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Number formatting in Europe vs. the U.S.

As a freelance nonfiction editor, I work on many financial, scientific, and technical documents, and number formatting is something I always pay particular attention to. In this post, I’ll discuss this topic so that you’re better prepared to read, write, or edit documents in which numbers play a crucial role.

Numbers with multiple digits and decimals are written in different ways across the globe. For example, number formatting in most European countries is not the same as in the United States.

If you’ve ever received an invoice from a contractor in the EU, you might have noticed that some numbers are not written the same way as in America. Instead of a dot between euros and cents, you might have seen a comma. And instead of a comma as a thousands separator, you might have seen a space or a dot.

Why is the European number format different from the American? In this post I’ll answer this question and discuss the decimal point vs. decimal comma and the thousands separator to help you understand how number formatting in Europe differs from that in the U.S.

Number formatting in Europe: The decimal separator

Before diving into this topic, I want to clarify that in this article, when I talk about how the decimal separator or thousands separator is used in a country, I’m referring to the language of that country, not to how its residents or citizens format numbers when writing in English. Of course, a document written in English by someone from a country in Europe may have numbers formatted as in English. However, exceptions exist. A document that was translated into English from another language may use the number formatting of the source language, no matter how confusing that may seem to a native English speaker. Now let’s get started.

In most European countries, a comma is used to separate the integral part of a number from the decimal part. This means, for example, that three hundred euros and ten cents is written as 300,10—with a comma as a decimal marker.

In contrast, in the United States (as well as in other English-speaking countries including Australia, New Zealand, and the UK), the same amount is written as 300.10, using a decimal point.

In many countries, in their respective languages, a period appears before decimals. In other countries, including most European countries, a comma is used before decimals. And still in some other countries, both the decimal comma and the decimal period are used. For example, in British Canada the decimal point is used, whereas in French Canada a comma is used as a decimal separator.

Why do European countries use a decimal comma instead of a decimal point?

Throughout history, mathematicians have used all kinds of symbols to separate integers from decimals. These symbols include the dot, comma, inverted comma, vertical bar, horizontal line, colon, semicolon, and even number zero.

Especially in the 17th and 18th centuries, mathematicians used whichever notation seemed to strike their fancy, and so did typesetters.

Which came first, the decimal point or the decimal comma?

The decimal point, it seems, though historians of mathematics aren’t certain.

In the 16th century, Italian cartographer Giovanni Antonio Magini and German mathematician Christopher Clavius were among the first to use a decimal point in their publications.

But the person who popularized the use of the decimal point was the inventor of logarithms, Scottish mathematician John Napier. Thanks to the English translation of Napier’s treatise on logarithms, the decimal point became widespread in Britain as far back as the 17th century.

Why is the decimal comma used in most European countries?

In the 17th century, the decimal point popular in Britain was also used in continental Europe, though some preferred the decimal comma.

Things changed in the 18th century, when mathematician Gottfried Wilhelm Leibniz—the father of integral and differential calculus—introduced the dot as a symbol for multiplication: “I do not like × as a symbol for multiplication, as it is easily confounded with x”, he wrote.

Leibniz was an influential mathematician, and the dot as a multiplication sign became widespread in Europe.

But this solution created another problem: The dot as a multiplication sign could be confused with the decimal point. So, European mathematicians started to use a comma to separate decimals. The comma as a decimal separator became standard in Europe in the 19th century, and remains so today.

Why is a decimal period used in the U.S.?

American mathematicians didn’t follow the lead of their European counterparts.

In 18th century America, the cross (×) was more popular as a multiplication sign than the dot. So, the dot continued to be used to separate decimals from whole figures.

Even when in the 19th century the dot became the standard symbol for multiplication in the United States, the decimal separator didn’t change. Until today, it remains the dot on the baseline (.), and the multiplication symbol is a raised dot (·).

Who is to blame for the decimal point vs. comma confusion?

The decimal point was invented in Europe, but it’s not commonly used as a decimal separator across this continent. Instead, in most European countries the common decimal marker is the comma.

