Claude Sonnet 5: Price, Specs & Verdict (2026)

Claude Sonnet 5 is Anthropic's balanced daily-driver model, released 30 June 2026 as a drop-in upgrade to Sonnet 4.6. It pairs near-Opus reasoning with lower cost — $3 per million input tokens and $15 per million output — a 1M-token context window, and adaptive thinking on by default. It's the default model on Claude's Free and Pro plans.

Pricing, specs, and lineup position verified 9 August 2026 against Anthropic's model overview. The introductory rate expires 31 August 2026.

We've run it as our default for everything from bug hunts to drafting these posts, and the short version is simple: it's the model most people should reach for first. Opus is still the heavyweight and Haiku 4.5 is still the cheap sprinter, but this is the one that quietly handles 80% of the work. For the full lineup, our Claude models explained pillar maps every tier.

What is Claude Sonnet 5?

Anthropic's most agentic mid-tier model, released 30 June 2026 as a drop-in upgrade to Sonnet 4.6. It plans multi-step work, then uses tools — browsers, terminals, file systems — to finish the job on its own.

That "finish the job, don't just answer the question" framing is the whole point, and it's laid out in Anthropic's launch announcement.

Three things changed under the hood versus 4.6, and they matter more than the version bump suggests. Adaptive thinking is now on by default, so the model decides how long to reason instead of waiting for you to flip a switch — an evolution of Claude's extended thinking. Manual extended thinking is gone: set a thinking budget and the API returns a 400 error. And sampling parameters (temperature, top_p, top_k) no longer accept non-default values. If you're migrating code, those are the three lines to check.

Pricing and the introductory window

$3 per million input tokens and $15 per million output at standard rates — with an introductory $2/$10 running through 31 August 2026, which makes it temporarily cheaper than the model it replaces.

Here's how it sits against the rest of the current lineup:

On the consumer side, none of this touches you directly: it's the default model on the Free and Pro plans, so a $20-per-month Claude Pro plan gets you the model with generous limits and no per-token math. Per-token pricing only applies through the API. If you're comparing tiers on price, our Anthropic Claude API pricing breakdown has the batch and prompt-caching rates too.

Is it faster and cheaper than Opus?

Yes on both — and it now beats the Opus line outright on some agentic work. But Opus still leads where a single wrong turn is expensive.

The question we get most is whether this makes Opus redundant. It doesn't, but it narrows the gap enough that the default should flip. The clearest evidence: it scores 80.4 on Terminal-Bench 2.1 against Opus 4.8's 74.6 — a mid-tier model outscoring the flagship on agentic terminal tasks. Opus still pulls ahead on deep coding (SWE-bench Pro 69.2 vs 63.2) and olympiad-level maths (USAMO 96.7 vs 79.5), where reasoning depth compounds.

The way we think about it: run this by default, and escalate to Opus only when it visibly struggles — a refactor it can't hold in its head, a proof it keeps botching. For a deeper split, we compared them head-to-head in Claude Sonnet vs Opus.

Note that Opus 4.8 remains callable as a legacy model at the same $5/$25 as Opus 5, which is why some benchmark comparisons still cite it.

Everyday coding and writing

The two workloads it handles best are exactly the ones most people have: writing code and writing prose.

For coding, the agentic upgrades show. Point Claude Code at a repo and it will read files, run the test suite, and iterate on a fix without you narrating each step — the finish-the-job behaviour Anthropic tuned for. It's the model we leave selected in the terminal for routine feature work, reserving Opus for the gnarly stuff.

For writing, the near-Opus reasoning means drafts need less cleanup. It holds a brief, keeps a consistent voice across a long document, and follows structural instructions ("lead with the answer, then three examples") more reliably than 4.6 did. It won't generate images — Claude is a text and code model, full stop — but for the words themselves it's the best value in the lineup.

The 1M-token context window and the new tokenizer

1M tokens by default, with no smaller variant to choose. The catch: a new tokenizer produces roughly 30% more tokens for the same text than Sonnet 4.6 did.

A 1M window holds a mid-size codebase or a stack of long documents in a single prompt. If you want the mechanics of how that much context behaves in practice, we cover it in Claude's context window.

The tokenizer change is the gotcha that trips up developers migrating from 4.6. Nothing about the API shape changes, but three things you budget in tokens do. Your max_tokens limit, tuned for 4.6, may now truncate equivalent output. Your context window holds less actual text than the raw 1M suggests. And a request's cost can rise even though the per-token price didn't.

When we moved our own drafting scripts across, this was the only thing that genuinely bit us. A couple of long-context runs quietly truncated because a max_tokens ceiling tuned for 4.6 was suddenly too low for the same output. Recounting our prompts against the new model took a few minutes and fixed it; assuming the old numbers would carry over just cost us a wasted re-run. It's a dull migration step, but it's the one we'd flag first to anyone scripting against the API.

When it's the right pick

Make it your default and only deviate for a reason. Escalate to Opus for the hardest reasoning; drop to Haiku when volume and latency matter more than depth.

If you're weighing the cheaper tier, Claude Haiku vs Sonnet walks through where Haiku's speed wins and where it falls short. The honest summary: this is the model you should have selected unless you have a specific reason not to. It's fast enough to feel responsive, cheap enough to run all day, and smart enough that reaching for Opus becomes the exception rather than the habit.

The quick version:

• The balanced daily-driver for coding and writing
• Costs $3 in / $15 out ($2/$10 intro) per million
• Faster and cheaper than Opus, and wins some agentic benchmarks outright
• Start here; escalate to Opus only when needed

Claude pricing at a glance

Sonnet 5 is included on every paid plan and on the free tier. Per-token billing at $3/$15 only applies if you call it through the API.

For the full breakdown of every plan, see our how much Claude costs guide.

Looking for the version in between? There is no Claude Sonnet 4.7 — the Sonnet line went 4.6 straight to 5, and the 4.7 you have seen is an Opus.