Kimi K3 vs. Opus 5: Comparable Task Quality at 2x-4.6x Lower Cost
lqiao · x · 2026-07-28
Fireworks AI compared Kimi K3 and Opus 5 based on common business scenarios across SWE, algorithmic, and terminal tasks.
- Metrics: The key measurement is task-based cost rather than token-based cost, acknowledging that open models tend to be more verbose than closed ones.
- Quality and Cost: Across SWE (480), Algorithmic (100), and Terminal (83) tests, task-level quality is very close, with Opus 5 being on par or slightly better. However, under serverless pricing, K3's per-task cost is 2x to 4.6x cheaper.
- Future Goals: The team aims to continue increasing per-task serving efficiency via Fireworks Inference and improving quality via Fireworks Training.
Related event: Fireworks Test: Kimi K3 Matches Opus 5 Quality at Fraction of Cost(5 posts)→
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