Flutter and a single codebase: what you gain, what you don't
Writing one codebase for two platforms does not halve the cost. Here is where the savings actually are, and where the work still doubles.
"If we use Flutter, does the cost drop by half?"
No. But there is a real saving, just not where you expect it.
Where you gain
Interface code. Screens, flows, animations, form validation — written once, identical on both platforms. This is the bulk of an app's code.
Business logic. Calculations, data models, server communication, caching. Platform-independent anyway.
Consistency. When two teams build two platforms separately, small divergences are inevitable: a button that exists on one side and not the other, a different error message. A single codebase removes that class of problem entirely.
Maintenance. A bug is fixed in one place. Long term this is the biggest win — not in the initial build, but across the following two years.
Where you don't
These still cost double, single codebase or not:
Store processes. Two accounts, two sets of certificates, two reviews, two screenshot sets, two descriptions. Nothing to do with code.
Testing. You cannot assume something that works on iOS works on Android. Keyboard behaviour, the back button, permission dialogs, notification handling — all different. Both need testing on real devices.
Platform-specific features. Sign in with Apple, Android background services, widgets, payment integrations. These get written per platform. Flutter makes it easier; it does not make it disappear.
Design expectations. iOS and Android users expect some patterns to differ. Going with one design is possible and often correct — but it is a decision, not something you get for free.
So how much do you save?
The honest answer: it depends on the project, and it is not "half". In an interface-heavy app with little platform-specific work, the saving is large. In an app that lives close to the hardware, runs in the background and talks to platform services, the gap narrows.
Be sceptical of anyone who gives you a percentage. That number can only be produced after the scope is defined.
When Flutter is the wrong choice
Being honest about it:
- The app targets one platform and will stay there
- The core of the product depends on the newest platform features
- You need heavy 3D graphics or specialised hardware processing
In those cases native is the right call, and we will say so.
The decision is really about the team
Underneath the technical argument is a practical fact: building two platforms separately requires two separate specialities. For a small team that means either hiring twice or knowing everything half well.
A single codebase lets a small team ship serious work on both platforms. That is the real gain — not lines of code, but focus.