Translating numerals is more complicated than it seems. The number 20.525, for example, would be just over 20 in English, but more than twenty thousand in German. But that is just the beginning. There is a chaotic variety of conventions for writing numerals in different languages. Let us start exploring.
Historically, there was a fairly simple rule for translating numerals between English and German. English has a comma as the thousands separator and a dot (full stop) as the decimal point. German uses a dot (point/full stop) to separate the digits in thousands, and a comma to signify decimals. Therefore:
English 100,000,000 becomes German 100.000.000
English 23.52 becomes German 23,52.
Swiss German is a special case. Thousands are often written with an asterisk to separate groups of three digits, i.e. as 100’000’000. And there are special rules for decimals in Swiss German. General numbers with decimals are usually written with a decimal comma (23,52), but currencies are written with a decimal point (23.52).
This is where things get complicated. As early as 1948, the international standardisation body “General Conference on Weights and Measures” defined how numerals should be written. It stated that “the decimal marker shall be either the point on the line or the comma on the line”. In other words, the institute was unable to decide between the different national traditions and left both of them in place. But it was far stricter with numbers above a thousand. It stated that the groups of three digits should only be divided by spaces (e.g. 100 000 000), and that “neither dots nor commas are ever inserted in the spaces between groups“.
Never dots or commas? Seventy-five years later this utopia has still not been achieved. In the German source texts which I translate, I now see three different conventions for numbers over a thousand (100.000.000, 100’000’000 and 100 000 000). In English I see two conventions in Internet texts and printed books (100,000,000 and 100 000 000).
This is partly due to the eternal tension between natural language development and centralised language control. Many people have never heard of the standardised regulations, or they do not accept that a centrally imposed convention should take precedence over their traditional patterns. But even the official statements made by standardisation authorities, publishers and other major institutions show a surprising variety.
Different standards and style guides
The German DIN standards DIN 1333, DIN 5008 and ISO 80000 state that the thin space is the correct form in German, but the use of a dot to separate thousands is permitted for amounts of money.
The EU interinstitutional style guide requires that a space must be used to group the digits in thousands in English, and it prohibits the use of a comma.
The house style of the British Office for National Statistics states: “Use commas to separate thousands ... and never spaces”.
The style manual of the Australian government also stipulates commas to separate thousands, and forbids the use of a non-breaking space.
The Chicago Manual of Style also stipulates commas as the thousand separator.
Oxford University Press issues a mini style checklist for its academic journals. For “HUMSOC” (humanities and social sciences) it prescribes commas as the thousand separator, but for “SCIMED” (science and medicine) it prescribes thin spaces.
Wikipedia: the English style manual stipulates that digit groups should be separated either by commas or by “narrow gaps” (i.e. as 100,000,000 or 100 000 000). The use of narrow gaps is particularly recommended for articles on science, technology, engineering and mathematics. The German style manual only suggests the use of dots (100.000.000) and states that the use of non-breaking spaces is controversial within the German Wikipedia organisation.
The Microsoft globalization documentation states that the thousands separator is a comma in the USA, a dot in Germany and a space in Sweden.
What sort of “spaces between groups”?
Care is needed if we use spaces as the separators. A normal space is not a good solution, because the number could easily be split in a normal paragraph, e.g. 100 000 (line break) 000. Therefore, the space must at least be a non-breaking space (CTRL-Shift-Space). But most regulations state that it should be a “thin space”, otherwise known as a “narrow no-break space” (German: schmales geschütztes Leerzeichen). Typographers can create this space character as “U+202F”, on my computer I can create it with “Alt-8239”.
What should translators do?
The decimal marker (point or comma) is fairly clear: follow the traditional convention of the target language. The thousand separator is more complicated. Translating into English, I would use the traditional format (with commas for thousands) unless I have specific information that the other convention (with thin spaces) should be used. For translations into German, the simple answer is “it depends”. In texts for casual readers and in financial texts I would tend to use the traditional form (with dots) unless there is a specific reason to use a different version. In academic and formal texts, the standardised “thin space” is probably best. For Swiss German, of course, specific knowledge of the Swiss conventions for the text type and audience is needed.
This article is not exhaustive. I have not covered the formatting of dates or the grouping of digits in phone numbers, bank account numbers or other contexts. And there are many countries and languages which have completely different ways of writing numbers. Wikipedia is a useful starting point for research into the many different numeral systems in the world.