How much does it cost to add multi-language support?

The cost to add multi-language support sits in a category of app features that look cheap and are not. Founders hear “we just need Spanish and French too” and picture a translator and a weekend. The translation really is cheap. What costs money is the engineering that has to exist before a single translated word can appear in the right place, in the right format, without breaking the layout. In a UK app the total runs from about £2,000 to retrofit one extra language into a well-built app to £20,000 for a full localisation pipeline across several languages including a right-to-left one.

For where this sits against everything else in a build, our UK app development cost guide gives the full picture. This post explains what actually drives the multi-language number.

The short answer

If your app was built with localisation in mind, adding a language is mostly translation plus testing, often £1,000 to £3,000 per language. If it was not built that way, you first pay to make the app capable of multiple languages at all, which is £6,000 to £15,000 of engineering before translation even starts. That single fact, built-in versus retrofitted, explains most of the range you will see in quotes.

Why the translation is the cheap part

A typical app has a few hundred to a few thousand short strings of visible text. Getting those professionally translated into one language costs somewhere in the low hundreds to low thousands of pounds, depending on word count and whether you want a specialist in your domain. Machine translation is near free but reads badly and will embarrass you, so most serious apps pay a human to at least review it.

So if translation is cheap, where does the money go. It goes into four engineering problems that have nothing to do with language and everything to do with software.

Driver one: pulling the strings out

In a lot of apps, especially MVPs built quickly, the text is hard-coded directly into the screens. “Welcome back” is typed into the code wherever it appears. To support languages, every one of those strings has to be extracted into a separate file that can be swapped per language, and the code rewired to look text up rather than contain it.

This is the retrofit tax. On a mature app with text scattered through hundreds of screens, finding and extracting every string, including the ones hidden in error messages, buttons, and notifications, is slow, careful work. It is why adding languages to an app that never planned for them costs far more than you would guess from the word count. Build it in from the start and this cost nearly disappears, which is the same lesson as offline mode: the architecture decisions made on day one set the price of every feature you bolt on later.

Driver two: layout that refuses to behave

Translated text is almost never the same length as the English. German runs long, often 30 percent longer, and cheerfully overflows buttons designed for English. Some languages run short and leave awkward gaps. A design that looked perfect in English breaks in ways you only see once the real translations go in.

Fixing this means building flexible layouts that stretch and reflow gracefully, then checking every screen in every language. The more screens and the more languages, the more this testing effort multiplies. It is unglamorous and it is a real line in the budget.

Driver three: dates, numbers, and currencies

Language is only half of localisation. A properly localised app also formats dates, numbers, and currencies for each region. The UK writes a date one way, Spain another, the United States another again. Decimal separators flip between commas and points. Prices need the right symbol and the right position.

Getting this right is detailed work, and getting it wrong looks amateurish to exactly the local users you were trying to win. It is modest effort per case but it adds up across a full app, and it is the kind of thing cheap quotes quietly skip.

Driver four: right-to-left languages

Arabic, Hebrew, and others read right to left, and that flips the entire interface, not just the text. Navigation moves, icons mirror, alignment reverses, animations run the other way. Supporting a right-to-left language is a distinct engineering and design effort on top of adding another left-to-right one, and every screen needs a separate pass in that mode.

If a right-to-left language is on your roadmap, say so before the app is designed. Adding it later is one of the more expensive retrofits in this whole list.

A realistic cost picture

These are build costs. Remember there is a small ongoing cost too, because every new feature you ship afterwards also needs translating, so localisation becomes a permanent line in your monthly running costs rather than a one-off.

The decision that saves the most money

The biggest lever is timing. If you are reasonably sure you will need multiple languages within a year, build the structure in from the start even if you launch in English only. The up-front cost is small and it turns every future language into the cheap scenario rather than the expensive retrofit.

If a second language is only a distant possibility, it is fine to defer. Just ask your developer to keep the code structured so the text can be extracted later without a rewrite. That one instruction, given early, is the difference between a £2,000 future and a £15,000 one.

What to do next

Adding multi-language support is cheap if you planned for it and expensive if you did not, and the translation is never the thing that costs. Decide early whether languages are in your future, and if they are, pay the small up-front cost to build the capability in.

If you want a quote that separates the translation from the engineering so you can see exactly what you are paying for, send us a project brief. We will tell you honestly whether to build it now or leave the door open for later.