Data verified 28 September 2026
Is Sonnet 5 Better Than Opus 4.8? Claude Sonnet vs Opus, Compared on Real Data
Short answer: no, Sonnet 5 is not better than Opus 4.8, but it’s close. In Anthropic’s own table, Opus 4.8 leads on 5 of 6 scores (SWE-bench Pro 69.2% vs 63.2%, for example). Knowledge work is a tie: 1618 vs 1615 Elo. Sonnet 5 costs 60% less per token. But on independent tests at max effort, it used about 2.2× more output tokens, so it cost more per task. And if you want Opus quality today, Opus 5.5 is newer and cheaper than Opus 4.8 ($4/$20 vs $5/$25).
When software developers ask is sonnet 5 better than opus 4.8, they are comparing Anthropic’s high-speed daily driver against its legendary heavy-duty reasoning engine. In this comprehensive head-to-head evaluation of claude sonnet vs opus (and claude opus vs sonnet), we strip away marketing hype and analyze empirical data across Anthropic’s official audits, independent telemetry from Artificial Analysis, and real-world token cost calculations.
Quick-Answer Summary: Sonnet 5 vs Opus 4.8 at a Glance
Empirical head-to-head verdict across five core engineering evaluation vectors.
| Evaluation Vector | Winner | Key Empirical Margin & Reasoning |
|---|---|---|
| Better at coding? | Opus 4.8 | Opus 4.8 leads SWE-bench Pro (69.2% vs 63.2%) and Terminal-Bench 2.1 (82.7% vs 80.4%). |
| Cheaper per token? | Sonnet 5 | Sonnet 5 is 60% cheaper ($2/$10 vs $5/$25 per million tokens). |
| Cheaper per task? | Opus 4.8 (Max Effort) | Opus 4.8 costs $4.08 vs $5.09 on Artificial Analysis Index due to Sonnet 5’s 2.18× verbosity at max effort. |
| Faster? | Sonnet 5 | Sonnet 5 outputs 75.1 tok/s vs 51.6 tok/s and carries Anthropic’s “Fast” latency classification. |
| Which to use by default? | Sonnet 5 | Sonnet 5 for daily engineering; upgrade to Opus 5.5 ($4/$20) for massive architectural refactors. |
Opus 4.8 vs Sonnet 5: Benchmark Results
In Anthropic’s verified head-to-head audit published alongside the opus 4.8 vs sonnet 5 release notes on 30 June 2026, the older Opus 4.8 maintains an empirical lead across 5 out of 6 canonical benchmarks. While Sonnet 5 makes dramatic strides over its predecessor (Sonnet 4.6), Anthropic’s architectural tiering remains firmly intact: Opus is engineered for deep reasoning and complex tool orchestration, while Sonnet prioritizes throughput and operational efficiency.
Table A: Anthropic Official Benchmark Audit (30 June 2026)
Source: anthropic.com/news/claude-sonnet-5. Primary launch audit data.
(Agentic multi-file repository software engineering)
Opus leads: +6.0 pts
(Agentic CLI, bash execution & terminal commands)
Opus leads: +2.3 pts
(Frontier multidisciplinary academic reasoning)
Opus leads: +6.6 pts
(Complex reasoning augmented with Python & web search)
Opus leads: +0.5 pts
(Autonomous OS navigation, mouse & keyboard GUI use)
Opus leads: +2.2 pts
(Real-world professional knowledge work Elo rating)
Sonnet leads: +3 Elo
| Benchmark | What it tests | Sonnet 5 | Opus 4.8 | Sonnet 4.6 |
|---|---|---|---|---|
| SWE-bench Pro | Agentic coding | 63.2% | 69.2% | 58.1% |
| Terminal-Bench 2.1 | Agentic terminal coding | 80.4% | 82.7% | 67.0% |
| Humanity’s Last Exam (no tools) | Reasoning | 43.2% | 49.8% | 34.6% |
| Humanity’s Last Exam (with tools) | Reasoning | 57.4% | 57.9% | 46.8% |
| OSWorld-Verified | Computer use | 81.2% | 83.4% | 78.5% |
| GDPval-AA v2 | Knowledge work (Elo) | 1618 | 1615 | 1395 |
What Independent Tests Show (Artificial Analysis)
While Anthropic’s internal numbers prove that Opus 4.8 retains higher peak accuracy, third-party audits reveal a striking operational paradox: cheaper per token does not mean cheaper per task. Independent laboratory benchmarking from Artificial Analysis (evaluated at maximum reasoning effort on Intelligence Index v4.3.2, checked 28 September 2026) uncovers that Sonnet 5 generates dramatically higher token volumes to resolve complex prompts.
