Home / Rank #6

Output length control

Typical savings20–60% of output-token spend
EffortLow — prompt and max_tokens changes

Output tokens cost 3–8× more than input tokens (median ratio ~4:1). Verbose answers, unrequested explanations, and repeated boilerplate are billed at the premium rate. Tightening what the model is allowed to say is one of the cheapest wins available.

Structured outputs (JSON schemas), explicit length budgets in prompts, and hard max_tokens caps typically cut output spend 20–60% with zero quality loss for machine-consumed responses.

How to do it

  1. Set max_tokens deliberately per endpoint instead of leaving generous defaults.
  2. Use structured output / JSON mode for machine-consumed responses — schemas eliminate prose padding.
  3. Prompt for brevity explicitly ("answer in one sentence", "no preamble").
  4. Strip chain-of-thought from final outputs where reasoning does not need to be shown.

Frequently asked questions

Why do output tokens cost more?

Generation is sequential — each output token requires a full forward pass — while input tokens are processed in parallel. Providers price that compute asymmetry directly into the per-token rates.

Next method: #7 Context hygiene & token management