Claude Opus 4 vs Claude Sonnet 4: Key Differences
Claude Sonnet 4 is the better default for everyday coding and content work, while Claude Opus 4 is the model for long, multi-step agentic tasks that run for hours. Anthropic released both models on May 22, 2025 as the Claude 4 generation. They share one architecture family, a 200,000-token context window, and a training data cutoff of March 2025. For a related comparison, see Best AI Coding Assistant.
Claude Sonnet 4 scores 72.7% on SWE-bench Verified at $3 per million input tokens. Claude Opus 4 scores 72.5% on the same test at $15 per million input tokens, which is 5 times the price. The gap between them widens on sustained autonomous work and expert reasoning, where Opus 4 holds focus across thousands of steps.
For a wider view of the model landscape, see AI Comparison.
Quick Comparison Table
The table below summarizes the 8 factors that separate Claude Opus 4 and Claude Sonnet 4 for most buyers: model tier, price, coding scores, context window, output ceiling, speed, reasoning endurance, and free-tier access. For a cross-generation comparison, see Gemini 2.5 Pro vs Claude 3.7 Sonnet.
| Factor | Claude Opus 4 | Claude Sonnet 4 |
|---|---|---|
| Model ID | claude-opus-4-20250514 | claude-sonnet-4-20250514 |
| Best for | Long-horizon agents, deep reasoning, research | Daily coding, chat, content, high-volume apps |
| SWE-bench Verified | 72.5% | 72.7% |
| Terminal-bench | 43.2% | Not published at launch |
| Context window | 200,000 tokens | 200,000 tokens |
| Max output | 32,000 tokens | 64,000 tokens |
| API price (input / output) | $15 / $75 per million tokens | $3 / $15 per million tokens |
| Free on claude.ai | No — paid plans only | Yes, with usage limits |
The two models share the same architecture family, the same 200,000-token context window, and a training data cutoff of March 2025. Price and sustained-task endurance are the practical dividing lines. For the upgrade path from the previous generation, see Claude Sonnet 4 vs Claude 3.5 Sonnet.
What Is Claude Opus 4?
Claude Opus 4 is Anthropic’s frontier model from the Claude 4 generation, built for complex, long-running tasks that require thousands of sequential steps. Anthropic described it at launch as the best coding model in the world and highlighted sustained agent runs lasting several hours. It is a hybrid model: it returns near-instant answers for simple prompts and switches to extended thinking for hard problems.
Claude Opus 4 runs on the Claude API, Amazon Bedrock, and Google Cloud Vertex AI. On claude.ai, it is available to Pro, Max, Team, and Enterprise subscribers, not the free tier. The model powers Claude Opus inside Claude Code, Anthropic‘s agentic command-line coding tool.
Claude Opus 4 supports extended thinking with tool use in beta, which lets it alternate between reasoning and calling tools such as web search during a single response. It can also run tools in parallel and use local files as memory when given file access.
What Is Claude Sonnet 4?
Claude Sonnet 4 is the mid-tier model of the Claude 4 generation, tuned for the balance of speed, cost, and intelligence that most production workloads need. It is a direct upgrade to Claude Sonnet 3.7 and was designed as a drop-in replacement for it. Anthropic made Claude Sonnet 4 available on the free claude.ai tier, subject to usage limits.
Claude Sonnet 4 matches Claude Opus 4 on the SWE-bench Verified coding benchmark, scoring 72.7% versus 72.5%. It runs roughly 2 to 3 times faster than Opus 4 on typical requests and costs one-fifth as much per token.
Claude Sonnet 4 is available through the same channels as Opus 4: the Claude API, Amazon Bedrock, and Google Cloud Vertex AI, plus the Claude Sonnet tier on claude.ai. GitHub selected Claude Sonnet 4 as the model behind the coding agent in GitHub Copilot at launch.
Feature Comparison
Claude Opus 4 and Claude Sonnet 4 expose the same core feature set, and the differences concentrate in 3 areas: sustained task length, output ceiling, and extended reasoning depth.
Extended Thinking and Reasoning
Claude Opus 4 sustains multi-step reasoning across far longer task chains than Claude Sonnet 4. Both models offer extended thinking, where the model works through a problem step by step before answering. Opus 4 holds context and goal focus across thousands of tool calls, which is why Anthropic positions it for autonomous agents.
Claude Sonnet 4 also does extended thinking well for typical problems, but it drifts sooner on very long autonomous runs. For a chat session or a single coding task, the difference is usually invisible. For an agent asked to refactor a large codebase unattended, Opus 4 completes more of the work correctly.
