What does a Kimi-K3 piano arrangement cost?
The question
Section titled “The question”The Director allowed one paid use of OpenRouter: piano arrangements for ai-jam-sessions, by Kimi-K3 only, with the cost estimated first and recorded after. What does one cost, and how close is offrig’s pre-spend budget?
What we found
Section titled “What we found”| arrangement | tokens in | tokens out | cost (OpenRouter’s figure) | wall time |
|---|---|---|---|---|
| Amazing Grace | 1,728 | 19,510 | $0.297834 | 196 s |
| America the Beautiful | 1,956 | 67,147 | $1.013073 | 528 s |
- Output dominates the cost. Kimi-K3’s output costs $13–15 per million tokens, against $0.67–0.72 for input, depending on the OpenRouter provider (read from OpenRouter’s public listing, 2026-10-08).
- offrig budgets the worst case: 200,000 output tokens at the most expensive provider’s rate, about $3.00 per call. For these two arrangements that’s 3–10× the actual spend. That’s deliberate: the budget is a ceiling checked before spending, not a forecast.
Caveats
Section titled “Caveats”- Two arrangements. Arrangement length varies a lot (19.5k vs 67k output tokens).
- Provider prices change. The per-provider split was read once and isn’t committed; offrig’s design doc records only the ranges.
Receipts
Section titled “Receipts”mcp-tool-shop-org/ai-jam-sessions:src/vocal/arrangements/source/amazing-grace-kimi-k3/meta.json(eeebfaa);.../america-the-beautiful-kimi-k3/meta.json(3661438);- produced by
scripts/arrange-hymn.ts.
mcp-tool-shop-org/offrig06aa1e3:docs/sidecar-design.md, section “The OpenRouter lane”.