What Is the Best Claude Model in 2026? Latest Claude Models Compared

For most of Claude's history, choosing a model meant picking one of three sizes: Haiku for speed, Sonnet for balance, and Opus for the hardest work.

That changed in 2026. Anthropic opened a tier above Opus to everyone with Fable 5 in June, then shipped Sonnet 5, Opus 5, Fable 5.1, and a 5.5 generation of Opus, Sonnet, and Haiku over the following four months. The lineup is now four tiers wide, and each new release moved the line between what needs a top-tier model and what doesn't.

A lineup that wide makes a single default harder to justify. Anthropic's model guidance points most workloads at Opus 5.5, while its pricing guidance recommends Haiku for simple tasks and Sonnet for most production work, and each is right for different steps of the same application.

So the best Claude model in 2026 comes down to a comparison of pricing and capability for each step, rather than one pick for the whole application.

What Is the Best Claude Model in 2026?

Claude Fable 5.1 is the top of Anthropic's generally available lineup in 2026, and Claude Opus 5.5 is the stronger default for most workloads at 40% of the price. In production, the best setup is usually a mix: Haiku 5.5 for high-volume steps, Sonnet 5.5 for steps that need more judgment, Opus 5.5 for decisions, and Fable 5.1 when Opus falls short.

Per-token price is only part of the decision. A cheaper model that needs two extra turns to finish a step can cost more than a pricier one that gets it right the first time, which is why cost per completed task is the number that settles which tier a step belongs on.

Measured latency for every Claude model sits next to its price in Respan's Anthropic model catalog, which makes it the quickest way to compare the lineup on the numbers that affect a routing decision.

What Is the Latest Claude Model?

The newest Claude model is Claude Haiku 5.5, which Anthropic released on October 7, 2026, about two weeks after Opus 5.5 and nine days after Sonnet 5.5. It replaces Haiku 4.5 at the bottom of the lineup and drops the list price to $0.10 per million input tokens and $0.50 per million output tokens on prompts up to 100K tokens.

The change that matters most for production cost is that Haiku now shares the rest of the lineup's limits: a 1M-token context window, a 128K output ceiling, adaptive thinking, and the effort parameter. Steps that used to be ruled out of the bottom tier by size alone can now run there, and past 100K tokens the rate rises to $0.50 and $2.50, still a quarter of Sonnet 5.5's.

Fable 5.1, released September 1 alongside Claude Mythos 5.1, is still the top of the generally available lineup. It kept Fable 5's $10/$50 list price, and Anthropic cut Fable 5.1's cache read price by 75%, to $0.25 per million tokens. Mythos 5.1 is the same underlying model with more permissive safeguards for cybersecurity and life sciences work, available only through Anthropic's trusted access programs.

Being newest doesn't make Haiku 5.5 the default, though. Opus 5.5 is still the right starting point for most workloads, and Haiku 5.5 earns its place on the steps that clear your evals at a fraction of the cost.

Plus, there are new models being released almost daily that are changing the game, like the new Jev model by TypeSafe.

List of All Current Claude Models

Anthropic's current lineup has four generally available models, one per tier, from Haiku at the bottom to Fable at the top. Older versions such as Fable 5, Opus 5, Sonnet 5, and Haiku 4.5 are still available on the Claude API, but new work should target the four below them.

Claude Fable 5.1

Anthropic positions Claude Fable 5.1 (claude-fable-5-1) for demanding reasoning and long-horizon agentic work, the kind of task that runs unattended for hours and has to check its own progress along the way. Adaptive thinking is always on and can't be turned off, and its comparative latency is the slowest in the lineup.

Because one of Anthropic's stated reasons for moving to Fable is that Opus 5.5 at higher effort still falls short, raising effort on Opus is the step to try before paying Fable's rate, and the Claude Fable vs Opus comparison shows how that tradeoff plays out in cost per completed task.

Claude Opus 5.5

Most teams should start on Claude Opus 5.5 (claude-opus-5-5), according to Anthropic's model overview, which describes it as the model for long-running agentic coding and knowledge work. It costs $4/$20, down from $5/$25 on Opus 5, and it's the default model in Claude Code on Pro, Max, Team, Enterprise, and API accounts.

