Claude Sonnet 5 is the first model to test before paying Claude Opus API prices for routine coding and agent work. Anthropic launched it on June 30, 2026 with the API model ID claude-sonnet-5, a 1M-token context window, up to 128K output tokens, and introductory API pricing of $2 input / $10 output per 1M tokens through August 31, 2026. Standard pricing becomes $3 / $15 on September 1.
Anthropic says Sonnet 5 is “close to” Opus 4.8 and can match it on some tasks at higher effort. That is vendor positioning, not an independent general ranking. Keep Opus 4.8 for the highest-accuracy review, architecture, and final-arbitration work until your own task results justify moving that boundary.
Low-cost supported-tool/API lane
GLM-5.2
$1.40 in / $4.40 out
1M context
Vendor specs + independent Artificial Analysis signal
Claude cost/performance test
Sonnet 5
$2 / $10 through Aug 31
$3 / $15 after · 1M context
Anthropic vendor evidence; independent normalized result pending
Premium accuracy and arbitration lane
Opus 4.8
$5 in / $25 out
1M context
Vendor specs + independent Artificial Analysis signal
USD per 1 million tokens. Prices, context limits, and evidence provenance are separate decision inputs; this is not a benchmark ranking.
Quick facts
| Spec | Claude Sonnet 5 |
|---|---|
| Launch date | June 30, 2026 |
| API model ID | claude-sonnet-5 |
| Context window | 1M tokens |
| Maximum output | 128K tokens |
| Thinking | Adaptive thinking on by default; control depth with effort |
| Introductory API price | $2 input / $10 output per 1M through August 31, 2026 |
| Standard API price | $3 input / $15 output per 1M from September 1, 2026 |
| Best first use | Coding agents, tool use, knowledge work, and routine Claude production |
| Evidence boundary | Launch comparisons are Anthropic-reported; independent normalized results are pending |
The tokenizer changes the real cost
Sonnet 5 uses a new tokenizer. Anthropic’s migration guide says the same text produces approximately 30% more tokens than Sonnet 4.6; the launch footnote gives a content-dependent range of roughly 1.0–1.35×. That means the 1M-token window holds less equivalent text, a prior max_tokens value may truncate an equivalent response, and per-request cost can rise even when the listed per-token rate is unchanged.
The introductory $2/$10 rate is intended to make migration roughly cost-neutral. Do not assume it makes every workload cheaper. Re-run token counting and measure complete agent loops—including thinking, tool results, retries, and output—before changing production budgets.
API migration checklist
Sonnet 5 is close to a drop-in upgrade from Sonnet 4.6, but two changes can return HTTP 400 errors:
- Replace manual extended thinking (
thinking: {type: "enabled", budget_tokens: N}) with adaptive thinking and theeffortparameter. Adaptive thinking is on by default; explicitly disable it when needed. - Remove non-default
temperature,top_p, andtop_kvalues.
Also update the model ID, re-count tokens, review max_tokens, and handle cybersecurity refusals returned as HTTP 200 responses with stop_reason: "refusal". Priority Tier is not available for Sonnet 5 at launch.
Where it is available
| Surface | Launch status | Primary evidence |
|---|---|---|
| Claude.ai | Default for Free and Pro; available to Max, Team, and Enterprise | Anthropic launch |
| Claude Code | Available at launch | Anthropic launch |
| Claude API | Available to all customers as claude-sonnet-5 | Anthropic platform docs |
| GitHub Copilot | Generally available from June 30 | GitHub changelog |
| AWS | Amazon Bedrock and Claude Platform on AWS | AWS launch post |
AWS notes that regional availability varies. Anthropic’s platform documentation also distinguishes the current Claude-in-Bedrock Messages endpoint from legacy Bedrock InvokeModel and Converse paths, so verify the exact integration rather than assuming every older endpoint supports Sonnet 5.
How to read the launch benchmarks
Treat every launch comparison as vendor evidence. Anthropic says Sonnet 5 substantially improves over Sonnet 4.6 in reasoning, coding, tool use, and knowledge work, and that higher-effort Sonnet 5 can match Opus 4.8 on some tasks. Those claims justify a test, not a universal replacement decision.
Anthropic also corrected the BrowseComp cost-performance chart on launch day because the original used a simpler methodology than its standard agentic-search evaluation. Prefer the updated launch chart and Sonnet 5 system card over copied launch-day numbers. Do not combine BrowseComp, OSWorld-Verified, SWE-bench, or unrelated independent indexes into one synthetic score.
Buying decision
- Start with Sonnet 5 when you want Claude quality without defaulting to Opus pricing.
- Keep GLM-5.2 as the lower-cost supported-tool/API lane when its tool restrictions and quota mechanics fit.
- Use Opus 4.8 when a premium second pass changes architecture, correctness, or risk decisions.
- Compare subscription seats separately from API tokens in the Smart Spend guide.
Related links
- /value/smart-spend/
- /models/glm-5.2/
- /models/claude-opus-4-8/
- /compare/models/mid-range/
- /compare/models/premium/
Sources
- Anthropic: Introducing Claude Sonnet 5 (Archive)
- Anthropic Platform: What’s new in Claude Sonnet 5 (Archive)
- Anthropic Platform: Migration guide (Archive)
- Anthropic: Claude Sonnet 5 system card
- GitHub: Claude Sonnet 5 is generally available for GitHub Copilot (Archive)
- AWS: Introducing Claude Sonnet 5 on AWS (Archive)
Last verified: July 1, 2026. Introductory pricing ends August 31, 2026; availability, limits, and independent evidence can change sooner.