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Free calculatorBuild vs Buy Calculator
Compare the multi-year cost of building custom software against paying for a SaaS subscription — and get a clear verdict. Adjust the inputs to see it update instantly.
Build vs buy: how to decide
The decision comes down to two questions: is this capability core to your product? and what does each option cost over time? If a feature is a commodity — billing, auth, email, analytics — buying is almost always faster and cheaper. If it is the thing that makes your product different, building gives you control worth paying for.
The real cost of each option
- Buy — a recurring subscription that usually rises 5–10% per year, but starts working today with no build risk.
- Build — a large upfront cost, plus 15–25% of that cost every year for maintenance, hosting and updates.
- Opportunity cost — time your team spends building is time not spent on your core product.
- Strategic value — owning core software protects your roadmap and data; owning commodity software rarely pays off.
When building usually wins
It's the reason customers choose you.
Your workflow is genuinely unique.
Auth, billing, email, analytics.
Frequently asked questions
Should I build or buy software?
Buy when the capability is common and not a competitive differentiator — you get it faster and cheaper. Build when it is core to your product, when no tool fits your workflow, or when owning the data and roadmap gives you a real edge. Cost over a multi-year horizon is only one input; speed and strategic fit matter just as much.
How do I compare the cost of build vs buy?
Add up the multi-year cost of each option. For buy, take the annual subscription across your horizon and allow for price increases. For build, take the upfront build cost plus annual maintenance (typically 15–25% of the build cost per year) for bug fixes, updates and hosting. The calculator above does this for you.
What is a realistic maintenance percentage for custom software?
A common rule of thumb is 15–25% of the original build cost per year to keep custom software secure, updated and running. Complex or fast-moving products sit at the higher end; simple internal tools can be lower.
What hidden costs does building have?
Beyond engineering time, building adds opportunity cost (your team is not working on your core product), hiring and ramp-up time, ongoing security and compliance work, hosting, and the risk of schedule overruns. These are why buying often wins for non-core features.
Decided to build? Estimate the effort with the software cost estimator and the team with the dev team cost calculator.
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