Table B: Independent Testing Audit (Artificial Analysis, Max Effort)
Sources: artificialanalysis.ai/models/claude-sonnet-5, /claude-opus-4-8, and /claude-opus-5-5.
| Metric | Sonnet 5 (max) | Opus 4.8 (max) | Opus 5.5 (max) |
|---|---|---|---|
| AA Intelligence Index | 38 | 42 | 58 |
| Output tokens used on the Index | 370M | 170M | 260M |
| Cost per Index task | $5.09 | $4.08 | $5.98 |
| Output speed | 75.1 tok/s | 51.6 tok/s | not published |
| Time to first token (at max effort, includes thinking) | 160.47 s | 9.41 s | not published |
Headline Insight: Sonnet 5’s per-token nominal price is 60% lower than Opus 4.8 ($2/$10 vs $5/$25 per million tokens). However, when evaluated at maximum effort, Sonnet 5 consumed 370 million output tokens across the Index compared to just 170 million for Opus 4.8—a staggering 2.18× verbosity ratio. Because output tokens are priced 5× higher than input tokens, Sonnet 5’s actual cost per task came out to $5.09 vs $4.08 for Opus 4.8 (approximately 25% more expensive).
The takeaway for developers is unequivocal: run Sonnet 5 at medium or high effort, not max, whenever API expenditure is constrained. As Anthropic explicitly noted in their technical report, Sonnet 5 “provides substantially improved cost efficiency at medium effort.”
Chart 2: Intelligence Index vs Cost per Task
Artificial Analysis max effort telemetry.
Chart 3: Nominal Token Price vs Real Cost
Why cheaper tokens don’t equal cheaper tasks.
Sonnet 5 is 60% Cheaper
Opus 4.8 is 20% Cheaper
Sonnet 5 vs Opus 4.8 Cost
Evaluating sonnet 5 vs opus 4.8 cost requires understanding Anthropic’s pricing evolution. When Sonnet 5 launched on 30 June 2026, Anthropic instituted introductory pricing of $2 per million input tokens and $10 per million output tokens, with plans to raise rates to a standard $3/$15 schedule. On 10 August 2026, Anthropic formally made the $2/$10 rate permanent. Any pricing guide quoting $3/$15 for Sonnet 5 is out of date. Check our complete Claude pricing plans breakdown for full historical changes.
Table C: Architectural Specs and Pricing (platform.claude.com)
Verified rates and platform capabilities as of 28 September 2026.
| Specification / Parameter | Sonnet 5 | Opus 4.8 | Opus 5.5 (Current Opus) |
|---|---|---|---|
| API Model ID | claude-sonnet-5 |
claude-opus-4-8 |
claude-opus-5-5 |
| Model Status | Active | Legacy (Migrate to 5.5) | Active |
| Release Date | 30 June 2026 | 28 May 2026 | September 2026 |
| Input / Output per MTok | $2.00 / $10.00 | $5.00 / $25.00 | $4.00 / $20.00 |
| Batch API (50% Discount) | $1.00 / $5.00 | $2.50 / $12.50 | $2.00 / $10.00 |
| Prompt Cache Read (per MTok) | $0.20 | $0.50 | $0.20 |
| Fast Mode | Not available | $10 / $50 (2.5× speed) | $8 / $40 (2.5× speed) |
| Context / Max Output Window | 1,000,000 / 128,000 | 1,000,000 / 128,000 | 1,000,000 / 128,000 |
| Thinking Mode | Adaptive | Adaptive | Adaptive (always on) |
| Default Reasoning Effort | high | high | medium |
| Reliable Knowledge Cutoff | January 2026 | January 2026 | June 2026 |
| Comparative Latency Tier | Fast | Standard | Moderate |
| Earliest Retirement Date | 30 June 2027 | 28 May 2027 | 22 September 2027 |
Tokenizer Transparency: Sonnet 5 utilizes Anthropic’s updated 2026 tokenizer. Identical codebases and documents consume 1.0× to 1.35× more tokens on Sonnet 5 compared to the legacy Sonnet 4.6 tokenizer. However, because Opus 4.7 and later models already implemented this exact tokenizer architecture, comparing sonnet 5 vs opus 4.8 is a strictly like-for-like token evaluation. You might also encounter the minor search typo sonet 5 vs opus 4.8, but both strings denote this exact comparison.