Opus 5.5 shares Sonnet 5.5's 1M context window and 128K output ceiling, so moving work between the two is usually just a model-string change. Unlike Sonnet, its adaptive thinking is always on, and it defaults to medium effort rather than high. It also supports Fast mode, in research preview, at $8/$40 for significantly faster output, which has no Sonnet equivalent.

Claude Sonnet 5.5

At $2/$10, Claude Sonnet 5.5 (claude-sonnet-5-5) costs half of Opus 5.5 on both input and output, and Anthropic describes it as the best combination of speed and intelligence in the lineup. It keeps Sonnet 5's price, and its reliable knowledge cutoff moves up to June 2026.

Sonnet 5.5 is the natural default for well-specified production steps that need more judgment than Haiku gives, where the output gets checked by a test or a schema before it does anything.

Claude Haiku 5.5

Claude Haiku 5.5 (claude-haiku-5-5) is the cheapest current model at $0.10/$0.50 on prompts up to 100K tokens and the fastest in Anthropic's ranking, and unlike Haiku 4.5, it's built the same way as the three above it. It has a 1M context window and a 128K output cap, uses adaptive thinking, and supports the effort parameter, defaulting to medium.

It's also the only current model whose rate depends on prompt length. Past 100K tokens, input and output rise to $0.50 and $2.50, so a routing setup that sends long-context steps to Haiku should track how many requests cross that line. It's built for high-volume, latency-sensitive tasks like classification, extraction, and routing, while the benchmarks in any Haiku vs Sonnet comparison show where it falls behind on harder work.

Claude Models Comparison

Fable 5.1, Opus 5.5, Sonnet 5.5, and Haiku 5.5 now share the same request shape, context window, and output ceiling, so the differences between them come down to price, speed, and how much reasoning each call buys.

Most of those rows now match across the lineup, and the ones that don't still change a routing decision:

• Context and output - All four models include the full 1M-token window and a 128K output ceiling, so size no longer rules any tier out. The catch is Haiku 5.5's pricing, which rises once a prompt passes 100K tokens, while the other three charge the same rate across the full window. On the Message Batches API, Opus 5.5, Sonnet 5.5, and Haiku 5.5 can also return up to 300K output tokens with a beta header.
• Thinking and effort - Adaptive thinking lets the model decide how much to think on each step, steered by an effort level. Opus 5.5 and Haiku 5.5 default to medium while Fable 5.1 and Sonnet 5.5 default to high, and thinking is always on for Fable and Opus. Lowering effort is the cheaper lever for routine steps on any tier.
• Latency - Anthropic ranks Haiku fastest and Fable slowest, though real latency depends on prompt length, output length, and effort. The ordering rarely matters for asynchronous work, but it can decide the tier for interactive steps, where TTFT (time to first token) is what users actually feel.
• Knowledge cutoff - All four models now have a reliable knowledge cutoff of June 2026, so the cutoff no longer separates the tiers, though a prompt about anything more recent still needs the source material passed in.
• Safety classifiers - Fable 5.1, Opus 5.5, and Sonnet 5.5 run classifiers that most often flag cybersecurity and biology content. In Claude Code, flagged requests on Fable 5.1 and Opus 5.5 re-run on Opus 5 or Opus 4.8 depending on the category, while Sonnet 5.5 re-runs flagged cybersecurity requests on Sonnet 5 and refuses flagged biology requests, so security and life sciences teams can't assume the top tier answers every request in those domains.

Put together, the tiers now differ mainly in how much reasoning a call gets and what it costs. The first routing question for any step is how much reasoning it needs, and the second is whether its prompts stay under the 100K tokens where Haiku 5.5 is cheapest.

Claude Models Pricing & Costs Comparison

Claude API pricing is per million tokens, with separate rates for input, output, cache reads, and batch jobs. At list price, the four current models span a hundredfold range on both input and output.

All prices are per million tokens, from Anthropic's pricing page.

List price is the easy part of the comparison. What a workload actually costs depends on how many calls a task takes on each tier, how long those calls run, and how often a cheaper model has to retry a step that a more capable one would have finished.

The tokenizer no longer shifts the math inside the lineup. Anthropic's models from 4.7 onward use a newer tokenizer that produces roughly 30% more tokens for the same text, and with Haiku 5.5 on it too, all four current models count tokens the same way. The difference only matters when comparing against an older model like Haiku 4.5 or Sonnet 4.6.

