• 4-minute read
  • 21st February 2017

Spelling Tips: The Doubling Up Rule

As far as English spelling rules go, the ‘doubling up rule’ is pretty reliable. This isn’t to say there are no exceptions (there are). But you can trust it in most situations, making it quite handy if you want to avoid errors in your written work! In this blog post, we explain how and when it works.

The Doubling Up Rule

The basic version of the doubling up rule applies when adding a vowel suffix (e.g. ‘-ing’ or ‘-ed’) to a one-syllable word that ends in one vowel followed by one consonant (this is why it’s also known as the ‘1:1:1 rule’).

And when this happens, we double the final consonant.

For instance, ‘hop’ is a single-syllable word that ends in one vowel (‘o’) and one consonant (‘p’). When we add a vowel suffix, we double the final ‘p’ (e.g. ‘hopping’ or ‘hopped’). If we didn’t do this, we’d end up with a completely different word (i.e. ‘hoping’ or ‘hoped’). Other examples include:

Base Word (Single Consonant)

With Vowel Suffix (Double Consonant)


Nodding, Nodded


Flipping, Flipped, Flipper


Barring, Barred

‘Y’ is sometimes treated as a vowel, too, so we also double the final consonant when adding a ‘y’ to single syllable words that end in a vowel and a consonant (e.g. ‘star’ becomes ‘starry’ and ‘sun’ becomes ‘sunny’).

The Exceptions

There are some exceptions to the rule above: words that end in ‘w’, ‘x’ or ‘y’.

These letters are hardly ever doubled in English, so we keep the single consonant when adding a vowel suffix to words that end in one of these letters. ‘Box’, for example, becomes ‘boxed’ and ‘boxing’ (not ‘boxxed’ or ‘boxxing’). Other examples of exceptions include:

Base Word (Single Consonant)

With Vowel Suffix (Single Consonant)


Blowing, Blower, Blowy


Taxing, Taxed


Playing, Played, Player

Multi-Syllable Words

The rule for adding vowel suffixes to multi-syllable words is more complicated, since it depends on how the word is pronounced. When the final syllable in a multi-syllable word is stressed, we stick to doubling the final consonant when adding a vowel suffix:

Base Word (Single Consonant)

With Vowel Suffix (Double Consonant)


Occurring, Occurred, Occurrence


Abetting, Abetted


Propelling, Propelled, Propeller

When the final syllable of a multi-syllable word is not stressed, the final consonant is not typically doubled when adding a vowel suffix. For instance:

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Base Word (Single Consonant)

With Vowel Suffix (Single Consonant)


Happening, Happened


Listening, Listened, Listener


Visiting, Visited, Visitor

Further Complications

This rule about doubling the final consonant in multi-syllable words can be confusing when the pronunciation depends on the vowel suffix being added.

With ‘prefer’, for example, we double the ‘r’ when adding ‘-ing’ because the stress is on the second syllable in ‘preferring’. However, we don’t double the ‘r’ when adding ‘-ence’ since we stress the first syllable in ‘preference’.

There are also 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.

With ‘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.

On top of this, American English is noteworthy for not doubling the final consonant in certain words that end in ‘l’. This isn’t the case in Australian English, though, so make sure to double the ‘l’ in words like:

Base Word

American English

Australian English


Traveled, Traveling, Traveler

Travelled, Travelling, Traveller


Canceled, Canceling

Cancelled, Cancelling


Modeled, Modeling, Modeler

Modelled, Modelling, Modeller

In 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, if you’re not sure you’ve spelled something correctly, having your work proofread is a great idea.

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