The true price tag of building a custom phone OS

Nothing has pulled back the curtain on how expensive it truly is to build a smartphone operating system, putting the cost of a full build at an eye-popping $40.47 million.

The number was revealed in a deep-dive interview with creator Arun Maini (Mrwhosetheboss), and makes the roughly $26 million the team previously raised for their flagship hardware look puny, proving out a truth that industry players secretly hold: software is the long pole in the tent.

Inside the $40 million estimate to build a phone OS

Nothing’s delineation is for the entire lifecycle, from early planning to when it ships. “The planning owes nothing to chance.” The planning phase alone sees senior product, design and the architecture team mapping out required features and interface philosophies — think core layouts or motion language, how notifications should behave, etc., before a line of code has even been written.

The heavy moving here is platform development. Engineers here fork AOSP and form the system framework, services, and kernel integration. This is the intersection of power management, memory policies, permission models, sensors, the camera pipeline, and the connectivity stack. According to the estimate, engineering and design on this have been decades’ worth of effort across system UI, frameworks, kernel, and device bring-up, with well over $34 million invested.

From there, it’s testing and compliance all the way down. Automated test farms, stress and battery regressions, security validation, and user studies are all run in parallel. Costs rise with tooling, cloud GPUs for build and test acceleration, and paid user research. A 15 percent contingency is layered on top to account for inevitable scope creep and bug-fix debt, taking the total past $40 million.

AOSP versus building a smartphone OS from scratch

Nothing’s decision to develop on top of AOSP is practical. AOSP is a framework that includes mature components such as schedulers, HALs, media codecs, telephony stacks — and a door to Google Mobile Services (GMS) for when your build passes CTS and VTS compatibility tests. That bedrock compresses timelines and paves the way to the Google Play ecosystem, table stakes for most global consumers.

Starting from scratch would multiply costs and years of engineering, as is evident in Huawei’s HarmonyOS and other initiatives that attempt to reimagine the computer as a platform. Apart from writing core services, a totally new OS has to woo developers, create SDKs, set up app stores, and make sure everything from banking apps to Bluetooth devices works. The technical challenge is one half of it; the ecosystem gravity is another.

Where the money actually goes in smartphone OS builds

Line items stretch beyond code. Factor in baseband and radio co-integration with silicon from Qualcomm or MediaTek; camera tuning with vendor ISPs; and driver certification from display, fingerprint, and haptic suppliers. Both add engineering time and specialized test equipment.

Compliance is another sinkhole. If OEMs want to bundle Android with Google services, Google believes they should have to pass compatibility suites provided by Google and agree to security patch cadence. Carriers in strategic markets need network and emergency services certification, and regional statutes on privacy demand scrutiny of data handling. Veterans of the industry cite CI infrastructure, OTA update pipelines, crash analytics, and bug bounty programs as recurring costs that never go away after launch.

Then there’s localization and accessibility. The commitment to support dozens of languages as well as right-to-left scripting and assistive technologies requires dedicated efforts from teams and extensive usability testing. Even “small” UX flourishes — custom animations, glyph sets, and haptic patterns — carry real costs at scale as every tweak necessitates testing across chipsets and device variants.

Timelines and team realities behind a modern phone OS

Nothing’s roadmap maps out months of work across stages: up-front planning, six months on platform development, another long period with quality assurance (QA) and compliance testing, then device bring-up and launch polish. Industry norms back this cadence. Major OEMs typically host dozens of parallel kernel, frameworks, UI, and silicon integration teams conducting hundreds of test runs each week focusing on battery life, thermal stability, audio latency, camera performance, and 5G operation in diverse networking conditions.

Even after launch, costs continue. Security fixes, big version merges, and regression testing eat budgets for years. Google’s segment-level security bulletins and kernel LTS updates require full-time maintenance teams. For brands that promise updates for several years — an expectation set by competitors, and also of consumers — this becomes a standing line item.

Why a full operating system is not just a launcher

Nothing is explicit about what distinguishes a themed launcher from an actual OS. A launcher is responsible for icons and home screens; an OS manages system behavior end-to-end — power and memory policies, sensor fusion, background task limits, input latency, and hardware drivers. Which is why there is all the more to gain in the way of performance and battery life by deep integration, not a fresh coat of paint.

The bigger picture for new entrants building phone OSs

The lesson is harsh: hardware makes the headlines, but software consumes the budget. For startups and niche players, AOSP is the only on-ramp available to modern smartphone experiences that delivers a compliant base while providing access to must-have apps. Building an OS from the ground up is not just costly — it’s also an ecosystem problem, requiring years of runway and both a good reason for developers to take notice and motivation for users to make the change.

The estimate brings the trade-offs to life. With software costs now exceeding premium hardware bills of materials, the savvier play is to spend where users notice it most: rapid updates to stay secure, tasteful UX, bug-free performance, and adept integrations. In a space where differentiation often resides in the details, that’s money better spent.