Platform choice is the single biggest cost driver
A PWA is the cheapest path (one codebase, no app-store review). Cross-platform (React Native/Flutter) costs more but still shares one codebase across iOS/Android. Fully native, built separately per platform, is the most expensive — see PWA vs Native vs Cross-Platform for when each is actually justified.
What drives cost within any platform choice
Backend and API complexity (see What Backend Does a Mobile App Need?), number of user roles, third-party integrations, and whether AI features are included — the same factors that drive web application cost apply here.
App-store review and submission
Native and cross-platform apps need App Store / Google Play submission and review, which adds time (not usually large direct cost) that a PWA skips entirely.
How to get a real number
Through an App Scope conversation — platform choice alone can shift the estimate several times over, so a generic number without that decision made first wouldn't be honest.
Questions
Is a PWA always the cheapest option?+
Usually yes for the initial build — though if it later needs to be rebuilt natively, the two costs together can exceed starting native, so factor in the likely long-term path too.
Does this include ongoing maintenance?+
No — app-store fee cycles, OS updates and ongoing maintenance are typically scoped separately from the initial build.
Can I start cheaper and upgrade platform later?+
Yes — starting with a PWA or cross-platform build and moving to native later (if justified) is a common, sensible path.