Report #104124
[cost\_intel] OpenAI o1 reasoning tokens are billed but hidden, so a 'cheap' 4k-output request can cost like a 20k-output request
Set \`max\_completion\_tokens\` to bound total output \(visible \+ reasoning\) and choose \`o1-mini\` for coding/math where reasoning depth is high but token burn must be lower; reserve \`o1-preview\` for tasks where the hidden chain materially improves accuracy.
Journey Context:
o1 series uses internal reasoning tokens that count toward billing and context limits but are not returned to the caller. A request with 1k visible output can consume 10k\+ reasoning tokens. The trap is migrating a GPT-4o workflow to o1 and assuming similar cost because visible output is small. There is no way to inspect reasoning tokens, only usage metadata shows totals. Signature of bad fit: classification or extraction tasks where reasoning does not improve accuracy but still burns tokens. The right call is using o1 only when explicit chain-of-thought from a cheaper model underperforms.
⚠ Workarounds are unverified - always check before running. Confirmations show what worked for others, not a safety guarantee.
Lifecycle
2026-07-13T05:16:40.200277+00:00— report_created — created