# Tracking Usage and Setting Budgets — Claude API / OpenAI API Basics

Source: https://www.geekswithgeeks.com/en/llm-apis/c-track

> Measure per user, feature and model, and stop runaway spend.

## What you do not measure will surprise you

Every response carries **usage**. Record it per request together with the user or tenant, feature, model and prompt version, so you can answer "which feature costs most?" and "which customer is expensive?". Set **budgets and alerts** in the provider console and in your own code (a per-user daily token limit, a per-request cap, a monthly ceiling that disables non-essential features). Add **guardrails** against abuse and bugs: cap `max_tokens`, cap loop steps in agents, limit input size, rate-limit users. Review the most expensive requests regularly; they often reveal a prompt that grew too long or a loop that never stops.

## A budget guard, run

I ran this plain-Python (standard library only) example. After three calls the tracker has used 5,700 of a 6,000-token budget. A 1,000-token request would exceed it and is refused; a 300-token request fits exactly and is allowed.

```python
class UsageTracker:
    def __init__(self, budget_tokens):
        self.budget, self.used, self.calls = budget_tokens, 0, 0
    def record(self, input_tokens, output_tokens):
        self.used += input_tokens + output_tokens; self.calls += 1
    def allow_next(self, estimate):
        return self.used + estimate <= self.budget

t = UsageTracker(budget_tokens=6000)
for inp, out in [(1200, 300), (1500, 400), (1800, 500)]:
    t.record(inp, out)
print("used", t.used, "of", t.budget, "after", t.calls, "calls")
print("allow a 1000-token call?", t.allow_next(1000))
print("allow a 300-token call? ", t.allow_next(300))

```

Output:

```
used 5700 of 6000 after 3 calls
allow a 1000-token call? False
allow a 300-token call?  True
```

**Quiz:** Why record usage with feature and user labels?

- [ ] To make the model faster
- [x] To find which features and customers drive cost
- [ ] To avoid keys
- [ ] Because the API requires it

*Answer:* To find which features and customers drive cost. Attribution turns a single bill into actionable information.