Build vs Buy AI Calculator
The total cost of building a custom AI system against buying a product, over your time horizon, and the month building starts to win.
- Free
- No signup
- Formulas shown
Build vs Buy AI Calculator
Horizon
Software you build has to pay back inside this window.
Build
Include design, integration, evals and deployment.
Used for build and for your integration time.
A planning assumption. Use your own history if you have it.
Price model usage with the AI model directory.
Buy
Use a real quote.
Priced at the blended hourly cost.
Applied at each 12-month mark.
Result
Updates as you type.
Building catches up with buying at month 39 and costs no more from then on, 15 months after your horizon. Upfront build cost is $32,000, then $833 a month to run and maintain.
- Build, cumulative
- Buy, cumulative
Dashed lines: your horizon (month 24) and the month building stays cheaper (month 39). The chart runs to month 48, so the crossing is always visible.
The formulas
- Build upfront
- = build hours x hourly cost
- Build monthly
- = build upfront x maintenance % / 12 + infrastructure
- Build total
- = build upfront + build monthly x months
- Buy total
- = setup fee + integration hours x hourly cost + monthly subscriptions (subscription rises by the yearly increase every 12 months)
- Break-even
- = the month from which build stays at or below buy (checked to month 120)
If building wins on your numbers, we build it and keep it running. Custom software development
What drives the number
Building costs more up front and less each month. Three inputs decide where the lines cross.
Build hours
The upfront cost is hours times the hourly rate. Builds often take longer than planned, so try the result with more hours too.
The monthly gap
Break-even comes from the difference between the subscription and what the build costs to run each month. A small gap pushes it out by years.
Your horizon
A build has to pay back inside the time you will really use it. If the process may change in two years, do not plan on year four.
Questions
Build vs buy questions
How do I estimate build hours?
Ask the team or vendor who would build it for a range, then use the upper half. Include design, integration with your systems, evaluation, deployment and the first round of fixes. The default 320 hours is an example to edit, not a benchmark.
Is 20% a year for maintenance right?
It is a planning assumption, not a measured figure. If you run similar systems, use what they cost you to keep working: model and API changes, fixes, monitoring and small improvements.
What does break-even mean here?
The month from which building costs the same or less than buying, and stays that way for every later month up to ten years. A build that is only cheaper in its first months does not count, because buying wins later.
Why is break-even after my horizon?
Over the months you entered, buying costs less. If you expect to run the system longer, building may still win: the sentence under the results says how many months after your horizon that happens.
Should cost decide build or buy?
Rarely on its own. Time to value, fit with your process, lock-in, security review and who owns the system after launch often matter more. Use the result as one input.
Related tools
If building wins
We build custom AI systems and keep them running
Bring your numbers. We will check the build estimate with you and tell you what it would take to ship.