Output Length
Claude Sonnet 4 generates up to 64,000 output tokens in one response, double the 32,000-token ceiling of Claude Opus 4. Sonnet 4 is the better fit when a single call must return a large artifact, such as a full document, a long file, or bulk structured data. Opus 4 concentrates its output budget on dense, high-value reasoning rather than volume.
Coding and Agent Tools
Both models support parallel tool use, extended thinking with tool use in beta, and file-based memory. Claude Opus 4 is the default model in Claude Code for complex work, while Claude Sonnet 4 handles routine edits and reviews at lower cost. Teams often route simple tasks to Sonnet 4 and escalate to Opus 4 only when a task stalls.
Performance Comparison
On headline benchmarks the two models are close, and Claude Opus 4 pulls ahead only on graduate-level reasoning and long autonomous coding.
| Benchmark | Claude Opus 4 | Claude Sonnet 4 |
|---|---|---|
| SWE-bench Verified (coding) | 72.5% | 72.7% |
| Terminal-bench (agentic terminal) | 43.2% | Not published at launch |
| GPQA Diamond (extended thinking) | 75.1% | 70.8% |
| MMMLU multilingual (extended thinking) | 88.0% | 85.8% |
| MMMU visual reasoning (extended thinking) | 74.8% | 73.1% |
| AIME math (extended thinking) | 34.7% | 33.4% |
The SWE-bench result is the headline story: Claude Sonnet 4 edges Claude Opus 4 by 0.2 points on real-world coding tasks, so paying 5 times more does not buy better single-task coding accuracy. Opus 4’s advantage is a 4.3-point lead on GPQA Diamond, a set of expert-written science questions, and its ability to keep working accurately for hours without a human in the loop.
Speed favors Claude Sonnet 4. It returns tokens 2 to 3 times faster than Opus 4 on most prompts, which matters for chat interfaces and any user-facing product where latency is visible.
Pricing
Claude Opus 4 costs $15 per million input tokens and $75 per million output tokens; Claude Sonnet 4 costs $3 and $15, exactly one-fifth as much on both sides. Both models get a 50% discount on the Message Batches API and cheaper prompt-cache reads at 10% of the base input price.
| Item | Claude Opus 4 | Claude Sonnet 4 |
|---|---|---|
| Input, per million tokens | $15.00 | $3.00 |
| Output, per million tokens | $75.00 | $15.00 |
| Batch API | 50% off | 50% off |
| claude.ai access | Pro ($20/month), Max, Team, Enterprise | Free tier and all paid plans |
A task that costs $1.00 on Claude Sonnet 4 costs about $5.00 on Claude Opus 4 for the same token volume. That ratio makes Sonnet 4 the economical choice for high-volume applications and Opus 4 a targeted tool for the tasks that justify the premium. For a broader pricing overview across vendors, see Best AI Models.
Pros and Cons
Each model carries a clear set of trade-offs that follow directly from its price and design goal. The lists below cover 4 strengths and 4 weaknesses for each model.
Claude Opus 4 Pros and Cons
Claude Opus 4 has 4 notable strengths and 4 notable weaknesses relative to Claude Sonnet 4. For a related comparison, see Claude Code vs GitHub Copilot.
Pros:
– Best-in-class sustained performance on multi-hour autonomous tasks
– 4.3-point lead over Sonnet 4 on GPQA Diamond expert reasoning
– Higher scores on multilingual, visual, and math benchmarks
– Default model for complex work in Claude Code
The 4 drawbacks below all trace back to price and output limits.
Cons:
– 5 times the token cost of Claude Sonnet 4
– No SWE-bench advantage despite the price premium
– Lower 32,000-token maximum output
– Not available on the free claude.ai tier
Claude Sonnet 4 Pros and Cons
Claude Sonnet 4 has 4 notable strengths and 4 notable weaknesses relative to Claude Opus 4.
Pros:
– Matches Opus 4 on SWE-bench Verified at one-fifth the price
– 64,000-token maximum output, double that of Opus 4
– 2 to 3 times faster response speed
– Available on the free claude.ai tier
Cons:
– Drifts sooner than Opus 4 on very long autonomous agent runs
– Trails Opus 4 by 4.3 points on GPQA Diamond
– Lower scores on multilingual and visual reasoning tests
– Extended thinking depth is capped below Opus 4 for the hardest problems
User Reviews
Developer sentiment favors Claude Sonnet 4 as the daily driver and reserves Claude Opus 4 for tasks that stall. On developer forums and Reddit threads, the recurring conclusion is that Sonnet 4 handles most coding, debugging, and writing at a quality that does not justify Opus 4’s cost for routine use.
