Build vs buy calculator
Compare building an agent in-house against buying a verified one, over the horizon you actually plan to. Includes upkeep, which is the line every build case leaves out and the line that decides the answer.
The thing most people get wrong
Set upkeep to zero and building always wins. That is the assumption every build case quietly makes, and on this kind of software, where models change under you and an upstream API can change shape in a week, it is never true.
How to use it properly
- 1Use a loaded day rate, not a salary divided by working days. Whatever your finance team uses for contractor comparisons is the right number; it is usually between 1.4 and 2 times the naive figure.
- 2Estimate build days and then apply your own historical multiplier. If your last four internal tools each took twice their estimate, the honest input is twice your estimate.
- 3Upkeep is the input worth arguing about. One to two days a month is normal for something that calls a model and a third-party API; zero is not a number, it is a wish.
- 4Read the payback month. If it falls outside the horizon anyone in the room can actually commit to, the build does not pay back, regardless of how it feels.
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