Claude Opus 5.5 vs Laguna S 2.1: Specs & Benchmark Comparison
Claude Opus 5.5 is developed by Anthropic, while Laguna S 2.1 comes from Poolside. Laguna S 2.1 was released in July 2026, and Claude Opus 5.5 followed 2 months later in September 2026. Laguna S 2.1 has a published size of about 118 billion parameters; Anthropic has not disclosed the parameter count of Claude Opus 5.5.
The two models share 3 published benchmarks. Claude Opus 5.5 leads on 3 of them. The widest gaps are on DeepSWE 1.1, where Claude Opus 5.5 scores 74.2% against 40.4%; SWE-Bench Pro, where Claude Opus 5.5 scores 89.9% against 59.4%. Averaged across everything we track, Claude Opus 5.5 sits at 71.1% and Laguna S 2.1 at 57.4%.
Laguna S 2.1 is the cheaper API at $0.10 per million input tokens and $0.20 per million output tokens, roughly 40 times cheaper than Claude Opus 5.5 at $4 and $20. Both accept a context window of about 1M tokens. Claude Opus 5.5 accepts text and images as input, while Laguna S 2.1 accepts text. On tooling, only Claude Opus 5.5 supports function calling and only Claude Opus 5.5 offers structured output.
| Characteristic | Claude Opus 5.5 | Laguna S 2.1 |
|---|---|---|
| Company | Anthropic | Poolside |
| Release Date | September 22, 2026 | July 21, 2026 |
| Parameters | — | 118B |
| Multimodal | Yes | No |
| Context (input) | 1.0M | 1.0M |
| Context (output) | 128K | — |
| Input Price / 1M | $4.00 | $0.10 |
| Output Price / 1M | $20.00 | $0.20 |
| Average Score | 71.1% | 57.4% |
| Benchmarks | ||
| DeepSWE 1.1 | 74.2% | 40.4% |
| SWE-Bench Pro | 89.9% | 59.4% |
| SWE-bench Multilingual | 93.9% | 78.5% |
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, Laguna S 2.1 — 0.6.
Laguna S 2.1 is 80.0x cheaper: input $0.10/1M vs $4.00/1M tokens.
Same context size: 1M tokens.
Claude Opus 5.5 is newer: released 9/22/2026 vs 7/21/2026.
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Frequently Asked Questions
Which is better for coding — Claude Opus 5.5 or Laguna S 2.1?
Which model is cheaper — Claude Opus 5.5 or Laguna S 2.1?
Which has a larger context window — Claude Opus 5.5 or Laguna S 2.1?
The Claude Opus 5.5 and Laguna S 2.1 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 Laguna S 2.1 page. See also the complete list of AI model comparisons.