How we calculate this estimate

Most cost calculators start from a base price and multiply it by coefficients: one for platform, one for industry, one for complexity. That approach inflates without meaning. Two platforms and HIPAA compliance share nothing, so multiplying them together produces a number that describes neither.

Here, each answer contributes engineering hours into a named discipline bucket. Multipliers are applied only where something genuinely scales, and only to the specific bucket it scales. Dollars are calculated once, at the very end.

The second column is well below the first because the product definition, data model, API contracts, design system and most test scenarios were already paid for by the first surface. Adding Android to an iOS build adds roughly 70% of one client implementation — typically 20–30% of total project cost, not 100%.

Choosing React Native / Flutter instead collapses both mobile apps into one codebase at ×1.25 of a single native app, plus 48 hours for the native capability no framework fully covers. You still ship to both stores and still test both device matrices.

Design grows sub-linearly too, because the second surface reuses the design system and every decision inside it. The multiplier by surface count is 1 surface ×1, 2 surfaces ×1.2, 3 surfaces ×1.38, 4 surfaces ×1.52.

Head-count does not scale linearly. Doubling the team does not halve the schedule, because coordination cost rises with every person added. Team size here grows with the square root of the work — tuned so roughly 1,200 hours lands on a team of about 2 and 20,000 hours on about 9 — against a working week of 32 productive hours per person.

Phases overlap. Design starts before discovery finishes, the client build starts before the backend is done, and QA runs alongside development. The phase spans below sum to well over 100% of the schedule on purpose. Laying them end to end is the single most common reason published timelines come out at roughly twice reality.

Figures are rounded by magnitude so the output never implies precision it does not have: a $60,000 estimate rounds to the nearest $2,500, a $600,000 one to the nearest $10,000. A calculator that reports $487,213 is telling you something false about how well it knows your project.

Annual maintenance is derived rather than assumed: 15–22% of build cost as a floor, rising with each app store you ship through, each third-party integration that changes on somebody else’s schedule, and materially with a regulated security posture — capped at 28%.

This is a planning estimate and an indicative range. It is useful for sizing a budget, comparing options and sanity-checking a vendor quote. It is not a fixed development quote, and final development cost depends on finalised technical requirements.

No calculator can know your existing systems, the state of your data, how quickly your stakeholders make decisions, what your security reviewers will ask for, or how much of your scope will change once real users see version one. Those are the things that actually move a software budget, and they are discovered rather than selected from a dropdown.

Use the estimate to start the conversation, then get a fixed-scope proposal against written requirements before you commit. The result page reports its own confidence interval, and that interval widens honestly when your scope is still moving.