Best starting models for Classification / extraction, priced per call.

A document goes in, a label or a small JSON object comes out. Moderation, routing, tagging, field extraction. The output is a rounding error.

With output negligible, the input rate times volume is the whole bill, so tier choice is the only lever that moves it. Small models are purpose-built for this.

  • Input rate times volume is the entire bill.
  • Output is a rounding error.
  • Tier choice is the only lever that moves it.

The pipeline

A feature is a chain of calls, each with a different job. Steps run top to bottom.

  1. 01

    classify / extract

    label the document or pull structured fields to JSON

    Small cost-driver step
    per-call shape 300 sys + 800 in + 5 out
    cheap default GPT-4.1 Nano ≈ $0.0001 per call
    step-up for quality Claude Haiku 4.5 ≈ $0.0011 per call
    open-weight option Mistral Small 4 ≈ $0.0001 per call
    See all small-tier models in the price table

How to choose for Classification / extraction

One step, classify / extract, runs at volume: a document in, a label or small JSON object out. There is no capable-model step. Output is a rounding error, so the input rate times your volume is effectively the entire bill.

Tier choice is the only lever that moves it, and small models are purpose-built for this, so start small and let an eval tell you whether you can keep it. Watch cost per accepted result, not cost per call: a cheap model that mislabels and forces a human review is not cheap. These jobs rarely care about latency, so batch pricing often stacks on top.

The takeaway

No step here needs a frontier model. The bill concentrates on the cost-driver step (classify / extract); a small model handles it.

No fabricated bills, no rankings.