Claude Opus 5 vs Sonnet 5: Benchmarks, Pricing & Which to Use (July 2026)

Last updated: July 25, 2026

Anthropic now has two strong mid-to-premium Claude models: Claude Opus 5 (released July 24, 2026) and Claude Sonnet 5 (released June 30, 2026). Both share the same 1M-token context window and 128K max output. Both support adaptive thinking. Both are available in Claude Code, the API, and across Claude plans. The question is no longer “which one is better” — it is “which one is better for your workload.”

Quick answer: Opus 5 ($5/$25 per MTok) is the premium model — SOTA on Frontier-Bench, 3x next-best on ARC-AGI 3, and within 0.5% of Fable 5 on CursorBench at half the cost. Sonnet 5 ($3/$15, intro $2/$10 through August 31) handles everyday coding, research, and professional work at a lower price. Opus 5 has a May 2026 knowledge cutoff; Sonnet 5’s is January 2026. Start with Sonnet 5 for cost-sensitive work; use Opus 5 when accuracy on complex, multi-step tasks justifies the premium.

What each model is

Claude Opus 5 is Anthropic’s newest Opus-class model — the everyday premium tier. It delivers near-Fable 5 intelligence at half the price, with the freshest knowledge cutoff of any Claude model (May 2026). On Frontier-Bench v0.1 it more than doubles Opus 4.8’s score and surpasses all other models. On CursorBench 3.2 it performs within 0.5% of Fable 5’s peak. It is the default model on Claude Max and the strongest model on Claude Pro.

Claude Sonnet 5 is Anthropic’s newest Sonnet-class model — the workhorse tier. Released June 30, 2026, it is designed for agentic work: coding, tool use, browser automation, research, and professional-task completion. It is the default model on Claude Free and Pro, and its introductory pricing ($2/$10 per MTok through August 31) makes it the most cost-effective entry point into the Claude 5 generation.

The positioning is straightforward: Sonnet 5 is the model you test first; Opus 5 is the model you escalate to when accuracy on hard tasks justifies the premium.

Benchmark comparison

Benchmark data for these two models comes from different sources — Anthropic’s Opus 5 launch materials emphasize Frontier-Bench, ARC-AGI 3, and OSWorld 2.0, while the Sonnet 5 System Card reports SWE-bench, Terminal-Bench, and BrowseComp. Where both models report the same benchmark, the comparison is direct. Where they do not, treat the data as directional.

Coding and software engineering

Three observations:

1. Opus 5’s headline benchmarks are different from Sonnet 5’s. Opus 5’s launch emphasizes Frontier-Bench (where it is SOTA) and CursorBench (where it nearly matches Fable 5). Sonnet 5’s System Card reports SWE-bench and Terminal-Bench. The lack of overlapping benchmarks makes a direct coding comparison imprecise.
2. Where Sonnet 5 reports scores, they are strong but below Fable 5 and Opus 4.8 on the hardest tests. Sonnet 5’s 63.2% on SWE-bench Pro trails Opus 4.8’s 69.2% and Fable 5’s 80.3%. Opus 5 does not report SWE-bench Pro individually, but its Frontier-Bench and CursorBench results suggest it is at or above Opus 4.8 level.
3. Both are major upgrades over their predecessors. Opus 5 more than doubles Opus 4.8 on Frontier-Bench. Sonnet 5 more than doubles Sonnet 4.6 on FrontierCode (38.8% vs 15.1%).

Reasoning, agents, and knowledge work

Opus 5 dominates on reasoning-heavy and agentic benchmarks. Sonnet 5 holds its own on tool-assisted tasks (BrowseComp, HLE with tools) and computer use (81.2% on OSWorld-Verified), but the gap widens on novel reasoning (ARC-AGI 3) and professional knowledge work (GDPval-AA).

Science and specialized domains

Opus 5 outperforms Opus 4.8 on every life sciences evaluation, including +10.2 points on organic chemistry and +7.7 points on protein function prediction. It is now Anthropic’s most capable generally available model for scientific research, since Fable 5’s biology safeguards are more restrictive. Sonnet 5’s System Card does not emphasize scientific benchmarks.

Treat vendor-published benchmarks as directional. Validate on your own workload before committing budget.

Pricing comparison

Both models use per-million-token pricing. Sonnet 5 has temporary introductory pricing through August 31, 2026.

The price ratio is roughly 1.67x at standard pricing ($5/$3 input, $25/$15 output) and 2.5x during Sonnet 5’s introductory period ($5/$2 input, $25/$10 output).

Cost strategy:

• During intro pricing (through Aug 31): Sonnet 5 is exceptionally competitive. For high-volume work where near-Opus quality is sufficient, it is the clear default.
• After Aug 31: The 1.67x ratio means Opus 5 costs about 67% more per token. If Opus 5 completes tasks in fewer turns with fewer retries, the effective cost gap narrows.
• Prompt caching reduces costs for both models by up to 90% on repeated context. Cache hits are $0.50/MTok on Opus 5 and $0.30/MTok on Sonnet 5.
• Fast mode is Opus 5 only — approximately 2.5x speed at 2x base price ($10/$50 per MTok). Sonnet 5 does not have a fast mode.

Tokenizer caveat: Sonnet 5 uses an updated tokenizer. The same input can become roughly 1.0x to 1.35x as many tokens compared to Sonnet 4.6, depending on content type. Measure real prompts rather than estimating from old token counts.

