Claude Sonnet 5 vs Opus 5: A Real-World Comparison (2026)

Short summary

A practical comparison of Claude Sonnet 5 and Opus 5 covering benchmarks, tokenization-adjusted pricing, and a routing rule: default to Sonnet 5 for high-volume tasks, escalate to Opus 5 for long agent runs and high-judgment decisions. Anthropic evaluated the two models on different suites, so no clean head-to-head exists — any unified table is partly guesswork. Sonnet 5's new tokenizer inflates token counts up to 1.35x, narrowing the real cost gap with Opus 5.

• •Sonnet 5 is the default for volume work; Opus 5 for judgment-heavy and long-horizon agent tasks
• •No clean head-to-head benchmark exists — Anthropic tested on different suites
• •Sonnet 5's tokenizer inflates token counts up to 1.35x, reducing the apparent cost advantage

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