A British character says I paid 50 pounds for this.
Do you write J'ai payé 50 livres, or do you convert to euros so the French reader can feel the price?
The answer depends on what the sentence is actually communicating: the exact amount, or what the amount means. Money is the one category where conversion is usually the wrong instinct.
The general rule: keep the currency
In most cases, keep the original currency.
Two reasons. First, exchange rates move: a conversion that is accurate on the day of translation is wrong within months, and permanently wrong in a book. Second, the currency is part of the setting — a character paying in pounds is in Britain, and converting the sum quietly relocates them.
- The book costs 15 pounds. ↔ Le livre coûte 15 livres sterling.
- She earns $50,000 a year. ↔ Elle gagne 50 000 dollars par an.
- Coffee is $5 in Manhattan. ↔ Le café coûte 5 dollars à Manhattan.
That last one is the clearest case: the French reader understands perfectly well that five dollars is a lot for a coffee, and the dollars are what keep the scene in New York.
One refinement: livres alone is ambiguous in French, since it also means books and pounds of weight. Write livres sterling on first mention.
The typography everyone gets wrong
- English: the symbol comes before the amount, with no space — £50, $100, €20.
- French: the symbol comes after the amount, preceded by a non-breaking space — 50 £, 100 $, 20 €.
Writing £50 in a French text is a straightforward anglicism, and one of the fastest ways to make a translation look machine-made.
Two further details:
- Decimals and thousands. $19.99 becomes 19,99 € — comma, not point. $1,500 becomes 1 500 $, with a non-breaking space and no comma.
- Disambiguating dollars. Where several dollars are in play, financial French uses ISO codes: 100 USD, 100 CAD, 100 AUD. Canadian French writes 100 $ CA.
The number that is not a unit: billion
Before any monetary translation, the most expensive false friend in the language: the English billion is the French milliard. The English trillion is the French billion.
Translate a $2 billion deal as un contrat de 2 billions de dollars and you have multiplied it by a thousand, in a sentence that reads perfectly. In financial and news translation this is the error to check first, every time.
When to adapt instead
Sometimes the amount is not the message. What matters may be the order of magnitude, the symbolic weight, the emotional effect, or simply whether the reader can picture the sum at all.
Symbolic value: the Roald Dahl case
From Charlie and the Chocolate Factory:
"And in this way, Charlie would make his sixpenny bar of birthday chocolate last him for more than a month."
A literal version gives sa barre de chocolat à six pence, which tells a French child nothing: they do not know what a penny is, still less a pre-decimal sixpence. Even a footnote would break the spell.
The published translation reaches instead for a French idiom of small value — un petit bâton de chocolat à deux sous. The adaptation works because:
- the audience is children, who cannot be asked to convert anything;
- the real message is almost nothing, not six pence;
- à deux sous is immediately understood in French as meaning of little value;
- the emotion survives — Charlie is poor, and the chocolate is precious precisely because it costs so little.
Historical amounts
The dress cost five guineas. A guinea means nothing to a modern reader in any language, and converting it to euros is meaningless too, since the purchasing power of 1880 does not translate into 2026 at any exchange rate.
Two workable options: keep cinq guinées and let a note or the context carry the value, or translate the meaning — une petite fortune — if what the sentence conveys is expense rather than a figure. The first preserves period colour; the second preserves flow.
Idiomatic expressions built on money
Here you never translate the amount. You look for the equivalent expression:
- my two cents (my modest opinion) ↔ mon grain de sel
- a dime a dozen (extremely common) ↔ ça court les rues, il y en a à la pelle — note that the idea is abundance, not cheapness, and translations like trois fois rien miss it
- for a song (very cheap) ↔ pour une bouchée de pain
- Penny for your thoughts ↔ À quoi penses-tu ? — no French idiom exists, so the sense is simply stated
- to cost an arm and a leg ↔ coûter les yeux de la tête — a limb on one side, eyes on the other
Slang for money
Money has its own informal register, and it carries character. Bucks, quid, a grand, a tenner have French counterparts in balles, thunes, un bâton, une brique — though the last two are dated and tied to the franc, which is worth remembering before using them in a contemporary text.
Can you lend me twenty bucks? ↔ Tu peux me prêter vingt balles ? keeps the register, where vingt dollars keeps the setting. Which you choose depends on whether the character or the geography matters more in that line.
Keep or adapt: the summary
Keep the currency when:
- the exact amount matters — a price, a salary, a ransom, a contract;
- the setting matters and the currency anchors it;
- the readership is informed — business, economics, news;
- the text will outlive any exchange rate you might use.
Adapt when:
- the message is symbolic — expensive, cheap, a fortune, nothing at all;
- the readership cannot picture the foreign currency, children above all;
- the amount sits inside an idiom;
- the emotional effect outweighs the numerical precision.
And one technique that resolves many cases without choosing: keep the currency and add a qualifier. He left a $100 tip becomes Il a laissé un généreux pourboire de 100 dollars — the figure is intact, and the reader is told how to read it.
Three decisions
- Children's book. The candy cost 25 cents. → Le bonbon ne coûtait que quelques centimes. The figure is irrelevant; cheapness is the point.
- Crime novel. The ransom was set at $1 million. → La rançon était fixée à un million de dollars. The amount is plot, and the dollars are setting.
- Contract or financial report. Keep the currency, add the ISO code, convert nothing, and check every billion.
Conclusion
Translating money is a choice between precision and communication.
If the reader needs to know that the book costs fifteen pounds, keep the pounds. If a child needs to understand that the chocolate costs almost nothing, reach for deux sous.
The decisive question is always the same: is the message the number, or what the number represents?
Because sometimes fifty pounds stays fifty pounds — and sometimes sixpence becomes two sous.