Which Claude Model Should You Use in 2026? Opus vs Sonnet vs Haiku vs Fable

Anthropic's Claude lineup is no longer a single model with a slider. In 2026 there are three models you can use today, each tuned for a different point on the speed-cost-capability curve: Haiku, Sonnet, and Opus. A fourth model, Fable 5, briefly joined them as the frontier option before it was suspended (more on that below). If you are calling Claude through the API, building an app, or just trying to understand what powers a given plan, the question "which Claude model should I use" has a real answer, and it depends almost entirely on the task in front of you.

This guide compares the Claude models head to head and gives you a simple way to choose. If you are brand new to Claude, our free Claude for Beginners course is the fastest way to get comfortable before you start picking models.

A quick note on scope: this post is about the models, not the consumer subscription plans. If your real question is "which Claude plan should I buy" (free vs Pro vs Max), head to our free vs Pro vs Max comparison instead. Here, we focus on choosing the right model for a task.

The Claude Model Lineup at a Glance

Here is the full lineup, from most cost-effective to most capable. The prices below are API list prices per million tokens as of publication, so treat them as a snapshot rather than a permanent quote. The relative positioning is what matters most.

Model	API model ID	Context window	Max output	Input / output (per 1M tokens)	Status / best for
Claude Haiku 4.5	claude-haiku-4-5	200K	64K	$1 / $5	Available. Fast, cheap, high-volume simple tasks
Claude Sonnet 4.6	claude-sonnet-4-6	1M	64K	$3 / $15	Available. The balanced everyday workhorse
Claude Opus 4.8	claude-opus-4-8	1M	128K	$5 / $25	Available. Hardest reasoning, deep coding, long-horizon agents
Claude Fable 5	claude-fable-5	1M	128K	$10 / $50	Suspended / currently unavailable (as of publication)

A few things stand out. Among the models you can use today, Sonnet and Opus share a 1M-token context window, which is large enough to hold an entire codebase or a stack of long documents at once. Haiku trades that down to a still-generous 200K-token window in exchange for being the fastest and cheapest option. Fable 5 sat above Opus as the frontier option at $10 / $50 per million tokens, but it is currently suspended and not selectable (see the Fable 5 section below). For the practical "which model should I use" decision, the three live models are Haiku, Sonnet, and Opus, in a deliberate climb of both capability and price.

Claude Haiku 4.5: Fast and Cheap

Haiku is the model you reach for when you need speed and volume more than raw intelligence. It is the most cost-effective option in the lineup, and it is genuinely fast, which makes it ideal for tasks you run thousands of times: classifying support tickets, extracting fields from documents, tagging content, routing requests, or powering an autocomplete-style feature.

You should not use Haiku for tasks that need deep reasoning, careful multi-step planning, or the kind of nuanced writing where small mistakes compound. That is what the bigger models are for. But for the long tail of simple, repetitive work, Haiku does the job at a fraction of the cost, and its 200K-token context window is more than enough for most of these jobs.

Rule of thumb: if the task is simple and you are going to run it a lot, start with Haiku.

Claude Sonnet 4.6: The Everyday Default

Sonnet is the model most people should default to. It offers the best balance of speed and intelligence in the lineup, which is exactly what you want for the bulk of real work: writing and editing, summarizing long documents, answering questions, drafting code, building chatbots, and handling general-purpose tasks where you want strong results without paying flagship prices.

Sonnet also carries the full 1M-token context window, so you can feed it large inputs without splitting them up. For day-to-day coding, it is a strong default, handling most feature work, bug fixes, and code explanations comfortably.

Rule of thumb: when you are not sure which model to pick, pick Sonnet. It is the workhorse, and it is right far more often than it is wrong.

Claude Opus 4.8: The Flagship for Hard Problems

Opus is the flagship, and with Fable 5 suspended it is the most capable Claude model you can actually use right now. It is where you go when the task is genuinely hard. Anthropic positions it for state-of-the-art long-horizon agentic work, deep coding, knowledge work, and memory: the kind of tasks that run for many steps, span many files, or require the model to hold a complex goal in mind and pursue it autonomously.