To see what routing does to the bill, take a hypothetical agent task that makes ten calls, each with 20K input tokens and 2K output tokens, and set caching aside:

The mixed setup costs about 27% of the all-Opus run, and the six Haiku calls add less than two cents between them. The saving only holds if the Sonnet and Haiku steps still produce acceptable output, though, which is what AI evaluation tools built for production measure by scoring each step on real requests.

Discounts don't change the ranking much. Batch jobs take 50% off every model through the Anthropic Message Batches API, for work that doesn't need an answer right away. Cache reads cost 2.5% of base input on Fable 5.1, 5% on Opus 5.5 and Sonnet 5.5, and 10% on Haiku 5.5, which narrows the gaps between tiers on cache-heavy agent loops and is worth modeling with the Claude prompt caching TTL math if most of a workload's input is a repeated prefix.

Older versions are priced differently from the current lineup. Sonnet 4.6 and Sonnet 4.5 still cost $3/$15, more than Sonnet 5.5, and every Opus from 4.5 through Opus 5 costs $5/$25, more than Opus 5.5, so staying on an older model rarely saves money, a point the Claude Opus vs Sonnet comparison works through version by version.

Best Claude Models by Use Case

Coding, writing, and research each mix steps that need very different amounts of reasoning. The best Claude model for each is usually a primary tier, with cheaper ones handling the routine parts.

Best Claude Model for Coding

For most coding work, Claude Opus 5.5 is the model to start with, since Anthropic lists it for long-running agentic coding. A coding agent rarely needs Opus on every call, though, whether the cheaper steps go to a smaller Claude tier or to one of the open-weight Claude Opus alternatives. Planning a change and deciding where it belongs is the expensive reasoning, while making a scoped edit, running tests, and reading files are steps that Sonnet 5.5 or Haiku 5.5 can often take.

Claude Code already splits work this way. Its opusplan setting runs Opus in plan mode and switches to Sonnet for execution, and its alias descriptions pitch sonnet for daily coding, haiku for simple tasks, and fable for the hardest and longest-running work.

Fable 5.1 pays off on root-cause investigations, outage debugging, and architecture decisions, where extra investigation before acting saves more time than it costs. That makes it a model to escalate to for a specific kind of problem rather than one to leave running on every edit.

Best Claude Model for Writing

Writing pipelines that generate text at volume, such as documentation drafts or release notes, usually belong on Claude Sonnet 5.5, since each output gets reviewed downstream and cost scales with every request. Bounded rewriting steps, like normalizing tone or trimming length, fit Haiku 5.5 at a twentieth of the rate.

Long-form analytical and technical writing is where Opus 5.5 earns its price, because the work depends on holding an argument together across a long document. Output length no longer separates the tiers, since all four can return up to 128K tokens in one response.

Knowledge cutoff is the other writing constraint. Every current model's reliable knowledge runs through June 2026, so a pipeline writing about anything more recent should pass the source material in rather than rely on what the model already knows.

Best Claude Model for Research

Research workloads are usually context-bound before they're reasoning-bound. All four current models take the full 1M-token window, so the choice comes down to how much judgment the synthesis needs, with one pricing wrinkle: Haiku 5.5 charges its higher rate on prompts past 100K tokens, while Opus 5.5 and Sonnet 5.5 stay at standard pricing across the full window.

Research agents that search, read, and revise over hours are the case Anthropic built Fable 5.1 for, and it describes the model as setting a new standard on long-running problem-solving tasks. The retrieval and extraction steps inside that agent can still sit on Sonnet 5.5 or Haiku 5.5, with Fable reserved for deciding what to look at next and what the results mean.

Life sciences research has one more constraint. Fable 5.1 and Opus 5.5 both run biology safeguards that fall back to Opus 5 on dual-use requests in areas like virology, so teams in that field may need Anthropic's Life Sciences Verification Program for access with more permissive biology safeguards.

Route, Compare, and Evaluate Claude Models

Routing each step to the cheapest tier that handles it depends on two things. Switching models has to be cheap, and you need proof that a step still works after you move it down a tier.

Respan's LLM gateway and evals cover both, so you can route, observe, and evaluate every LLM call in one platform, with the tier decision resting on scores from your own traffic.