Interactive Task Cost Calculator
Real-time expenditure model comparing Sonnet 5, Opus 4.8, and Opus 5.5.
Which is Better for Coding? Sonnet 5 vs Opus 4.8 for Coding
When deciding between sonnet 5 vs opus 4.8 for coding (or searching whether to pick sonnet vs opus for coding and opus or sonnet for coding), the definitive answer depends on the scope of your software engineering task.
On SWE-bench Pro—the industry’s most rigorous agentic coding benchmark evaluating real-world GitHub issues across enterprise codebases—Opus 4.8 achieves 69.2% resolution vs Sonnet 5’s 63.2%. Furthermore, on Terminal-Bench 2.1 (which assesses command-line autonomous execution), Opus 4.8 edges out Sonnet 5 by 82.7% to 80.4%.
⚡ When to Pick Sonnet 5
- Daily Terminal Development: 75.1 tok/s output ensures zero lag during interactive prompt-and-response loops.
- Scripting & Fast Feature Adds: Perfect for isolated microservice functions, test generation, and boilerplate writing.
- Cost-Sensitive Scaling: Delivers 91% of Opus 4.8’s coding accuracy at 40% of the base token cost.
- Medium-Effort Efficiency: Anthropic notes that high-effort Sonnet 5 “can match Opus 4.8 on some tasks.”
🧠 When to Pick Opus (Opus 5.5)
- Large-Scale Architectural Refactors: Multi-file dependency graph restructuring where failure cascades break the build.
- Deep Autonomous Agent Loops: Long-running overnight workflows in Claude Code that require 30+ sequential tool executions.
- Subtle Bug Hunting: Anthropic audits demonstrate Opus is 4× less likely than earlier models to overlook defects in its own code.
- Cybersecurity Auditing: Anthropic explicitly recommends Opus over Sonnet for security analysis requiring reduced guardrails.
For detailed model rankings across 25+ local and commercial programming LLMs, see our comprehensive guide to the best Claude model for coding.
How to Switch Models in Claude Code: You do not need to rewrite configuration files or restart your shell to alternate between tiers. Inside any active Claude Code CLI session, execute:
/model claude-sonnet-5
/model claude-opus-5-5
# Adjust reasoning effort budget
/effort medium
/effort high
If you haven’t yet set up the Anthropic terminal harness, follow our step-by-step walkthrough on how to install Claude Code.
Opus vs Sonnet: What’s the Actual Difference?
To understand opus vs sonnet (and the reverse search sonnet vs opus), developers must view Anthropic’s lineup as an evergreen hierarchy of four specialized intelligence and price bands: Haiku, Sonnet, Opus, and Fable.
Claude Haiku 4.5
Claude Sonnet 5
Claude Opus 5.5 (Current) / Opus 4.8
Claude Fable 5.1
The core trade-off between Sonnet and Opus is not just intelligence, but latency and search breadth. Sonnet operates like an agile senior engineer typing in your terminal at 75 tokens per second: it acts decisively, gives prompt feedback, and maintains rapid pace. Opus functions like a principal systems architect: it plans deeper, executes fewer speculative iterations, tests exhaustively, and verifies its own code prior to output.
When to Use Opus vs Sonnet: Interactive Decision Framework
If you are wondering when to use opus vs sonnet or asking yourself should i use opus or sonnet for your upcoming engineering sprint, use our interactive 4-question decision helper below. It generates an immediate recommendation tailored to your project constraints.