Concrete cases where Opus earns its higher price over Sonnet:

• Deep, multi-file code refactors where the model has to understand a whole system before it changes anything.
• Long-horizon agentic loops that string together many tool calls and decisions toward one goal.
• Hard reasoning and analysis where getting the answer right matters more than getting it cheap.
• Knowledge work that benefits from the model planning carefully and verifying its own output.

With a 1M-token context window and a higher max output ceiling than Sonnet, Opus has the room to take on big inputs and produce substantial results. Want to get more out of it on tasks like these? Our free Prompt Engineering course teaches the techniques that separate good prompts from great ones.

Rule of thumb: reach for Opus when Sonnet starts to struggle with the complexity, depth, or length of the task.

Claude Fable 5: Launched, Then Suspended

Fable 5 was Anthropic's most capable model, built for the most demanding reasoning and long-horizon agentic work. It sat above the Opus tier at $10 / $50 per million tokens (input / output), with a 1M-token context window and a 128K max output. It launched on June 9, 2026 as the new frontier option.

Then, on June 12, 2026, Anthropic suspended Fable 5 following a US government directive issued under national-security and export-control authority. The same action also suspended its sibling model, Mythos 5. As of publication, both models are unavailable on the Claude API, the Claude apps, and the major cloud platforms. Anthropic has said it believes the situation is a misunderstanding and is working to restore access, but there is no confirmed return date, so its availability is uncertain.

The practical takeaway is simple: you cannot select Fable 5 today, and you should not design a workflow around it until access is restored. The other three models, Haiku 4.5, Sonnet 4.6, and Opus 4.8, are unaffected and continue to work normally. With Fable suspended, Opus 4.8 is the most capable Claude model you can use right now.

For the full story and the latest status on the suspension, see our Claude Fable 5 suspended explainer.

How to Choose: A Simple Decision Guide

Strip away the names and the decision comes down to matching the task to the right tier. With Fable 5 suspended, you are choosing among three live models:

• Simple, cheap, high-volume task? Use Haiku 4.5.
• Balanced everyday work (writing, summarizing, most coding, chatbots)? Use Sonnet 4.6 as your default.
• Hardest reasoning, deep multi-file coding, long-horizon agents? Step up to Opus 4.8, the most capable Claude model available today.

A practical pattern many teams use: start with Sonnet for almost everything, drop down to Haiku for the simple high-volume parts of your workload, and step up to Opus only for the specific tasks that need it. That way you are paying for capability exactly where it earns its keep, and not a token more.

If you are also weighing Claude against other tools, our Claude vs ChatGPT vs Gemini comparison covers the broader picture, and if you want the equivalent breakdown for OpenAI, see which ChatGPT model to use.

A Note on Pricing and Plans

Two reminders before you commit. First, the dollar figures in the table are API list prices as of publication, and model pricing can change, so always confirm the current numbers on Anthropic's pricing page before you build a cost model around them. The relative ordering (Haiku cheapest, Fable most expensive) is the durable takeaway.

Second, if you access Claude through a consumer subscription rather than the API, the "which model" question is wrapped up with "which plan." The plans determine which models you can reach and how much you can use them. For that side of the decision, our free vs Pro vs Max comparison is the place to go. This guide stays focused on the models themselves.

Key Takeaways

• Three Claude models are available to use today: Haiku 4.5 (fast and cheap), Sonnet 4.6 (the balanced default), and Opus 4.8 (the flagship for hard problems).
• Fable 5 is currently suspended. It launched June 9, 2026 and was suspended on June 12, 2026 under a US government directive (alongside Mythos 5); as of publication it is unavailable on the API, apps, and cloud platforms, and its return is uncertain.
• Match the model to the task: simple and high-volume goes to Haiku, everyday work to Sonnet, and hard or long-horizon work to Opus, the most capable Claude model you can use right now.
• Sonnet is the right default for most people; escalate to Opus only when the task demands it.
• Sonnet and Opus both have a 1M-token context window; Haiku has 200K.
• Prices shown are API list prices as of publication and can change, so verify before building a cost model.

Ready to put this into practice? Start with our free Claude for Beginners course to get fluent with Claude, then sharpen your results with Prompt Engineering. Both are free and come with a shareable certificate.