• Browse and pick models - The model catalog lists every model on the gateway with its context limit, token pricing, and capabilities. Pick the ones you want and call them through one OpenAI-compatible endpoint to 1,000+ models, so moving a step from claude-opus-5-5 to claude-sonnet-5-5 is a config change rather than a deploy.
• Let Respan pick the model - Set the model to Respan Router, and Respan chooses the model for each request based on the task, so a step doesn't need a hand-assigned tier to get started.
• Fall back across tiers - Set a fallback chain once, at org level or per request, and traffic reroutes to the next model automatically when a provider errors or rate-limits.
• Compare models side by side - Test the same prompt on Opus 5.5, Sonnet 5.5, and Haiku 5.5 in the playground, on the same input, with parameter overrides and tools, and see which models teams actually route the most traffic and spend to on the Respan LLM leaderboard.
• Simulate real conversations - Simulations run a committed prompt version against generated multi-turn conversations with different users, goals, and interaction styles, then evaluate each conversation against its scenario's criteria. Scenarios are saved, so you can rerun the same set against a version on a cheaper Claude model and see where it breaks before it reaches production.
• Pick the model with real data - Sample production requests into a dataset, run each Claude model through the same evaluators as an experiment, and compare score distributions before deploying the winner. An evaluator can combine an LLM judge, a deterministic code check, or a human reviewer into a single score, and any row clicks straight into the trace behind it.
• Catch a tier that slips - Deploy the same evaluator on live production spans, sampled to control cost, so a step that degrades after a model update shows up as a score change instead of a user complaint.
• Version prompts per model - Commit and compare prompt versions and deploy them without shipping code, so a prompt tuned for Sonnet 5.5 can be tested against Haiku 5.5 before it replaces what's live.
• See cost by model and customer - Costs break down by model, by request, and by end customer, with soft and hard spend limits that stop a runaway experiment at a ceiling you set.

With routing and scoring in one place, each step's tier becomes a decision backed by its own score and cost. Revisiting it after the next Claude release means rerunning the experiment rather than starting the comparison over.

Frequently Asked Questions

How many Claude models are there?

Anthropic has four current, generally available Claude models, one per tier: Fable 5.1, Opus 5.5, Sonnet 5.5, and Haiku 5.5. Older versions such as Fable 5, Opus 5, Sonnet 5, and Haiku 4.5 are still available on the Claude API, and Claude Mythos 5.1 runs on the same underlying model as Fable 5.1 but is limited to Anthropic's trusted access programs.

What's the difference between the Claude models?

The four current Claude models share a 1M-token context window and a 128K output cap, so the differences come down to how much reasoning each call buys and what it costs. Fable 5.1 ($10/$50 per million tokens) is built for long-horizon agentic work, Opus 5.5 ($4/$20) is Anthropic's recommended starting point for most workloads, Sonnet 5.5 ($2/$10) fits production steps that need judgment, and Haiku 5.5 ($0.10/$0.50 up to 100K tokens) handles high-volume, bounded steps.

Is Claude a Large Language Model?

Yes. Claude is a family of large language models developed by Anthropic, and the current generally available lineup is Fable 5.1, Opus 5.5, Sonnet 5.5, and Haiku 5.5. Every current model accepts text and image input and supports tool use, and developers can reach them through the Claude API, Amazon Bedrock, Google Cloud, and Microsoft Foundry.

How to Change the Model in Claude Code

Run /model inside a session to open the model picker, or type /model opus to switch directly. By default, /model also saves your choice for new sessions, and pressing s on a row in the picker switches for the current session only. To set a model at launch, use claude --model sonnet, and for a persistent default, set the model field in your settings file or the ANTHROPIC_DEFAULT_MODEL environment variable.

The opus, sonnet, haiku, and fable aliases point to the recommended version for your provider, and opusplan runs Opus in plan mode and Sonnet for execution. Opus 5.5 is the default on Pro, Max, Team, Enterprise, and API accounts, and the 5.5 models need a recent version: v2.1.280 or later for Opus 5.5, v2.1.284 for Sonnet 5.5, and v2.1.293 for Haiku 5.5. Fable 5.1 requires Claude Code v2.1.257 or later and isn't the default on any plan, so select it explicitly with /model fable. The full list of aliases and settings is in Anthropic's Claude Code model configuration docs.