Most custom mobile apps built in the UK in 2026 land between £15,000 and £150,000. If that top figure makes you wince, remember what "a mobile app" usually hides: it's an iPhone app, an Android app, a server behind them holding the data, and the not-small task of getting both through Apple's and Google's review processes. You're rarely paying for one thing.
The rough bands for 2026
| Type of app | Typical UK cost | Rough timeline |
|---|---|---|
| Simple app / MVP (one core feature, one user type) | £15k – £35k | 6–10 weeks |
| Growing app (accounts, payments, notifications, backend) | £35k – £80k | 3–5 months |
| Complex app (multiple roles, live data, integrations) | £80k – £150k+ | 5–9 months |
These overlap with — and sit a little above — the ranges in our guide to what a web app costs in the UK, and that gap is the whole story of mobile.
Why "the same app" costs more on mobile
Three things push the number up compared with a website doing the same job:
- Two platforms. iPhone and Android are different systems. Build each fully natively and you're doing much of the work twice.
- App-store approval. Apple and Google both review your app, enforce rules, and can reject it. Handling submission, compliance and updates is real, recurring work a website never involves.
- Device reality. Hundreds of screen sizes, OS versions, permissions, offline states and "what happens when the signal drops" — all things a browser hides from you and a phone doesn't.
The single biggest cost lever: native vs cross-platform
This one decision moves the budget more than any feature. Fully native means separate iOS (Swift) and Android (Kotlin) codebases — best-in-class performance, roughly double the build. Cross-platform (React Native, which we usually reach for) means one codebase that ships to both stores, cutting cost and time substantially while feeling native to users for the vast majority of apps.
Unless you're building something graphically intense — a game, heavy AR, cutting-edge camera work — cross-platform is usually the right call. It gets you onto both iPhone and Android for close to the price of one, and you can always go native later for a specific screen if you truly need to.
The cost people forget: after launch
A mobile app is never "done". Apple and Google ship new OS versions every year that can break things; both stores require periodic updates or they'll pull your app. Budget for ongoing maintenance — realistically 15–25% of the build cost per year — from day one. A quote that ignores this isn't cheaper; it's incomplete, a point we make in our guide to choosing a development agency.
How to keep it affordable
- Start cross-platform. One codebase, both stores. This alone can halve your build.
- Ship a real MVP first. Launch the one feature that proves demand, then invest in the rest — the approach we lay out in from idea to MVP in 8 weeks.
- Ask if you even need an app yet. A fast, mobile-friendly web app can validate the idea for less, and you build the native app once you know people want it.
The bottom line
Budget £15k–£35k for a sharp first mobile app, £35k–£80k for a proper product, and into six figures for a genuine platform — plus maintenance every year after. Choose cross-platform unless you have a specific reason not to, launch small, and you'll get onto people's phones for far less than the scary end of that range.