Claude Sonnet 5 is Anthropic’s default, cost efficient model for everyday coding, writing, and analysis. Claude Opus 4.8 costs more and is built for the hardest reasoning and long, autonomous agentic tasks. Most people should start with Sonnet and move to Opus only when a job clearly needs the extra accuracy.
What Separates Claude Opus From Claude Sonnet
Anthropic sells Claude in three main tiers below its newest Mythos class: Haiku for speed, Sonnet for everyday work, and Opus for the hardest problems. As of July 2026, the current lineup is Claude Opus 4.8, released May 28, 2026, and Claude Sonnet 5, released June 30, 2026. Both models share a 1 million token context window and a 128,000 token output limit, so the real gap between them is depth of reasoning, price, and how much autonomy each one can handle on a long task.
Sonnet 5 was built to close the gap with Opus rather than replace it. Anthropic’s own Sonnet 5 announcement says the model narrows the distance to Opus 4.8 on many evaluations and, on some coding tasks, reaches similar capability levels. It also reports a lower rate of undesirable agentic behavior compared with Sonnet 4.6, alongside a noticeably weaker ability to carry out cybersecurity tasks than Anthropic’s Opus-tier models, a distinction worth knowing if you’re weighing Sonnet for security researc
Claude Opus 4.8 Vs Sonnet 5 Pricing
Price is where the two models split the most
Claude Opus 4.8 Pricing
Opus 4.8 costs 5 dollars per million input tokens and 25 dollars per million output tokens through the Claude API, the same rate Anthropic set for Opus 4.7. A faster mode is available at 10 dollars input and 50 dollars output per million tokens, roughly two and a half times quicker for time sensitive jobs. Cached input reads drop to 0.50 dollars per million tokens, a 90 percent discount off the standard rate.
Claude Sonnet 5 Pricing
Sonnet 5 launched at an introductory rate of 2 dollars per million input tokens and 10 dollars per million output tokens. That pricing holds through August 31, 2026, after which it moves to the standard rate of 3 dollars input and 15 dollars output per million tokens, still a fraction of Opus. One caveat: Sonnet 5 uses an updated tokenizer that can turn the same piece of text into roughly 10 to 35 percent more tokens than Sonnet 4.6 used, so a straight per-token comparison undersells the older model’s efficiency a little.
Performance And Benchmarks
Anthropic’s Sonnet 5 announcement includes cost-to-performance charts that place the new Sonnet close to Opus 4.8 on several evaluations, especially coding and agentic work, while Sonnet 4.6 fell well short of Opus on the same charts. That’s a real jump for the Sonnet line, though Opus 4.8 still leads on the longest, most autonomous tasks: multi-step codebase migrations, extended research runs, and work where one early mistake compounds later on. If your workload is short, well-scoped requests, Sonnet 5’s gap with Opus is small enough that the price difference usually decides the question on its own.
Independent outlets have published their own head-to-head numbers for the two models on benchmarks like SWE-bench, but figures vary by test harness and methodology from one write-up to the next. Treat any single third-party score as a data point rather than the final word, and check Anthropic’s own model cards if a benchmark result is deciding a purchasing decision for your team.
Context Window And Output Limits
Both Opus 4.8 and Sonnet 5 ship with a 1 million token context window and up to 128,000 tokens of output on the standard Messages API, and Anthropic bills long requests at the same per-token rate as short ones. A 900,000 token prompt costs no more per token than a 9,000 token one. Haiku 4.5, by contrast, stays capped at 200,000 tokens of context, which matters if your task involves feeding an entire codebase or a long set of documents into a single request.
Effort And Thinking Modes
Both models use what Anthropic calls adaptive thinking, where Claude decides on its own how long to reason before answering, controlled through an effort parameter set to low, medium, high, xhigh, or max. Opus 4.8 defaults to high effort across the Claude API, Claude Code, and claude.ai, and it no longer accepts a manual thinking-token budget the way older models did; setting one returns an error. Sonnet 5 defaults to high effort on the API and in Claude Code too. Turning effort down is one of the simplest ways to cut cost and latency on either model without switching tiers at all.
When To Use Claude Sonnet 5
Sonnet 5 is a reasonable starting point for most day-to-day work: writing, everyday coding, document and spreadsheet creation, research summaries, and general problem solving. It also handles computer use and vision tasks well, and it’s the default model on Anthropic’s Free and Pro claude.ai plans, so most people are already using it without picking it directly. Start with Sonnet and only move up if a task clearly needs more.
When To Use Claude Opus 4.8
Opus 4.8 earns its higher price on jobs where being wrong costs more than the extra tokens: large-scale code migrations, long-horizon agent runs with many steps, legal or compliance-heavy document review, and cybersecurity work that needs Anthropic’s stronger Opus-tier safeguards. If a task involves biology or security research specifically, Anthropic recommends starting with Opus even on accounts that default to a higher tier model, since those topics route to Opus regardless of your selection. Anthropic also positions Opus 4.8 as the model worth trying again on problems that stumped Sonnet on an earlier attempt.
Availability On Claude Plans And Claude Code
On claude.ai, the Free plan includes Haiku and Sonnet only. Pro, Max, Team, and Enterprise plans add Opus and Anthropic’s newest Fable tier on top, along with a higher rate limit. Both Opus 4.8 and Sonnet 5 are available through the Claude API, Claude Code, Amazon Bedrock, Google Cloud, and Microsoft Foundry, under the model IDs claude-opus-4-8 and claude-sonnet-5.
How To Switch Between Opus And Sonnet
In the claude.ai model picker, switching models takes one click, and you can change models in the middle of an existing conversation without losing history. In the API, switching means changing the model string in your request and confirming your prompt still performs the way you expect, since the two models don’t always respond identically to the same instructions. A practical routing pattern many teams use: send routine turns to Sonnet 5 and escalate to Opus 4.8 only for the specific steps that need it, rather than running an entire session on the pricier model.
Quick Takeaway
Sonnet 5 is the better default for nearly all everyday writing, coding, and analysis work, at a fraction of Opus 4.8’s price. Save Opus 4.8 for the long, high-stakes, or highly autonomous jobs where its extra reasoning depth actually changes the outcome, and use the effort parameter on either model to control cost before you consider switching tiers at all.
FAQ’S
Is Claude Opus 4.8 Or Sonnet 5 Better For Coding?
For most coding tasks, Sonnet 5 is close enough to Opus 4.8 in quality that its lower price makes it the better default. Move to Opus 4.8 for large, multi-file refactors or long-running agentic coding sessions where an early mistake carries through the rest of the task.
How Much Cheaper Is Sonnet 5 Than Opus 4.8?
At introductory pricing through August 31, 2026, Sonnet 5 costs 2 dollars per million input tokens and 10 dollars per million output tokens, against 5 dollars and 25 dollars for Opus 4.8. Even after Sonnet 5 moves to its standard 3 dollar and 15 dollar rate in September, it stays well under half of Opus 4.8’s price
Can I Switch Between Opus And Sonnet Mid Conversation?
Yes. On claude.ai, you can change the model from the picker at any point in an existing chat, and earlier messages stay in context. In the API, you control this by changing the model string on each request.
Does Sonnet 5 Support The Same Context Window As Opus 4.8?
Yes, both currently ship with a 1 million token context window and up to 128,000 tokens of output on the standard Messages API. Haiku 4.5 is the exception in Anthropic’s lineup, capped at 200,000 tokens.
Which Model Is Available On The Free Claude Plan?
The Free plan on claude.ai includes Haiku and Sonnet. Opus and Anthropic’s Fable tier require a Pro plan or higher.
