Why Two Quotes for "the Same App" Can Differ by 3-4x
Send the same one-paragraph app idea to five development shops and you will get five wildly different numbers - sometimes ₹4 lakh, sometimes ₹40 lakh, for what the client thought was an identical brief. This isn't dishonesty on anyone's part; it's because "build me an app like X" leaves dozens of cost-determining decisions unmade. Whether the backend is a shared multi-tenant service or a dedicated instance per client, whether push notifications need a message queue and retry logic or just a Firebase call, whether the app needs offline data sync with conflict resolution or just a network-error message - none of that is visible in a one-line pitch, but each choice can add or remove weeks of engineering time. This guide breaks the cost of a mobile app into the actual line items that engineers estimate against, so you can read a proposal and know what you're paying for instead of comparing bottom-line numbers blind.
The Core Cost Drivers, in the Order They Actually Get Estimated
Screen Count and Screen Complexity
Estimators typically start by counting distinct screens/states - not just "10 screens" but weighting each one. A static "About Us" screen and a checkout screen with saved cards, coupon logic, tax calculation and multiple payment gateways are both "one screen" but represent very different effort. A realistic estimate separates screens into simple (form or list, 4-8 hours), moderate (custom UI, some business logic, 1-3 days) and complex (multi-step flows, real-time data, animations, 4-8 days).
Backend and API Work
If there's no existing backend, this is usually the largest line item, not the mobile UI itself. Typical backend scope includes: authentication (email/password, OTP, social login, or SSO via OAuth2/OpenID Connect), a REST or GraphQL API layer, a database schema (PostgreSQL/MySQL for relational data, MongoDB for flexible document data), file/media storage (S3-compatible buckets with CDN delivery), and admin tooling so someone on the client side can manage content or users without a developer. Building on top of Firebase or Supabase instead of a custom backend can cut this cost significantly for simpler apps, at the cost of some flexibility later.
Native vs. Cross-Platform: The Real Trade-off
Flutter and React Native let one codebase ship to both iOS and Android, which typically reduces cost by 30-40% compared to two separate native builds (Swift/SwiftUI for iOS, Kotlin for Android) - but the savings shrink as the app leans on platform-specific capabilities: ARKit/ARCore features, deep background processing, complex custom animations, or tight integration with device hardware (Bluetooth LE peripherals, NFC payment terminals, biometric hardware modules) often need native modules bridged into the cross-platform code anyway. For content-driven apps, marketplaces, booking platforms and most B2B utility apps, cross-platform is usually the right economic call. For apps where the mobile experience itself is the product's differentiator (camera-heavy, AR, gaming, high-performance media), native often earns back its higher cost in retention and store ratings.
Third-Party Integrations
Payment gateways (Razorpay, Stripe, PayU), SMS/OTP providers, maps and geolocation (Google Maps SDK, Mapbox), push notification services, CRM or ERP connections, and social logins each bring their own SDK quirks, sandbox testing requirements and edge cases (failed payment retries, webhook verification, rate limits). Budget 1-3 days per integration even for "well-documented" APIs, because production edge cases rarely match the happy-path documentation.
Offline Support and Data Sync
If the app needs to function without a live connection - field service apps, inventory apps in low-connectivity areas, note-taking tools - local storage (SQLite, Realm, or Hive for Flutter) plus a conflict-resolution strategy for when the device reconnects is a distinct, non-trivial cost item that's easy to underestimate in a first quote.
What a Proposal Should Break Down (and Usually Doesn't)
- UI/UX design hours separate from development hours - wireframes, high-fidelity mockups, and a design system/component library if the app will grow.
- Platform split - is the quote for one platform first and the other later, or simultaneous release on both.
- QA and device testing - which physical devices and OS versions are covered, and whether automated tests (unit, widget/UI, end-to-end) are included or manual-only.
- App store submission - Apple's review process, provisioning profiles, and Google Play's data-safety and content-policy requirements each take real time and occasional rejection-and-resubmission cycles.
- Post-launch warranty period - most reasonable proposals include a fixed bug-fix window (commonly 30-90 days) separate from ongoing maintenance retainers.
Ongoing Costs That Don't Show Up in the Build Quote
Apple and Google Fees
An Apple Developer account is $99/year; Google Play is a one-time $25 registration. Small, but easy to forget in a total-cost-of-ownership conversation.
Server and Infrastructure
Hosting cost scales with active users and data volume - a low-traffic MVP might run on $20-50/month cloud infrastructure, while an app with real-time features, media uploads, or tens of thousands of daily active users needs load balancing, caching (Redis), and possibly a CDN, pushing this into a recurring line item that should be planned for from day one, not discovered after launch.
OS Update Maintenance
Apple and Google ship major OS updates annually, and deprecate APIs on a rolling basis. An app that isn't touched for 12-18 months risks store rejection on resubmission or runtime crashes on new OS versions. Budgeting a small annual maintenance retainer is cheaper than an emergency rebuild.
How Urgent IT Solution Scopes an Estimate
Rather than quoting from a feature checklist alone, we walk through the actual data model and user flows with the client first - who creates data, who consumes it, what happens when a network call fails, what the admin needs to see - because those answers change the backend estimate more than the number of screens does. We separate the quote into design, mobile client work (per platform), backend/API work, integrations, and QA/deployment, so each number can be checked against the deliverable behind it. Where a client's budget is fixed rather than the scope, we'll say plainly which features should move to a phase two rather than quietly cutting corners on testing or security to fit a number.
Questions Worth Asking Before You Sign a Quote
- Is this a fixed-price quote or time-and-materials, and what happens if a screen turns out to be more complex than assumed?
- Does the quote include source code ownership and handover, or does the app remain tied to the agency's infrastructure?
- What's included in "support" after launch - bug fixes only, or also OS-update compatibility work?
- Has the estimator accounted for both iOS review guidelines and Google Play policy separately, or treated them as identical?