Kimi K3 vs Claude Opus 5: same-tier frontier reasoning, very different price?
Kimi K3 is the value-frontier pick for same-tier reasoning. Pick Opus 5 only when Anthropic's tooling, safety tuning, or instruction-following edge cases are the deciding factor - and budget the 40% premium.
A frontier-tier reasoner from Moonshot AI priced like a workhorse.
Kimi K3 is Moonshot AI's frontier reasoning model and often lands in the same smartness tier as Claude Opus 5. The comparison tests whether a non-US frontier lab can deliver top-tier reasoning at meaningfully lower per-token cost - and on paper, it can.
By TechCompare · Updated
Cost Comparison
Based on 100,000 input tokens (50% cached), 5,000 output tokens, and 100 requests.Prices are fetched live from OpenRouter and may include temporary promotional discounts not accounted for in our article and comparison figures.
Side-by-side specs
| Spec | Kimi K3 | Claude Opus 5 |
|---|---|---|
| Input Cost (per M) | $3.00 (better on this spec) | $5.00 |
| Output Cost (per M) | $15.00 (better on this spec) | $25.00 |
| Cached Input (per M) | $0.30 (better on this spec) | $0.50 |
| Batch Discount | 0% | 50% (better on this spec) |
| Context Window | 1M | 1M |
How they differ
Kimi K3 is priced at $3.00 per million input tokens and $15.00 per million output tokens, with a 90% caching discount ($0.30 per million) and a 1M context window. Claude Opus 5 is priced at $5.00 per million input tokens and $25.00 per million output tokens, also with a 90% caching discount ($0.50 per million) and a 1M context window. For a typical 100K input + 10K output request, Kimi K3 costs $0.45 vs Opus 5's $0.75 - a 40% discount per call. Both are text-in / text-out with file input. K3 lacks Anthropic's mature tool ecosystem and Claude's refined instruction-following nuance, but for pure reasoning at the frontier tier, the per-token economics favor Kimi hard.
Verdict
Kimi K3 charges $3.00/M input and $15.00/M output against Opus 5's $5.00 and $25.00, about 40% cheaper on every base row. Cached input mirrors that at $0.30/M versus $0.50/M. The one row Opus wins is batch, where its 50% discount drops output to $12.50/M and overtakes Kimi's $15/M live price on async bulk work. Context ties at 1M. Reach for Opus 5 when its tool ecosystem and safety tuning earn the premium in ops cost.
Which should you pick?
Choose Kimi K3
High-volume frontier reasoning where per-token cost dominates. Kimi K3's 40% discount on input and output makes it the economical choice at scale.
Choose Claude Opus 5
Tasks that lean on Anthropic's specific instruction-following nuance, mature tool-calling API, or safety-policy tuning. The premium earns its keep when those features directly reduce ops cost.