C
Claude Sonnet 5.5
Half the price of Opus and only 10% cheaper per task — the best-value general-purpose flagship
Intelligence v5
54.5
Leaderboard rank
#5
Input / output
$2.00/$10.00
Blended 3:1
$4.00
Output speed
135 tok/s
Value
14 pts/$
Capability profile Normalised to the field maximum
Specifications
Vendor
Anthropic
Released
2026-09
Weights
Closed, API only
Context
1,000,000 tokens
Max output
128,000 tokens
Parameters
Undisclosed
Input price
$2.00 / 1M
Output price
$10.00 / 1M
Cache hit
$0.10 / 1M
Output speed
135 tok/s
Intelligence
54.5（v5）
Benchmark scores
How it is measured →Ranked 5 · bars are scaled to the field maximum for that benchmark.
| Benchmarks | Score | Vs. best in field | Gap |
|---|---|---|---|
| AA Intelligence Index v5 Intelligence index | 54.5 | 91% | −5.5 pts |
| AA Intelligence Index v4.3.2 Intelligence index (legacy) | 56.0 | 97% | −1.6 pts |
| GPQA Diamond Graduate-level science reasoning | 95.6 | 99% | −0.8 pts |
| Terminal-Bench 4.0 Terminal-agent tasks | 63.6 | 95% | −3.6 pts |
| LiveBench Design Document generation (DOCX/PPT/PDF) | 85.0 | 98% | −1.9 pts |
| Vals Index Vals composite index | 73.1 | 100% |
Assessment
Opus 5.5 costs twice as much per million tokens, yet only about 10% more per completed task because it writes fewer tokens. Sonnet 5.5 beats Opus on three agent-style tests: Terminal-Bench 4.0 63.6/59.6, AutomationBench-AA 72/70, AA-Briefcase 1823/1807 Elo. Available on the free claude.ai tier.
At the same price
The four models closest on blended price, side by side.
| Model | v5 | Blended | tok/s | Score gap |
|---|---|---|---|---|
| GPT-6.1 SolOpenAI | 54.6 | $4.00 | 77 | +0.1 |
| Gemini 4 ArgonGoogle | 50.4 | $4.00 | 80 | -4.1 |
| Kimi K3.1 Pro Open weightsMoonshot AI | 46.0 | $4.00 | 28 | -8.5 |
| Grok 4.7xAI | 34.3 | $3.00 | 105 | -20.2 |
Compare side by side
Line it up against other models on price, speed and every benchmark.
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