How Much Does It Cost to Build a Flutter Mobile App?

The range is wide because two Flutter apps with the same screen count can differ 3x in real work. The backend reads decide most of it. A list of records pulled from Firestore with simple filters is cheap. The moment you add real-time sync, multi-user state, or offline-first behavior, the cost climbs — conflict resolution between a device and the server is genuinely hard, not a checkbox.

The other big lever is native platform integrations. Each of these is its own small project with its own permission prompts, OS quirks, and store-review scrutiny:

• Camera / photo upload
• GPS and background location
• Push notifications (FCM is in scope; deep-linking from a push is more)
• Biometrics (Face ID / fingerprint)
• Bluetooth / NFC

A login + a few CRUD screens + push sits near the €7,000 floor. Add three of the integrations above plus offline sync and you are at the €25,000 ceiling. Nothing exotic — just more surface area to build and test on both platforms.

To stay near €7,000–12,000: scope a single, clear job-to-be-done. Use the platform's defaults — standard Firebase/Supabase auth, database, and storage instead of a custom backend. Skip tablet layouts (phone-only is in scope; tablet is excluded). Accept the framework's default navigation and components rather than pixel-matching a bespoke design. Ship v1, then learn from real users.

What pushes you toward €25,000: custom animations or custom rendering, anything game- or AR-shaped, backend API work beyond standard Firebase/Supabase usage, and enterprise device-management features — all explicitly out of scope in the base price and quoted separately. The single biggest avoidable cost is scope drift: "can it also do X" repeated five times across a build.

The codebase itself is already the saving. One Flutter codebase ships to both iOS and Android, so you are not paying for two native teams — that is what keeps the solo range so far below the €45,000–130,000 agency range.

The build quote is not the lifetime cost. Budget for these from day one:

• App store fees — Apple Developer Program is $99/year; Google Play is a one-time $25. Without these you cannot publish, and submission (signing, screenshots, listings, review cycles) adds 1–2 weeks to the timeline.
• Backend / SaaS usage — Firebase and Supabase are free at low volume but bill on reads, writes, storage, and bandwidth as you grow. A successful launch raises this bill, by design.
• Third-party services — payments (Stripe), transactional email (Resend), maps, SMS, analytics each carry their own per-use fee.
• Maintenance — iOS and Android ship breaking OS updates yearly. A live app needs SDK bumps and occasional fixes just to keep working, separate from new features.

None of these are hidden — they are the normal operating cost of a published app. Knowing them upfront keeps the post-launch budget honest.

For a defined v1, fixed-scope is the better fit. You agree the feature list, you get a single price, and the risk of estimation error sits with me, not you. Hourly only makes sense for open-ended discovery or ongoing iteration where the work genuinely cannot be specified in advance — and even then a small retainer usually beats raw hourly.

The practical pattern: fixed-scope for the build, retainer for what comes after (OS updates, small features, monitoring).

Timeline is 8–16 weeks, tracking the same drivers as cost. A focused app with standard auth, a clean data model, and one or two integrations lands near 8 weeks. Offline sync, several native integrations, and a larger surface push toward 16. App-store submission eats 1–2 weeks of that — plan for it rather than treating it as an afterthought.

Working solo and AI-augmented, I ship without the handoffs and overhead of a typical agency on this kind of project — one person who scopes, builds, and submits, with no team handoffs to slow the loop.