Kimi K3.1 Pro vs Claude Opus 5.5
Kimi K3.1 Pro and Claude Opus 5.5 are within three points on the Models at Work leaderboard, which we treat as a tie (86 vs 85). Kimi K3.1 Pro is about 2.0× cheaper per blended million tokens ($4 vs $8). On Artificial Analysis' independent Intelligence Index, Claude Opus 5.5 leads 58 to 55.
| Kimi K3.1 Pro · Moonshot | Claude Opus 5.5 · Anthropic | |
|---|---|---|
| Leaderboard rank | #2 | #3 |
| Score (0–100) | 86 | 85 |
| Tier | Open weights | Frontier |
| Price per 1M tokens | $2 in · $10 out | $4 in · $20 out |
| Context window | 1M | 1M |
| Open weights | Yes | No |
| Artificial Analysis Intelligence Index | 55 | 58 |
| Terminal-Bench 4.0 (vendor) | 65.7% | — |
| Arena text score | — | 1507 |
| Humanity's Last Exam, Diamond (Scale) | — | 55.0 |
| Epoch Capabilities Index | — | 167 |
| Best for | Agentic coding with an open-weight exit, 1M-token long-context work, Moving off Kimi K3 | Agentic coding, Long-running agents, Enterprise knowledge work |
Compare source-qualified API rates and a monthly workload example before estimating your bill.
Choose Kimi K3.1 Pro if…
- you need agentic coding with an open-weight exit
- you need 1m-token long-context work
- you need moving off kimi k3
Fourth on the Artificial Analysis index at 55, one point behind Sonnet 5.5, at the same $2 in / $10 out list price, with the weights still to come.
Caveats: Scores within three points of Sonnet 5.5 (tie), and ranks on evals and price alone because no practitioner sentiment exists yet. Moonshot says the full weights arrive by 4 Nov 2026; until then it is open-weight in intent, hosted-only in practice. Artificial Analysis rates it slow (51 tokens/s) and very verbose: 150M tokens to run its index, which is where the $2.11 per-task cost comes from. Moonshot's Terminal-Bench figure is vendor-run and is not counted. No Arena or Scale result yet, and no practitioner threads in Signals, so sentiment is left out.
Choose Claude Opus 5.5 if…
- you need agentic coding
- you need long-running agents
- you need enterprise knowledge work
The model people actually ship agents on: top of the independent index, a price that does not need a budget meeting, and a community that complains mainly about how much it has to be used.
Caveats: Arena puts Gemini 4 Argon ahead on chat preference; the gap is inside two scores' error bars.
What practitioners say
Kimi K3.1 Pro: No practitioner threads recorded in Signals yet; left out of the score rather than guessed.
Claude Opus 5.5: The launch thread was the biggest Claude thread of the year on Hacker News, a port of the TypeScript compiler to Rust credited the model with a working build in ten hours, and a Vals AI materials-discovery run used it for agentic simulation. A 'has it been nerfed yet' tracker is the most-upvoted scepticism.
Questions people ask
Which is better, Kimi K3.1 Pro or Claude Opus 5.5?
Kimi K3.1 Pro and Claude Opus 5.5 are within three points on the Models at Work leaderboard, which we treat as a tie (86 vs 85). Kimi K3.1 Pro is about 2.0× cheaper per blended million tokens ($4 vs $8). On Artificial Analysis' independent Intelligence Index, Claude Opus 5.5 leads 58 to 55.
When should I choose Kimi K3.1 Pro over Claude Opus 5.5?
Choose Kimi K3.1 Pro for agentic coding with an open-weight exit, 1m-token long-context work, moving off kimi k3. Fourth on the Artificial Analysis index at 55, one point behind Sonnet 5.5, at the same $2 in / $10 out list price, with the weights still to come.
When should I choose Claude Opus 5.5 over Kimi K3.1 Pro?
Choose Claude Opus 5.5 for agentic coding, long-running agents, enterprise knowledge work. The model people actually ship agents on: top of the independent index, a price that does not need a budget meeting, and a community that complains mainly about how much it has to be used.
Which is cheaper, Kimi K3.1 Pro or Claude Opus 5.5?
Kimi K3.1 Pro costs $2 per million input tokens and $10 per million output tokens on Moonshot's list price (Kimi API model pricing, read Oct 26, 2026). Claude Opus 5.5 costs $4 per million input tokens and $20 per million output tokens on Anthropic's list price (Claude pricing, read Oct 26, 2026).
Scores come from the Models at Work leaderboard: Score is 0 to 100 and computed, not typed: 55% independent evals (Artificial Analysis, Arena, Scale SEAL, Epoch, each scaled against its natural floor and the best score in this table, then averaged), 15% blended price on a fixed log scale ($0.05 per million is 100, $60 is 0), 15% practitioner sentiment from Signals and community threads, 15% operational fit (context window, open weights). A missing component drops out and the rest are reweighted. A model with no independent eval yet is provisional and ranks below every measured one. Within three points is a tie. Vendor-published figures are labelled and never counted. Prices are vendor list prices where published; blended figures assume three input tokens per output token.