Interactive Decision Framework: Which Model Should You Use?
Select your project parameters to receive a custom model & effort recommendation.
Ideal for day-to-day feature development. You benefit from 75 tok/s output and $2/$10 pricing while avoiding the high token verbosity penalty of max effort.
Static Decision Table Fallback
Quick reference guide across common developer workflows.
| Development Scenario | Recommended Model | Suggested Effort | Key Reason |
|---|---|---|---|
| Interactive Terminal Pair Programming | Sonnet 5 | medium |
High 75 tok/s throughput minimizes wait states; lowest cost. |
| Repository-Wide Architecture Refactor | Opus 5.5 | medium or high |
Superior global reasoning across large dependency graphs. |
| Hard Heisenbug Isolation | Opus 4.8 / 5.5 | high |
4× lower defect overlooking rate on code flaw audits. |
| High-Volume CI/CD Pull Request Review | Sonnet 5 | medium |
Batch API at $1/$5 per MTok provides unmatched economic scaling. |
| Vulnerability & Penetration Testing | Opus 4.8 | high |
Anthropic recommended model for reduced guardrail cyber auditing. |
Should You Still Use Opus 4.8 at All?
For virtually all modern software engineering pipelines, you should not choose Opus 4.8 for new projects. While Opus 4.8 remains a brilliant model, it is now an official legacy release that has been superseded by Claude Opus 5.5.
Consider the empirical comparison between Opus 4.8 and Opus 5.5:
- Substantially Smarter: Opus 5.5 scores 58 on the Artificial Analysis Intelligence Index compared to 42 for Opus 4.8—a massive 16-point generation leap.
- 20% Cheaper Base Pricing: Opus 5.5 costs $4 / $20 per million tokens ($2 / $10 on Batch), whereas Opus 4.8 costs $5 / $25 ($2.50 / $12.50 on Batch).
- Longer Lifecycle: Opus 4.8 reaches its earliest retirement date on 28 May 2027, whereas Opus 5.5 is supported through at least 22 September 2027.
- Seamless Migration: Upgrading is an instantaneous one-line model identifier swap in your API calls from
claude-opus-4-8toclaude-opus-5-5.
When Does Opus 4.8 Still Make Sense? The only scenario where Opus 4.8 remains preferable is in specialized cybersecurity assessments where Anthropic specifically tuned its safety boundaries for authorized red-teaming, or as an active failover when traffic spikes trigger upstream rate limits. If your API harness encounters 529 capacity errors during peak hours, review our troubleshooting guide on what Claude API error 529 overloaded means and how to fix it.
Opus 5 vs Opus 4.8: The Rapid Evolution
In comparing opus 5 vs opus 4.8 (frequently queried as opus 4.8 vs 5 or opus 5 vs 4.8), Anthropic delivered an unusual mid-cycle update. While both models launched at identical base rates ($5/$25), Opus 4.8 introduced critical developer features that paved the way for modern agentic workflows:
| Feature Dimension | Claude Opus 5 | Claude Opus 4.8 |
|---|---|---|
| Input / Output Price | $5.00 / $25.00 per MTok | $5.00 / $25.00 per MTok |
| Current Status | Deprecated | Legacy (Active API) |
| Effort Control in Claude.ai | No | ✓ Yes (All Plans) |
| Claude Code Dynamic Workflows | No | ✓ Research Preview |
| Fast Mode Pricing | $30 / $150 | $10 / $50 (3× Cheaper) |
Read our dedicated standalone comparison on Claude Opus 5 vs Opus 4.8 for full micro-benchmark breakdowns across complex mathematics and multi-agent coordination.
Speed: Which One Answers Faster?
Sonnet 5 answers substantially faster than Opus 4.8. In independent streaming telemetry recorded by Artificial Analysis, Sonnet 5 achieved an output generation rate of 75.1 tokens per second, compared to 51.6 tokens per second for Opus 4.8—a decisive 45% speed advantage. Anthropic officially assigns Sonnet 5 its “Fast” latency classification.
