Short answer: an AI agent's cost per run is the sum of model tokens, paid tool and browser calls, compute, the human time spent reviewing the output, and the expected cost of redoing runs that fail. Measure each part on real runs, then compare the total with what the same task costs today.
The formula
cost per run = token cost + tool/API cost + browser/compute cost + (review minutes × loaded hourly rate ÷ 60) + (rework rate × cost of a redo)
- Token cost: input tokens × input price + output tokens × output price, summed over every model call in the run (agents often make several).
- Tool and API cost: paid search, data, email or other API calls the agent makes per run.
- Browser and compute: hosted browser sessions, sandboxes or GPU time, per run.
- Review time: minutes a person spends checking or approving the output.
- Rework: the share of runs that must be redone or fixed by hand, times what that costs.
Worked example (illustrative numbers, not benchmarks)
| Component | Assumption | Cost per run |
|---|---|---|
| Tokens | 6 model calls, 40,000 input + 4,000 output tokens in total, at $3 / $15 per million | $0.18 |
| Tools | 2 paid search calls at $0.01 | $0.02 |
| Browser | 1 hosted browser session at $0.05 | $0.05 |
| Review | 3 minutes at a $90/hour loaded rate | $4.50 |
| Rework | 10% of runs redone at $6 each | $0.60 |
| Total | $5.35 |
In this example, review time is about 84% of the cost. That is typical of agents whose output a person signs off on: cutting review minutes, for example with better evals or clearer output formats, usually saves more than switching to a cheaper model.
Steps
- Pick one task and log 20 to 50 real runs: tokens per call, tool calls, session time.
- Time the human review on the same runs and record how many needed rework.
- Price each part from your own provider price sheets and invoices.
- Model low, base and high scenarios, since run-to-run variation is large.
- Compare with the current cost of the task (people time, vendor fees) to get savings per run and payback.
The Cost & ROI Calculator ($29) has these components as inputs, with low/base/high scenarios and a calibration tab for your measured runs.
FAQ
What is an AI agent's cost per run?
The fully loaded cost of one task run: model tokens, paid tool and browser calls, compute, the human time spent reviewing the output, and the expected cost of reworking runs that fail.
Why include human review time?
For most business agents a few minutes of reviewer time costs more than the model tokens, so leaving it out understates cost per run.
Where do the prices come from?
From your own provider price sheets and invoices. The numbers on this page are illustrative only.