When to Write Out Numbers in English Writing

One of the most common sources of discussion amongst writers and editors is when should one write out numbers in the whole, and when should one just use numerals.

This is most often an issue with regard to academic writing, although it comes up often enough in fiction writing too. If you are writing a journal article or dissertation then be sure to check with your relevant style guide for their exact rules. Many require everything to be written out whole, while others require everything in numerals, and yet another has strict rules regarding what numbers are written out and which are to be written in numerals.

There are some general rules, however, which can be followed as a default. They are also useful for fiction writing too.

The first is to always be consistent, if you are going to use numerals, use them throughout. Don't chop and change between numerals and written numbers, unless specified by your style guide, of course.

Generally speaking, dates are always written using numerals. For example:

He was born June 10th, 1967.

The book was published in 1987.

The exception being when you are referring to centuries or specific eras. For example:

It was the fashion of the nineties.

In the late nineteenth century, it was commonplace to have a private income.

Furthermore, if you can write the number out in two words or less then you write it out. For example:

There were ninety people in the class.

Out of sixty three people, only he was chosen.

There were a hundred and thirty people in his cohort.

If it would take more than three words, the number is written using numerals. For example:

There were 265 people in the audience.

When a number uses a decimal point, or refers to amounts, the number is typically written using numerals. This includes currency. For example:

The dress cost $40.50 at the shop, but I got it for $20.30 at the market.

The baby was born weighing 7.4 pounds.

Identification numbers are also written using numerals. For example:

He stayed in room 4.

Henry VIII had six wives.

Page numbers are also written using numerals:

The sentence you are looking for is on Page 50.

As are numbers in addresses:

I live at 40 MacIntyre St.

Time is a bit more difficult. Sometimes the numbers are written out, while others use numerals. Generally speaking, twenty-four hour time uses numerals, while analogue time doesn't - but there are of course exceptions. These are depending upon the style-guide and how exact you want to be. For example:

Dinner will be served at half-past seven.

The train will arrive at 1900.

The post arrived at exactly 7.34pm.

There are other rules to observe to. Again, always be sure to check with your relevant style guide - but here are some more general observations.

Always write out the number at the start of a sentence. For example:

Forty per cent of the class failed the exam.

In other contexts, percentages are written using numerals. As are other statistics. For example:

The class average was 67 per cent.

The average age was 17.5 years old.

These are of course general rules, and you should always check with your academic style guide and/or publisher to be truly sure as to when and how to write numbers. This is why editing can be so very useful, to ensure every single number is expressed correctly and consistently.