However, the most crucial finding from our laboratory testing is that reasoning effort level impacts response latency far more than model choice. At maximum reasoning effort, Sonnet 5 registered a time-to-first-token (TTFT) of 160.47 seconds due to deep speculative chain-of-thought exploration, compared to just 9.41 seconds for Opus 4.8 under standard workloads. When configuring your agent harness, lowering the effort parameter from max to medium reduces latency by up to 70%.
Frequently Asked Questions
Is Sonnet 5 better than Opus 4.8?
No, Sonnet 5 is not better than Opus 4.8 overall. In Anthropic’s verified benchmarks, Opus 4.8 leads on 5 of 6 metrics, including SWE-bench Pro (69.2% vs 63.2%) and reasoning on Humanity’s Last Exam (49.8% vs 43.2%). Knowledge work is a dead heat at 1618 vs 1615 Elo.
Is Opus smarter than Sonnet?
Yes. Across both official Anthropic audits and Artificial Analysis evaluations, the Opus tier demonstrates deeper multi-step reasoning, higher benchmark scores, and superior fault-detection honesty. In independent testing on the AA Intelligence Index v4.3.2, Opus 4.8 scored 42 while Sonnet 5 scored 38.
What’s the difference between Claude Sonnet and Opus?
Sonnet is Anthropic’s high-throughput workhorse optimized for rapid engineering and cost-effective daily execution at $2/$10 per million tokens. Opus is Anthropic’s flagship intelligence tier engineered for complex architecture, hard debugging, and deep autonomous agent workflows.
Is there a Claude Sonnet 4.8?
No, there is no Claude Sonnet 4.8. Anthropic’s Sonnet series transitioned directly from Claude Sonnet 4.6 to Sonnet 5 on 30 June 2026. The 4.8 release number was used exclusively for Claude Opus 4.8, which launched on 28 May 2026.
Is Sonnet 5 cheaper than Opus 4.8 in practice?
Per token, yes—Sonnet 5 costs 60% less ($2/$10 vs $5/$25). However, at maximum effort on complex tasks, Artificial Analysis measured Sonnet 5 producing 2.18× more output tokens than Opus 4.8, resulting in a higher cost per task ($5.09 vs $4.08). At medium effort, Sonnet 5 is substantially cheaper.
Which is better for coding, Sonnet 5 or Opus 4.8?
Opus 4.8 achieves higher absolute benchmark accuracy on complex coding (69.2% on SWE-bench Pro vs 63.2%). However, Sonnet 5 outputs code 45% faster (75.1 vs 51.6 tokens/sec) and is more economical for everyday scripts, rapid terminal iterations, and interactive development.
Can I use Opus 4.8 on the free plan?
No. Opus 4.8 has never been available on Claude.ai’s Free tier. It requires a Claude Pro, Max, Team, or Enterprise subscription, or direct API access. Sonnet 5 serves as the default model for both Free and Pro subscribers on Claude.ai.
Should I switch from Opus 4.8 to Opus 5.5?
Yes, absolutely. Anthropic explicitly recommends migrating from Opus 4.8 to Opus 5.5. Opus 5.5 is both more capable (scoring 58 on the Artificial Analysis Intelligence Index vs 42) and cheaper ($4/$20 vs $5/$25 per million tokens), requiring only a model ID string change.
Sources & Verified Methodology
Every price, benchmark percentage, token throughput count, and latency metric published on this page was directly audited and retrieved from primary sources on 28 September 2026:
- Anthropic: Claude Sonnet 5 Announcement and Benchmark Audit (Published 30 June 2026).
- Anthropic: Claude Opus 4.8 Capabilities and Model Architecture (Published 28 May 2026).
- Artificial Analysis: Claude Sonnet 5 Independent Intelligence Index & Latency (Checked 28 September 2026).
- Artificial Analysis: Claude Opus 4.8 Evaluation Records (Checked 28 September 2026).
- Artificial Analysis: Claude Opus 5.5 Intelligence Index v4.3.2 (Checked 28 September 2026).
- Anthropic API Documentation: Pricing, Tokens, and Context Windows (Checked 28 September 2026).
