Claude Opus 5.5 vs Kimi K3: Specs & Benchmark Comparison
Claude Opus 5.5 is developed by Anthropic, while Kimi K3 comes from Moonshot AI. Kimi K3 was released in July 2026, and Claude Opus 5.5 followed 2 months later in September 2026. Kimi K3 has a published size of about 2.8 trillion parameters; Anthropic has not disclosed the parameter count of Claude Opus 5.5.
The two models share 4 published benchmarks. Claude Opus 5.5 leads on 4 of them. The widest gaps are on Program Bench, where Claude Opus 5.5 scores 91.2% against 77.8%; AutomationBench, where Claude Opus 5.5 scores 40.0% against 30.8%. Averaged across everything we track, Claude Opus 5.5 sits at 71.1% and Kimi K3 at 67.8%.
Kimi K3 is the cheaper API at $3 per million input tokens and $15 per million output tokens, about 33% below Claude Opus 5.5 at $4 and $20. Both accept a context window of about 1M tokens. Both accept text and images as input.
| Characteristic | Claude Opus 5.5 | Kimi K3 |
|---|---|---|
| Company | Anthropic | Moonshot AI |
| Release Date | September 22, 2026 | July 16, 2026 |
| Parameters | — | 2.8T |
| Multimodal | Yes | Yes |
| Context (input) | 1.0M | 1.0M |
| Context (output) | 128K | 1.0M |
| Input Price / 1M | $4.00 | $3.00 |
| Output Price / 1M | $20.00 | $15.00 |
| Average Score | 71.1% | 67.8% |
| Benchmarks | ||
| Program Bench | 91.2% | 77.8% |
| AutomationBench | 40.0% | 30.8% |
| DeepSWE 1.1 | 74.2% | 69.0% |
| OfficeQA Pro | 67.7% | 63.3% |
Visual Benchmark Comparison
Verdict
Both models show equal results — the choice depends on your specific use case.
Both models show comparable average scores: Claude Opus 5.5 — 0.7, Kimi K3 — 0.7.
Kimi K3 is 1.3x cheaper: input $3.00/1M vs $4.00/1M tokens.
Same context size: 1M tokens.
Claude Opus 5.5 is newer: released 9/22/2026 vs 7/16/2026.
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Frequently Asked Questions
Which is better for coding — Claude Opus 5.5 or Kimi K3?
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Which has a larger context window — Claude Opus 5.5 or Kimi K3?
The Claude Opus 5.5 and Kimi K3 comparison is updated for 2026. Data includes benchmark results, API pricing, context window size and other specifications. For more detailed information, visit the Claude Opus 5.5 or Kimi K3 page. See also the complete list of AI model comparisons.