Claude Opus 5.5 vs Claude Sonnet 5.
Verdict by category, tale of the tape, shared benchmarks only, and cost at three workloads — all from the tracked data.
Verdict by category
| Category | Claude Opus 5.5 | Claude Sonnet 5 | Winner |
|---|---|---|---|
| League Score | 96.4 | 73.9 | Claude Opus 5.5 |
| Coding (SWE-bench %) | — | 85.2 | — |
| Reasoning (GPQA %) | — | — | — |
| Context (tokens) | 1000000 | 1000000 | Draw |
| Speed (tok/s) | 75.6 | — | — |
| Price (blended $/1M) | $8.00 | $4.00 | Claude Sonnet 5 (cheaper) |
Tale of the tape
| Spec | Claude Opus 5.5 | Claude Sonnet 5 |
|---|---|---|
| Maker | Anthropic | Anthropic |
| Released | Sep 22, 2026 | Jun 30, 2026 |
| League Score | 96 | 74 |
| Context | 1,000,000 tokens | 1,000,000 tokens |
| Max output | 128,000 | 128,000 |
| $/1M input | $4.00 | $2.00 |
| $/1M output | $20.00 | $10.00 |
| Weights | Closed | Closed |
| Speed | 75.6 t/s | — |
Head-to-head benchmarks (shared only)
| Benchmark | Claude Opus 5.5 | Claude Sonnet 5 |
|---|---|---|
| LiveBench overall | 86.5 | 74.6 |
Cost at three workloads
| Workload | Claude Opus 5.5 | Claude Sonnet 5 |
|---|---|---|
| Light — 1M in / 250K out | $9.00 | $4.50 |
| Standard — 10M in / 2.5M out | $90.00 | $45.00 |
| Long-context — 50M in / 5M out | $300.00 | $150.00 |
The pick
Pick Claude Opus 5.5 if you want the higher overall League Score.
Pick Claude Sonnet 5 if you want the lower running cost; coding is the priority.
All figures from the model database — sources and dates on each model page. Cost your own workload or compare a different pair.
Frequently asked questions
Which is better overall, Claude Opus 5.5 or Claude Sonnet 5?
Claude Opus 5.5 leads on overall League Score, 96 to 74 — a gap of 22 points on a composite of sourced benchmarks. That is overall form, not every category: check the per-category verdicts before choosing.
Which is cheaper, Claude Opus 5.5 or Claude Sonnet 5?
Claude Sonnet 5 is cheaper: $4.00 vs $8.00 blended per 1M tokens (3:1 input/output mix) — about 2.0x less per token.
Which has the bigger context window, Claude Opus 5.5 or Claude Sonnet 5?
Neither — both take 1M of context.
Are Claude Opus 5.5 and Claude Sonnet 5 open source?
Claude Opus 5.5 is closed weights — API access only; Claude Sonnet 5 is closed weights — API access only.