How Much Does It Cost to Build an App in the UK?

It's a fair question and a genuinely hard one to answer honestly, because the truthful answer is 'it depends', and anyone who gives you a confident number before understanding what you actually need is either guessing or selling you something. What we can do here is explain what the cost actually depends on, so a number, when you do get one, makes sense rather than feeling arbitrary.

What actually drives the cost

• How many distinct things it needs to do: a booking system with a calendar, notifications and payments is a fundamentally bigger job than a single-purpose form, even if both feel "simple" to describe.
• Whether it needs a mobile app, a web app, or both: a native mobile app for iOS and Android roughly doubles the platform-specific work compared to one well-built web app, unless the two are built to genuinely share the same underlying platform.
• How much of it is custom versus how close an off-the-shelf tool gets you (see our guide on custom software vs off-the-shelf): custom work costs more per feature, but only because it does exactly what you need rather than what a generic tool happens to offer.
• Integrations with other systems: connecting to payment providers, accounting software, existing databases or third-party APIs each add real work, testing and ongoing maintenance.
• Data sensitivity and compliance needs: an app handling health information, financial details or anything covered more strictly under UK GDPR needs more care in its design, which takes more time to get right.
• How polished the design needs to be: a functional internal tool for your own team and a consumer-facing app competing for App Store attention have very different design budgets, reasonably.
• What happens after launch: ongoing hosting, monitoring, updates and support are a real, recurring cost, not a one-off (see our guide on what happens after your app launches).

How the cost is usually structured

Most UK software work is priced either as a fixed quote for a defined scope, or on a time basis (day rate or sprint-based) when the scope is still being worked out. Fixed quotes are reassuring but only work well once requirements are genuinely clear; pricing something vague as fixed usually means padding for the unknowns, which you end up paying for either way. A good software company will tell you honestly which situation you're in, rather than forcing a fixed number onto a fuzzy idea.

We deliberately don't publish a generic price list on this site (see our guide on what to prepare before approaching a software company): every serious quote should come from an actual conversation about what you need, not a menu of packages that half-fit. That's not evasiveness, it's the only honest way to price custom work.

How long it actually takes

Timeline follows the same logic as cost, because it is largely driven by the same factors: scope, platforms, integrations and how much needs to be custom-built. A few honest reference points, for a UK small business context specifically:

• A focused MVP, built to prove a specific idea with a small number of core features, is often realistic within a small number of weeks once requirements are settled, particularly when AI-assisted development is used to speed up the build.
• A fuller platform, with proper accounts, a real database, payments and an admin console for your team, is a bigger undertaking, more often months than weeks.
• Anything involving App Store or Google Play submission adds review time you do not fully control (see our guide on how to publish an app), typically extra days to a couple of weeks per platform, on top of your own build timeline.
• Nearly every project loses time to requirements changing once people can actually see and use something real. That isn't a failure of planning, it's normal, and it's one of the reasons an MVP-first approach tends to save time overall rather than cost it.

The single biggest lever: how clear your requirements are

More than almost any other factor, cost and timeline are driven by how well-defined your requirements are before work starts. A clear brief, even a rough one, lets a software company scope accurately and price fairly. A vague brief forces guesswork, which shows up later as either a higher price to cover the risk, or scope creep that stretches the timeline. Time spent clarifying what you actually need before you approach anyone is close to the highest-value time you can spend on the whole project.

If you have a rough idea of what you want to build and would like an honest view of what it would actually cost and take, that conversation costs nothing to start, and a proper answer is always better than a guess from a price list.