Step 1: baseline from real traffic

Log tokens per request, per feature, for at least a full usage cycle. Averages can hide expensive requests. Inspect the distribution for large contexts, long outputs, and repeated calls.

Step 2: budget per feature, not per account

  • Assign each AI feature its own monthly token budget derived from expected volume × measured per-request cost.
  • Tag requests by feature so overruns point at a culprit, not a mystery.
  • Give experimental features small, explicit budgets — experiments are where runaway spend hides.

Step 3: alerts before caps

  • Alert at 50% and 80% of budget — early enough to investigate, not just to panic.
  • Alert on anomalies too: sudden per-request cost spikes signal prompt or traffic changes.
  • Caps are the last resort: decide in advance which features degrade gracefully (shorter outputs, cheaper fallback) versus hard-stop.

Step 4: monthly review

Each month, compare budget to actuals per feature, investigate the top overruns, and re-baseline after any prompt, model, or traffic change. Budgets built on last quarter's prompts are fiction.

Assumptions and limits

  • Process guidance; specific tooling varies by provider.
  • No cost figures quoted.

Common questions

How much should I budget for AI API costs?

There is no universal number — it depends on your request volume, prompt sizes, and model choice. Budget from your own measured per-request cost times expected volume, plus a buffer for retries and growth. Anyone quoting you a flat figure without your numbers is guessing.

Should I set hard spending caps on AI APIs?

Caps can limit usage but may interrupt features. Choose alerts, graceful degradation, or hard limits according to the effect an interruption would have on your users.

Why did my AI bill spike suddenly?

The usual causes: a prompt change that lengthened inputs, a traffic spike, retries looping on failures, or a new feature shipping without a budget. Per-feature tagging and anomaly alerts turn 'mystery spike' into a five-minute diagnosis.

Last reviewed: . Developer guides for estimating AI API costs. Provider pricing changes often — always verify current rates with the provider.