Claude Opus 5.5 vs Kimi K3.1 Pro
| Spec | Claude Opus 5.5 | Kimi K3.1 Pro |
|---|---|---|
| Respan Index | 74.1 (#1) | 71.1 (#4) |
| Blended price per 1M | $4 | $3.6 |
| Context window | 1M | 1.0M |
| Input / output per 1M | $2 / $10 | $1.8 / $9 |
| Max output | 128K | 1.0M |
| Input | text, vision | text, vision, video |
| Released | 2026-09-22 | 2026-10-23 |
Respan Index by category
Each category is scored 0 to 100, and how far ahead the winner is. Leads under a point are close to even.
| Category | Claude Opus 5.5 | Kimi K3.1 Pro |
|---|---|---|
| Coding | 68.3 Claude Opus 5.5 | 67.8 Kimi K3.1 Pro |
| Agents | 79.1 Claude Opus 5.5 | 69.3 Kimi K3.1 Pro |
| Reasoning | 83.9 Claude Opus 5.5 | 83.6* Kimi K3.1 Pro |
| Knowledge & language | 70.4 Claude Opus 5.5 | 71.2* Kimi K3.1 Pro |
| Human preference | 61.4 Claude Opus 5.5 | 58.5 Kimi K3.1 Pro |
* Estimated: no published scores in that category. How the Respan Index works
Benchmarks both report
Claude Opus 5.5 leads on 4 of the 4 benchmarks both report. Higher is better. Each score links to where it was published.
| Benchmark | Claude Opus 5.5 | Kimi K3.1 Pro |
|---|---|---|
| LMArena Agent (LMArena) | 0.2094 | 0.0596 |
| LMArena WebDev (LMArena) | 1810 | 1695 |
| Terminal-Bench 4.0 (Vals AI) | 65.2% | 63.6% |
| Terminal-Bench 4.0 | 66.4% | 65.7% |
FAQ
Is Claude Opus 5.5 better than Kimi K3.1 Pro?
Claude Opus 5.5 scores 74.1 on the Respan Index (#1), ahead of Kimi K3.1 Pro at 71.1 (#4). Claude Opus 5.5 leads on 4 of the 4 benchmarks both report.
Which is cheaper, Claude Opus 5.5 or Kimi K3.1 Pro?
Claude Opus 5.5 lists at $2 input and $10 output per 1M tokens; Kimi K3.1 Pro at $1.8 and $9. Kimi K3.1 Pro is 1.1x cheaper per token at list price.
Which has the larger context window?
Claude Opus 5.5 accepts 1M tokens and Kimi K3.1 Pro 1.0M tokens.