Mobile budgets fail in a predictable way. The build is quoted, approved and delivered roughly on target, and then the app quietly costs 20-35% of the build price every year afterwards just to keep working. That recurring line is not optional and it is not maintenance in the usual sense - two operating systems ship annual releases, two stores change their review rules, and the SDKs you depend on deprecate on their own schedule. Here is what each of those actually costs.
01Build cost by app shape
These ranges assume a senior team, production quality with automated tests and CI, both platforms shipped, and a real backend rather than a mocked one. They exclude your own staff time, app store fees and paid infrastructure.
The single biggest driver is not screen count. It is how much the app has to do while the network is unavailable, and how much native device capability it touches. An app that reads from an API and renders lists is cheap on any technology. An app that must work offline, sync conflicting edits and use the camera, Bluetooth or background location is a different category of work.
| App shape | Cross-platform | Native (both platforms) | Duration |
|---|---|---|---|
| Content or catalogue app, online only | $45k - $90k | $80k - $160k | 2 - 4 months |
| Transactional app with accounts and payments | $90k - $170k | $150k - $300k | 4 - 6 months |
| Field app with offline sync | $140k - $260k | $220k - $420k | 5 - 9 months |
| Hardware-integrated (BLE, scanners, wearables) | $180k - $350k | $240k - $500k | 6 - 10 months |
| Regulated (health records, payments in-app) | $200k - $400k | $300k - $650k | 7 - 12 months |
02Native versus cross-platform, on the numbers
The cross-platform saving is real but consistently overstated. Vendors quote a single codebase as if it halved the work; in practice you save on feature code and save nothing on platform-specific work - store submission, push notification behaviour, permissions dialogs, background execution rules, deep linking and accessibility all still need doing twice in effect, even if they are written once.
The realistic saving for a mainstream business app is 25-40% against building two native apps, not 50%. That saving shrinks as the app touches more native capability, and inverts once you need enough bridging code that you are maintaining three things instead of two.
| Approach | Build cost index | Fits when | Turns expensive when |
|---|---|---|---|
| React Native | 0.65 | Team already writes TypeScript | Heavy native modules, complex gestures |
| Flutter | 0.65 | Design-led UI, consistent across platforms | Deep OS integration, large native SDKs |
| Native Swift + Kotlin | 1.00 | Performance or OS features are the product | Two teams, two release trains |
| Native on one platform only | 0.50 | Audience is genuinely single-platform | You are wrong about the audience |
| Web wrapper / PWA shell | 0.30 | Content delivery, no device features | Anything requiring offline or hardware |
03The maintenance line nobody puts in the business case
A mobile app is not a website. You cannot leave it untouched for a year and expect it to still install. Both Apple and Google raise minimum SDK targets on a schedule, and an app that misses one becomes unsubmittable - which means a security fix you need to ship urgently is blocked behind an upgrade you deferred.
Budget 20-35% of the original build cost per year as steady-state maintenance for an app under active use. That number is not padding; it is the sum of specific, dateable obligations.
| Item | Typical annual cost | Can you skip it |
|---|---|---|
| OS major-version compatibility (iOS + Android) | $12k - $30k | No - breaks on user upgrade |
| Store policy and minimum SDK target updates | $6k - $15k | No - blocks submission |
| Third-party SDK upgrades and deprecations | $8k - $20k | No - security and API sunsets |
| Device and OS test matrix maintenance | $5k - $18k | Partially, at rising defect risk |
| Crash triage and production support | $10k - $40k | No |
| Certificate, provisioning and account admin | $2k - $5k | No - expiry takes the app down |
04Costs that appear after launch and were never quoted
The build quote covers building. Several substantial costs sit outside it and land on whoever forgot to ask.
- Backend and infrastructure: $300 - $4,000/month at modest scale, more with media or real-time features.
- Push notification infrastructure and the analytics to know whether they worked: $200 - $1,500/month.
- App store optimisation, screenshots and localised listings: $3k - $12k initially, refreshed yearly.
- Accessibility remediation if it was not built in: $15k - $50k retrofitted, near zero if done during build.
- Release management: 2 - 8 hours per release once you account for review, staged rollout and monitoring.
- A second app for a different user type - admin, driver, technician - which is usually discovered in month four.
05How release cadence changes your cost base
Web teams ship continuously and treat a bad release as a five-minute rollback. Mobile has no rollback. Once a build is on a user's device it stays there until they choose to update, and store review adds a delay you do not control.
That single constraint changes what quality costs. Mobile teams need higher pre-release confidence than web teams, which means more automated testing, staged rollouts, remote configuration to disable features without a release, and forced-update mechanics for the cases where a version genuinely must die. Budget these as build scope, because retrofitting remote config after a bad release is a fire drill.
- Remote configuration and feature flags, so a broken feature can be turned off without a store submission.
- Staged rollout discipline - 1%, 10%, 50% - with crash-rate gates at each step.
- A forced-update path with a clear minimum supported version policy.
- Backend API versioning that assumes old app versions will exist for at least 12 months.
06What to ask before signing a mobile quote
The questions below separate a quote that covers a shippable, maintainable app from one that covers a demo which happens to run on a phone.
- Who owns the Apple and Google developer accounts, and are they in our name from day one?
- Are signing certificates, keystores and provisioning profiles handed over, with documented rotation?
- What is the device and OS test matrix, and who maintains it?
- Is store submission, review response and staged rollout included, or billed separately?
- What is the quoted annual maintenance, itemised - not a percentage placeholder?
- Does the quote include accessibility, or is that a later project?
Topics
Marcus Hale
Lead Architect · SyncTrix
Writes about the engineering decisions behind production systems - architecture, delivery and the trade-offs that only show up at scale.
Building something like this?
SyncTrix engineers AI, SaaS, platform and cloud systems for enterprises and high-growth teams. Tell us what you're shipping and we'll scope it with you.