Users who run autonomous agents report the opposite preference. Long unattended coding jobs, large refactors, and research agents that chain many tool calls are the cases where reviewers say Opus 4 clearly earns its price. Several teams describe a hybrid setup where Sonnet 4 does first-pass work and Opus 4 is invoked only on escalation.
Common complaints target cost predictability rather than output quality. Extended thinking and agent loops consume tokens quickly, and Opus 4 output at $75 per million tokens can produce surprising bills when an agent runs longer than expected.
Use Cases
When Claude Opus 4 Is the Better Fit
Claude Opus 4 fits 4 use cases best: autonomous coding agents that run for hours, large-scale refactors across many files, research assistants that chain dozens of tool calls, and expert-domain reasoning in science, law, or finance where the GPQA-style accuracy gap matters.
When Claude Sonnet 4 Is the Better Fit
Claude Sonnet 4 fits 4 use cases best: interactive coding assistants, customer-facing chatbots, high-volume content and summarization pipelines, and any product where per-request cost and latency are hard constraints.
Using Both Together
Many teams route requests by difficulty. Claude Sonnet 4 handles the default path, and a task that fails a quality check or exceeds a step budget is retried on Claude Opus 4. This pattern captures most of Opus 4’s benefit while keeping the average cost close to Sonnet 4 rates.
Final Recommendation
Choose Claude Opus 4 for autonomous, long-horizon tasks, and Claude Sonnet 4 for interactive coding, chat, and high-volume work. The 4 conditions under each model below make the choice concrete.
Choose Claude Opus 4 if:
– You run autonomous agents that work for hours without supervision
– Your tasks chain thousands of steps or dozens of tool calls
– Expert-level reasoning accuracy outweighs token cost
– You already escalate hard tasks and want the strongest available model
Choose Claude Sonnet 4 if:
– You need strong coding performance at predictable cost
– Your workload is high-volume chat, content, or summarization
– Response latency is visible to end users
– You want a capable model on the free claude.ai tier
Alternatives
If neither model fits, 4 other options are worth evaluating. Claude Opus 4.1 refined Opus 4’s coding and agent behavior in August 2025 and is a direct upgrade for Opus 4 users. Claude Sonnet 4.5 and the newer Claude Opus 5 and Sonnet 5 generation extend the same lineup with higher benchmark scores and a 1-million-token context window. GPT-5 from OpenAI and Gemini 2.5 Pro from Google are the closest cross-vendor competitors on coding and reasoning. For head-to-head detail, see GPT-5 vs Claude Opus 4.1 and Claude Alternatives.
FAQ
Is Claude Opus 4 Better Than Claude Sonnet 4 for Coding?
Not on single-task benchmarks. Claude Sonnet 4 scores 72.7% on SWE-bench Verified versus 72.5% for Claude Opus 4. Opus 4 only pulls ahead on long autonomous coding runs that continue for hours across many steps.
How Much More Expensive Is Claude Opus 4?
Claude Opus 4 costs exactly 5 times more than Claude Sonnet 4 per token. Opus 4 is $15 per million input tokens and $75 per million output tokens, while Sonnet 4 is $3 and $15. Both models get 50% off on the Batch API.
Do Claude Opus 4 and Claude Sonnet 4 Have the Same Context Window?
Yes. Both models have a 200,000-token context window and a training data cutoff of March 2025. The output ceiling differs: 32,000 tokens for Opus 4 and 64,000 tokens for Sonnet 4.
Is Claude Sonnet 4 Free to Use?
Yes, with limits. Claude Sonnet 4 is available on the free claude.ai tier subject to usage caps. Claude Opus 4 requires a Pro, Max, Team, or Enterprise plan, or API access.
Should I Upgrade From Claude Sonnet 4 to Claude Opus 4?
Only for specific tasks. Upgrade when a job runs autonomously for hours, chains many tool calls, or needs expert-domain reasoning. For interactive coding, chat, and content work, Claude Sonnet 4 delivers comparable quality at one-fifth the cost.
Final Verdict
Claude Sonnet 4 is the right default and Claude Opus 4 is a targeted upgrade, not a general one. Sonnet 4 matches Opus 4 on real-world coding, generates longer outputs, responds faster, and costs one-fifth as much. Claude Opus 4 justifies its 5-times price only on long autonomous agent runs and expert reasoning tasks.
The most cost-effective setup for most teams routes everyday work to Sonnet 4 and escalates to Opus 4 only when a task genuinely needs it. For related comparisons, see Claude 3.5 Sonnet vs Claude 3 Opus and Claude vs ChatGPT.
