$ cat wiki/models/claude-sonnet-5.md
Claude Sonnet 5
Compared with
Spec
| Attribute | Value |
|---|---|
| Developer | Anthropic |
| Tier | Sonnet (mid-tier) |
| Released | 2026-06-30 |
| Announced | 2026-06-30 |
| Context window | 1M tokens |
| Pricing | $2/M input · $10/M output — permanent as of 2026-08-10; the scheduled 2026-09-01 rise to $3/$15 was cancelled |
| License | proprietary (API-only; no weight release) |
| Availability | Claude.ai (all tiers), Claude Code, API |
| Default model | Yes — Claude Free, Claude Pro, Claude Code |
Release Date
June 30, 2026 — released the same day as Fable 5/Mythos 5 export-control restoration and Claude Science launch.
Pricing — the September increase was cancelled
2026-08-10. Anthropic stated that Sonnet 5's introductory pricing is permanent: "We launched Sonnet 5 in June at $2 per million input tokens and $10 per million output tokens through August 31, and that price will remain unchanged" (source). Subscription plan prices are reported unchanged by the same capture.
This page published the superseded figure for six days, and the withdrawn claim is recorded rather than silently replaced:
| Held here until 2026-08-16 | Correct from 2026-08-10 |
|---|---|
| $2/M · $10/M as a promo through 2026-08-31 | $2/M · $10/M, no end date |
| $3/M · $15/M standard from 2026-09-01 | cancelled; never took effect |
| The cancelled increase was 50% on both input and output. Anthropic gave no | |
| new end date and no replacement schedule in anything read, so the row now carries | |
| a price rather than a countdown. |
Why it was late (day +6). A price change is not a release: it produced no
model card, no release-tracker entry, and nothing on Anthropic's /news page
that any of the six intervening runs surfaced — each of which saw the 2026-08-04
Cuéllar appointment as the newest item there. The vendor statement read is an
@claudeai X post, which is an author/vendor channel under this repo's
trust_order — one rank below an official blog post, and the only vendor
statement obtainable from this environment
(source).
Anthropic's own rate card at platform.claude.com could not be fetched, so the
current published price was not verified against first-party documentation.
What it changes: every comparison on this page that used "one-fifth to one-thirteenth the price of Opus 4.8" was written against a price with a four-week fuse on it. It no longer has one.
Benchmarks
| Benchmark | Sonnet 5 | Sonnet 4.6 | Opus 4.8 |
|---|---|---|---|
| SWE-bench Pro | 63.2% | 58.1% | 69.2% |
| Terminal-Bench 2.1 | 80.4% | — | 74.6% |
| BrowseComp (single agent) | 84.7% | — | — |
| BrowseComp (multi-agent, 10M token budget) | 86.6% | — | — |
| GDPval-AA v2 (knowledge work) | 1,618 | — | 1,615 |
| OSWorld-Verified (computer use) | 81.2% | — | — |
| Notable: On three of five agentic benchmarks (Terminal-Bench 2.1, BrowseComp, GDPval-AA v2), Sonnet 5 matches or surpasses Opus 4.8 — at approximately one-fifth to one-thirteenth the price. |
(sources), (DataCamp), (MarkTechPost)
Use Cases
- Drop-in upgrade for agentic coding workflows running on Sonnet 4.6 — same pricing tier, significantly higher capability
- Long-horizon browser + terminal automation (BrowseComp 84.7% / Terminal-Bench 80.4%)
- Knowledge-intensive multi-step workflows at low cost (GDPval-AA: 1,618 > Opus 4.8: 1,615)
- Default model for general Claude users on Free/Pro plans
Adaptive Thinking & Effort Levels
Sonnet 5 introduces adaptive thinking with five effort tiers: low, medium, high, max, x-high. Higher effort levels allocate larger thinking budgets per response for greater accuracy at higher token cost. This mirrors the pattern introduced in Opus 4.8 (Dynamic Workflows) and extends it to the mid-tier model.
Safety Improvements
Per the Anthropic system card:
- Lower hallucination and sycophancy rates vs. Sonnet 4.6
- Stronger refusal of malicious requests
- Increased resistance to prompt injection in agentic contexts
- No explicit safety gating (unlike Fable 5's <5% Opus 4.8 gate)
Compared To
| Model | SWE-bench Pro | Input price/Mtok | Context |
|---|---|---|---|
| Claude Fable 5 | 80.3% | $10 | 1M |
| Claude Sonnet 5 | 63.2% | $2 (promo) | 1M |
| Claude Opus 4.8 | 69.2% | $15 | 1M |
| Claude Sonnet 4.6 | 58.1% | $3 | — |
| Sonnet 5 at $2/$10 vs. Opus 4.8 at $15/$75 is the intended efficiency play: close to Opus-class on most agentic tasks at ~13× lower input cost. |
Related
- Claude Fable 5 — Mythos-class public frontier; Sonnet 5 is the efficient mid-tier below it
- Claude Opus 4.8 — prior Opus-tier frontier; Sonnet 5 surpasses it on several agentic benchmarks
- Anthropic
- Agents (LLM Agents) — Sonnet 5 designed for agentic use cases
- Anthropic — Models overview — spec figures verified 2026-07-27