How to Plan and Estimate Android App Development

"How long will the app take?" is impossible to answer well from a one-paragraph idea, and dangerous to answer quickly. Good estimates come from breaking the work down, including the invisible parts, and communicating ranges with stated assumptions.

The estimation process

1. Discovery questions

• Who are the users, and what are the 3–5 core flows?
• Does a backend exist? Who builds it? What APIs are ready?
• Offline requirements? Accounts? Payments? Notifications? AI features?
• Design status: wireframes, final designs, a design system?
• Supported devices: phones only, or tablets and foldables? Minimum Android version?
• Languages, accessibility and compliance requirements?

2. Break down, including hidden work

3. Size items as ranges

data class Estimate(val optimisticDays: Double, val likelyDays: Double, val pessimisticDays: Double) {
    /** PERT-style weighted mean: biases toward the likely case while accounting for risk. */
    val expected: Double get() = (optimisticDays + 4 * likelyDays + pessimisticDays) / 6
}

val items = mapOf(
    "Login + Credential Manager" to Estimate(2.0, 3.0, 6.0),
    "Product list with paging + cache" to Estimate(3.0, 5.0, 9.0),
    "Checkout with Play Billing" to Estimate(4.0, 7.0, 14.0),
)
val total = items.values.sumOf { it.expected }   // communicate as a range, not a single number

Wide ranges signal uncertainty. Narrow them by spiking risky items (a quick prototype of the payment integration, for example) before committing.

4. Adjust for risk

• Add explicit buffers for unknown APIs, new technologies, and dependencies on other teams.
• Account for calendar time you don't control: Play review, closed-testing periods, client feedback cycles.
• List assumptions ("backend APIs ready by week 3", "designs final before development") so that changes are visible.

5. Plan in milestones

1. Foundation: architecture, CI, auth, design system.
2. Core flows: the 2–3 flows that define the product, end to end.
3. Completion: secondary features, edge cases, offline.
4. Hardening: testing, performance, accessibility, policy forms.
5. Release: closed testing, fixes, staged rollout.

Communicating estimates

• Give ranges with confidence levels, not single dates.
• Separate "MVP" from "nice to have", and let stakeholders choose trade-offs.
• Re-estimate at each milestone, and report changes early.

Examples

Frequently asked questions

Conclusion

Reliable estimates come from discovery, a breakdown that includes hidden work, ranged sizing, explicit risk buffers and assumptions, and milestone-based re-estimation, communicated as ranges stakeholders can make trade-offs with.

Next step: prepare for the job market with Top 50 Android Interview Questions and Answers.