When to Choose Each Option
Clear guidance based on your specific situation and needs.
Our Recommendation
Claude Sonnet 5 is the clear default for new work: a 1M-token context, 128K outputs, and near-Opus 4.8 agentic performance make it a real generational step over Sonnet 4. The nuance is cost — the Opus 4.7 tokenizer can inflate token counts by up to ~1.3x, so the intro $2/$10 pricing doesn't automatically mean cheaper bills than Sonnet 4. Choose Sonnet 5 for agentic coding, long context, and future-proofing; stick with Sonnet 4 only if you've tuned tightly to its tokenizer, run standard short tasks, or rely on creative/SVG work where Sonnet 5's early reviews were mixed. Update (September 29, 2026): Claude Sonnet 5.5 widens this gap further — 70.6% on Terminal-Bench 4.0 versus Sonnet 5's 10.3%, a GDPval-AA ELO of 1844 just two points under flagship Opus 5.5 (1846), and the first Sonnet to ship with Opus-class cyber safeguards. Pricing is unchanged at $2/$10 per million tokens, but the model runs 30%+ faster and typically costs up to 30% less per task — and Claude Code 2.1.284 has already made claude-sonnet-5-5 the default Sonnet.
- Choose Claude Sonnet 5 when...
- You want the current default with the strongest agentic coding and tool use in the Sonnet line.
- Your work needs the full 1M-token context or long 128K outputs.
- You're starting fresh and want intro pricing before the Aug 31, 2026 standard rates kick in.
- You're building long-horizon agents that benefit from near-Opus reasoning at Sonnet cost.
- You want near-flagship knowledge-work and agentic performance at Sonnet pricing — Sonnet 5.5 sits two GDPval-AA ELO points under Opus 5.5 at the same $2/$10 price as Sonnet 5.
- Choose Claude Sonnet 4 when...
- You have prompts tuned to Sonnet 4's tokenizer and want predictable token counts and cost.
- Your workloads are standard, short-context tasks where Sonnet 5's extras add no value.
- Creative or SVG work is core and Sonnet 5's early results were weaker for you.
- You need stability and don't want to re-validate a pipeline against a brand-new default.
- Your organization runs a pinned, validated Sonnet 4 pipeline where re-certification outweighs the benchmark gains of the 5.x line.