Build vs. Buy Software Calculator

Why three options, not two

Build-vs-buy content usually compares a vendor subscription against hiring a team — and hiring loses on year one every time, so the analysis quietly becomes an ad for the vendor. The real decision has a third path: a senior partner builds the system without you hiring for it. You pay the build once and a maintenance retainer after, skipping the ~25% hiring and coordination overhead and the fixed FTE cost that make in-house ownership expensive before the system justifies dedicated headcount.

The chart compares cumulative cost across five years: the vendor line compounds at your cost-growth rate; the build lines pay up front and grow linearly. Where they cross is your break-even year. Need a realistic build estimate for the comparison? Use the software cost calculator first.

Common questions

How do you calculate build vs. buy for software?

Compare cumulative 5-year cost, not sticker prices. Buy = integration cost plus the vendor subscription compounding at your seat/usage growth rate. Build in-house = the build cost plus ~25% hiring and coordination overhead, plus the fraction of an engineer's loaded cost to own it every year. Build with a partner = the build cost plus a maintenance retainer, typically 15–20% of the build per year.

When does building beat buying?

Building wins when vendor cost compounds fast (seat-priced tools at a growing company), when the system is core to your differentiation, or when data ownership and roadmap control carry real value. Buying wins for commodity capabilities at stable scale. The break-even usually lands in years 2–4 — which is why 1-year comparisons almost always favor the vendor and mislead the decision.

What does 'build with a partner' mean and why is it often cheaper than in-house?

It means a senior external team builds (and optionally maintains) the system without you hiring for it. You skip the ~25% hiring/coordination overhead and the fixed cost of dedicated FTEs — maintenance is a retainer sized to the system instead of headcount. In-house wins later, if and when the system needs multiple full-time engineers anyway.

Is it cheaper to build or buy software?

Buying is almost always cheaper in year one, because you pay a subscription instead of a build. Over five years it depends on three numbers: how fast the vendor bill grows with your seats or usage, how much the build costs, and what it costs to own the system each year. Seat- or usage-priced tools at a growing company often cross over in years 2–4; flat-priced commodity tools usually never do. Enter your own numbers above to see where your lines cross.

Should you build or buy a dashboard tool?

Buy when your dashboards are internal reporting on standard data: BI tools like Looker Studio, Metabase or Power BI cover that well. Build when the dashboard is part of your product (customer-facing analytics inside your app), when per-viewer or embedded pricing grows with your customer count, or when you need workflows the BI tool can't do. A common middle path is building the customer-facing views on top of an embedded analytics library while keeping internal reporting in a bought BI tool.

What costs does this calculator leave out?

Deliberately excluded: switching costs if you leave the vendor later, the opportunity cost of engineering attention, and vendor lock-in risk — they're real but situation-specific. If the totals are within ~20% of each other, those soft factors should decide, not the spreadsheet.

Build vs. buy guides by system

The calculator gives you the shape of the decision. These guides cover the thresholds, vendor options and hidden costs for specific systems.

• Identity platform: build vs. buy
• Authentication at scale: build vs. buy
• Consent management: build vs. buy
• Product analytics: build vs. buy
• Search: build vs. buy
• Feature flags: build vs. buy
• SaaS billing: build vs. buy
• Audit logging: build vs. buy
• Observability: build vs. buy
• Feature store: build vs. buy
• Image asset management: build vs. buy

Related: architecture & strategy · technical due diligence · build vs. buy insights