As illustrated by the story above, it seems to be Leibniz’s “fault” that today the decimal comma is popular in Europe, whereas in most English-speaking countries a decimal point is used.

Symbol for decimals in the International System of Units

If you’re writing a scientific paper or a technical document, you may need to follow the International System of Units. In the SI System, the decimal marker is either the comma or the dot, to be more precise, the point on the line. “The decimal marker chosen should be that which is customary in the context concerned.”

Writing numbers with decimals in SI System: 100,33 and 100.33 (In the United States, a dot is recommended.)

The thousands separator in Europe

When it comes to formatting numbers, the differences between the European and American systems don’t end with the decimal marker. There’s one more important difference: When writing large numbers (tens of thousands or more), in most European countries either a dot or a thin space is used to separate groups of three digits—counting from both the left and the right of the decimal separator.

For example, in Europe, we generally write three hundred thousand either as 300.000 (groups of three digits separated by a dot) or 300 000 (groups of three digits separated by a thin space). Some countries in Europe use other systems; in Switzerland, for example, an apostrophe is the thousands separator.

Whether a dot or a space is used differs by country, but in most European countries a comma is generally not used for this purpose. That would be confusing, because the comma is the most commonly used decimal separator in Europe.

In the United States, however, groups of three digits in large numbers are marked off with a comma (300,000 means three hundred thousand).

So, if your web designer in Spain sends you an invoice for 10.000,45 euros, or your project manager in Denmark sends you an invoice for 10 000,45, it means ten thousand euros and forty-five cents. A vendor in the U.S. would write the same amount as 10,000.45.

Writing large numbers in the International System of Units

According to the International System of Units, to facilitate reading, numbers with many digits (usually, at least five before or after the decimal marker) can be divided in groups of three digits by inserting a thin space. No periods or commas should be used to group digits.

Although in American English it’s correct to use commas to separate groups of three digits, if you need to follow the SI, do not use commas. Use thin spaces or no punctuation at all.

Writing large numbers in SI System:

  • Correct: 101 000,330 245 and 101 000.330 245
  • Correct: 101000,330245 and 101000.330245
  • Not: 101,000.330,245 and 101.000,330.245

Maybe the authors of style guides should take a firmer stance and emphasize the importance of such recommendations for all kinds of writing, and not just scientific writing.

European number format examples

Here is how we format currency in Europe, as well as how we format large numbers and numbers with decimals:

Most, but not all, European countries

  • 300.000 or 300 000 means three hundred thousand
  • €120.000,99 or €120 000,99 means one hundred twenty thousand euros and ninety-nine cents

A few other European countries, including the UK and Ireland

  • 300,000 means three hundred thousand
  • €120,000.99 means one hundred twenty thousand euros and ninety-nine cents

SI System

  • 300 000 means three hundred thousand
  • €120 000,99 or €120 000.99 means one hundred twenty thousand euros and ninety-nine cents

In brief: Number formatting in Europe

In most European countries a comma is used as a decimal marker, and a dot or a thin space is used to separate groups of three digits in large numbers. This is in contrast with how large numbers are formatted in the United States, as well as in the UK and Ireland, among others: the decimal marker is used as a decimal point, and a comma marks off groups of three digits in large numbers. In comparison, the SI System accepts both the decimal point and the decimal comma, but it doesn’t accept the comma as a thousands separator.

A mistake in number formatting may be costly. So, if authors from different parts of the world contribute to your document, pay extreme attention to the way numbers are formatted. A freelance editor and proofreader can check the consistency and accuracy of the numbers in your text and ensure your document is error-free. 

Do you have a document that needs editing or proofreading? Send me a message at editor@languageediting.com.

Acknowledgments: Several readers have helped me improve this post since I first published it. I am grateful to Jon, M. Payne, Steve P., and to the people who commented on a Quora post I wrote on a similar topic.

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Last revised on 1 November 2023

Cristina N.

A freelance editor and writer with a keen interest in science, nature, and communication, I love to craft articles that help and inspire people.