How Much Does It Cost to Build an App? A Worked Example

Every explanation of app development cost you've read so far has either scared you or shrugged at you. The scary version quotes a headline range with three commas in it, for an app that doesn't exist yet. The shrug version says "it depends" and stops there. Neither one actually shows you how much does it cost to build an app — and how that number moves when you swap one feature for another. So here's the thing I haven't seen anywhere else: one actual spec, priced feature by feature, worked all the way through — no dollar figures required.

If you want the general drivers first, what actually moves mobile app development cost covers the six variables and three scope tiers this worked example maps onto. This article assumes you've read that, or don't need to — it exists to answer a narrower question: given one specific spec, where does it land, and what would move it.

The spec we're pricing

Call it Fictional-Composite, because it isn't any client's real app — it's a composite built to be representative. A subscription mobile app, single Flutter codebase shipping to both stores, built around one AI-assisted core feature (think a recommendation or coaching screen, not a chatbot) plus a personal-progress dashboard. Email and Sign-in-with-Apple auth. One paywall, one subscription tier. Push notifications for re-engagement. A 10–15 event analytics taxonomy from day one.

This is a cost to build an app example you can actually map onto your own idea, rather than a category-level average that tells you nothing about your specific spec. If your idea has more or fewer of these pieces, you can slide it up or down the bands below. If you haven't written your own spec down yet, scope it in sixty minutes first — this worked example is what the output of that exercise looks like once you price it.

Mapping the spec onto the three tiers

The pillar article on mobile app development cost sets out three scope tiers — Validation, Founding, Production — that differ by surface, not by quality. Fictional-Composite is not a Validation-tier build. A single paywall, an AI-assisted feature, a full analytics taxonomy, and post-launch stabilisation already put it in Founding-tier territory: roughly double a Validation-tier build's surface, with several integrations working together instead of one or two in isolation.

It is not Production-tier either. There's no multi-tier billing, no native modules, no custom backend. If you're trying to work out how much does it cost to build an app like this one, Founding is the tier to budget against — not the scary headline number and not the cheapest quote you received.

Pricing the feature stack, band by band

Treat each piece of the spec as a multiplier on a baseline, the same way the pillar article treats platform count (one Flutter codebase at 1.0x, two native codebases closer to 1.7x, because you're maintaining two of everything).

• Auth (email + Sign-in with Apple). Close to baseline. Apple mandates Sign-in-with-Apple whenever another social login exists, so this isn't optional once you add Google or Facebook auth — budget it in from day one rather than discovering the requirement at App Store review.
• The AI-assisted core feature. This is where the integration-surface driver shows up hardest. A single well-scoped AI feature behind a clean provider abstraction is a moderate lift. The same feature without an abstraction layer — direct calls scattered across screens — is cheaper today and meaningfully more expensive the day you need to swap models. For the full picture of how AI features change the cost equation — including the recurring API-usage cost this one bullet doesn't cover — see AI app development cost.
• Personal-progress dashboard. Mostly UI implementation — the largest line item on almost any project, because every state (loading, empty, error, success) has to be built, not just the happy path.
• Push notifications + analytics taxonomy. Individually small. Together they're the difference between a founder who can see what's happening in the funnel and one who's guessing, and they're cheap to build correctly now versus expensive to retrofit later.
• Both app stores. Baked into the Flutter choice. Two native codebases would push this spec toward the Production tier on cost alone, before adding a single feature.

Add those bands together and you get a shape, not a number — which is the honest answer to how much does it cost to build an app once you stop asking about a category and start asking about a spec.

What doesn't move the number much

It's worth naming what's absent from the list above, because founders often assume these drive cost more than they do. Choice of state-management pattern inside Flutter, choice of managed backend (Firebase versus Supabase), and cosmetic design polish on top of an already production-grade Figma file are all close to cost-neutral at this scope. They shape maintainability and long-term velocity, not how much does it cost to build an app in the first place. Where a founder's instinct to economize actually saves money is dropping a feature from the spec — where it backfires is picking a junior engineer to build the same spec cheaper, because the missing judgment shows up as the rewrite tax eighteen months later, not as a lower invoice today.

What a subscription paywall specifically adds

If you're asking how much to build a subscription app specifically — rather than a free utility with no billing at all — the paywall is usually the single feature most likely to move your spec up a tier. One subscription tier, one price point, standard App Store and Google Play billing: that's the baseline assumed above. Add a second tier, a free trial with its own edge cases, or a parallel web-based subscription alongside store billing, and you've meaningfully changed the spec — that's a Production-tier billing conversation, not a Founding-tier one.

Two proof points, no price tags attached

I've shipped comparable specs before, and the timelines are real, even if the prices aren't published here. Boyfi — an AI companion app with dual subscriptions across iOS and Android — went live on both app stores six weeks after kickoff, which is squarely Founding-tier pacing for a spec with more billing complexity than Fictional-Composite carries. MyCoach has run two years and sixty-plus updates without a single rewrite of its core architecture, which is what the "stabilisation and hand-over" line in a quote is actually buying you — not a nice-to-have, but the reason the codebase survives past month four.

Where this spec would move up or down a tier

Push it toward Production: a second subscription tier or a parallel web-and-store billing setup, a native module (HealthKit, Bluetooth, camera-heavy AR), real-time chat or video instead of the single AI-assisted screen, or splitting the single Flutter codebase into two native ones.

Pull it back toward Validation: drop the AI feature to a single static recommendation rule instead of a live provider integration, cut the analytics taxonomy to the 3–5 events you'd need for a go/no-go decision, or ship without push notifications until you've validated retention is worth building for.

Neither direction changes the engineer or the standards. It changes how much product surface and integration work you're buying at that standard — which is really the only honest answer to how much does it cost to build an app: not a single figure, but a direction you move from a known baseline.

Reading someone else's quote against this example

Use this the next time you're handed an app development cost estimate: ask which of the bands above the quote is pricing at Founding-tier effort, and which it's quietly pricing at Validation-tier while describing a Founding-tier spec. I've seen two proposals for what was supposed to be the identical spec land three times apart, because one of them quietly excluded stabilisation and integration testing and the other didn't — same feature list, wildly different actual scope once you read the fine print.

A quote that's dramatically lower than everything else you've received usually means a line item like this got dropped, not that you found a better price for the same spec. How AI-augmented delivery actually works explains why AI tooling changed the timeline on a spec like this one without changing the judgment that priced it — a faster build isn't a cheaper build.

Why there's still no dollar figure here

Because Fictional-Composite isn't your app. Your version might swap the AI feature for something simpler, or add a second platform integration I haven't priced, and either change moves the number more than any average could predict. What this worked example gives you instead is a way to check your own spec, feature by feature, against the same bands a real quote should be using.

If you want to run this exact exercise against your actual spec, tell me about the project — mapping your feature list onto these tiers takes one conversation, not a guess dressed up as a price list. That conversation is also the fastest way to get an actual answer to how much does it cost to build an app you're specifically planning, instead of one that describes Fictional-Composite.