \u201cstarry\u201d (i.e., lit by stars), \u201cy\u201d is sometimes treated as a vowel for this rule. Other words like this include \u201csunny,\u201d \u201cblurry,\u201d and \u201cfurry.\u201d\n\nThe Exceptions\nThe only universal spelling rule in English is that there\u2019s actually no universal spelling rule in English. As such, we need to mention a few exceptions: words that end in \u201cw,\u201d \u201cx\u201d or \u201cy.\u201d These letters aren\u2019t usually doubled in English, so single-syllable words that end in a vowel plus \u201cw,\u201d \u201cx\u201d or \u201cy\u201d don\u2019t require doubling the final letter when adding a vowel suffix:\n\n\n\n\n\nBase Word (Single Consonant)\n\n\nWith Vowel Suffix (Double Consonant)\n\n\n\n\nPlay\n\n\nPlaying, Player, Played\n\n\n\n\nSnow\n\n\nSnowing, Snowiest, Snowed\n\n\n\n\nBox\n\n\nBoxing, Boxer, Boxed\n\n\n\n\nMulti-Syllable Words\nThings get trickier with words more than one syllable long. Some still require doubling the final consonant when adding a vowel suffix, such as:\n\n\n\n\n\nBase Word (Single Consonant)\n\n\nWith Vowel Suffix (Double Consonant)\n\n\n\n\nBegin\n\n\nBeginning, Beginner\n\n\n\n\nRegret\n\n\nRegretting, Regretted\n\n\n\n\nControl\n\n\nControlling, Controlled, Controller\n\n\n\n\nThese are generally words where the final syllable is stressed.\nWhen the final syllable of a multi-syllable word is not stressed, however, the final consonant is not usually doubled. Examples include:\n\n\n\n\n\nBase Word (Single Consonant)\n\n\nWith Vowel Suffix (Single Consonant)\n\n\n\n\nOpen\n\n\nOpening, Opened\n\n\n\n\nListen\n\n\nListening, Listened, Listener\n\n\n\n\nHappen\n\n\nHappening, Happened\n\n\n\n\nIn some cases, whether to double the final consonant depends on the suffix added. \u201cPrefer,\u201d for example, gains an extra \u201cr\u201d in \u201cpreferred\u201d or \u201cpreferring.\u201d This is because, in both, the final syllable is stressed. However, no doubling is required in \u201cpreference,\u201d since the final syllable here is unstressed.\n\nMulti-Syllable Exceptions\nThere are some words that don't follow the pattern above, but with which we still double the final letter when adding a vowel suffix to clarify the pronunciation.\nWith "format," for example, we typically place the stress on the first syllable. But we still double the "t" when adding a suffix to show that it is pronounced with a short vowel sound. Thus, we pronounce "formatted" as "for-mat-ed," not "for-mate-ed," and the double "t" before the suffix helps to clarify this.\nThere are also some words that end in an \u201c-l\u201d that are conventionally spelled with a single consonant in American English, but that take a double consonant in British or Canadian English. For example:\n\n\n\n\n\nBase Word\n\n\nAmerican English (Single Consonant)\n\n\nBritish\/Canadian English (Double Consonant)\n\n\n\n\nTravel\n\n\nTraveled, Traveling, Traveler\n\n\nTravelled, Travelling, Traveller\n\n\n\n\nCancel\n\n\nCanceled, Canceling\n\n\nCancelled, Cancelling\n\n\n\n\nModel\n\n\nModeled, Modeling, Modeler\n\n\nModelled, Modelling, Modeller\n\n\n\n\nIn other words, multi-syllable words can be tricky! Using the pronunciation to guide your spelling will usually help, but don't forget to check specific words in a dictionary if you're unsure whether to double the final consonant when adding a vowel suffix. Likewise, it\u2019s important to proofread your work carefully and double check any words that you\u2019re not 100% sure are spelled correctly.