Feature comparison

The four-month knowledge cutoff gap matters more than it looks. If your work involves recent libraries, APIs, regulations, or events from February–May 2026, Opus 5 has reliable knowledge that Sonnet 5 does not.

When to use Opus 5 vs Sonnet 5

The best metric is cost per successful task, not price per token. Opus 5’s efficiency gains — fewer retries, fewer tokens, less latency — mean it can be cheaper in practice than a lower-priced model that needs more iterations.

Use case breakdowns

Coding

Winner: Opus 5 for complex work; Sonnet 5 for everyday tasks.

Opus 5 is SOTA on Frontier-Bench v0.1 and within 0.5% of Fable 5 on CursorBench 3.2. Customers report it catches its own mistakes, verifies its work in a browser at desktop and mobile widths, and handles multi-file migrations that previous Opus models could not. It uses fewer tokens at higher effort levels — one customer reports 1/7 the reasoning tokens and half the latency of Opus 4.8.

Sonnet 5 scores 85.2% on SWE-bench Verified and 80.4% on Terminal-Bench 2.1 — strong results for everyday coding. It handles bug fixes, test generation, refactors, and CI triage well. But on the hardest long-horizon tasks (SWE-bench Pro: 63.2%), it trails Opus 4.8 (69.2%) and Fable 5 (80.3%).

Practical setup: Use Sonnet 5 as the default in Claude Code. Escalate to Opus 5 for complex debugging, multi-repo refactors, and tasks where Sonnet 5 fails or needs multiple retries. See Best AI Agents for Coding in 2026 for the broader landscape.

Agents

Winner: Opus 5 for production agents; Sonnet 5 for cost-sensitive agents.

Opus 5’s agentic benchmarks are dominant: 3x next-best on ARC-AGI 3, ~1.5x next-best on Zapier AutomationBench (with a 100% pass rate), and surpassing Fable 5 on OSWorld 2.0 at a third of the cost. Its self-verification behavior — checking assumptions, cross-checking results by independent methods — makes it more reliable for long-running, multi-step workflows.

Sonnet 5 is designed for agentic work and improves significantly over Sonnet 4.6 on tool use, browser automation, and business workflow tasks. Its 84.7% on BrowseComp and 57.4% on HLE with tools show strong tool-assisted reasoning. But it still shows higher rates of some misaligned behavior than Opus models in Anthropic’s internal evaluations.

Practical setup: Use Sonnet 5 as the first pass. If the task fails or confidence is low, route to Opus 5. A human reviews high-risk outputs before deployment.

Writing and content creation

Winner: Sonnet 5 for most writing; Opus 5 for analytical depth.

For drafting, editing, and producing content, Sonnet 5 is the better value. It handles blog posts, documentation, summaries, and creative writing at a lower cost. Opus 5 shines for long-form analytical writing, technical documentation that requires deep reasoning, and content where accuracy on recent topics matters (its May 2026 cutoff helps here).

Research

Winner: depends on the research type.

Sonnet 5’s BrowseComp (84.7%) and HLE with tools (57.4%) make it strong for web research, source discovery, and multi-source synthesis. Opus 5 leads on DeepSearchQA and HLE without tools, and its May 2026 knowledge cutoff means it has reliable knowledge of recent developments that Sonnet 5 lacks.

For scientific research specifically, Opus 5 is the clear choice — it is Anthropic’s most capable generally available model for science, with fewer biology restrictions than Fable 5.

Enterprise

Winner: Opus 5 for most enterprise workloads.

Both models support zero data retention, which is the key enterprise requirement. But Opus 5 adds stronger alignment (lowest deceptive behavior of any recent Claude model), better self-verification, a fresher knowledge cutoff, and fast mode for latency-sensitive applications. Sonnet 5 is the right choice for high-volume enterprise pipelines where cost per token dominates and the task complexity is moderate.

The competition angle

Both Opus 5 and Sonnet 5 compete with OpenAI’s GPT-5.6 family. The positioning:

Opus 5’s price-to-performance ratio is the story. At $5/$25 per MTok, it matches or approaches GPT-5.6 Sol ($5/$30 per MTok) on most benchmarks while including a full 1M-token context at its standard rate. GPT-5.6 Sol applies a 2x input surcharge above 272K tokens — Opus 5’s 1M context has no such surcharge.

Sonnet 5 at $3/$15 per MTok (intro $2/$10) undercuts GPT-5.6 Terra on price while matching or exceeding it on coding and agentic benchmarks. During the introductory period, Sonnet 5 is one of the most cost-effective frontier-class models available.

For the detailed head-to-head at the frontier tier, see GPT-5.6 Sol vs Claude Fable 5.

FAQ

The bottom line

Claude Opus 5 and Claude Sonnet 5 are not competitors — they are complements. Sonnet 5 is the default workhorse: strong coding, research, and professional work at the lowest cost in the Claude 5 generation. Opus 5 is the premium escalation: near-Fable 5 intelligence at half the price, with the freshest knowledge, strongest reasoning, and best alignment of any Claude model.

Start with Sonnet 5. Test it on your real workload. If it completes tasks reliably, you are getting excellent value — especially during introductory pricing through August 31. Escalate to Opus 5 when accuracy on complex tasks justifies the premium, when you need post-January 2026 knowledge, or when your work touches science, enterprise compliance, or high-stakes agentic workflows.

For the full model-by-model breakdowns, see the Claude Opus 5 guide and the Claude Sonnet 5 guide. For the previous-generation comparison, see Fable 5 vs Opus 4.8.