Which Claude model is best depends on what you want to use it for. Anthropic recommends Opus 5.5 as the starting point for most use cases. Sonnet 5.5 is the faster, more economical choice for everyday writing and for getting more tasks done within your limits. For fast automation at volume, choose Haiku 5.5.
The gap between Opus and Sonnet is widest on the heaviest reasoning tasks, where careful judgement matters. Opus 5.5 was released on 22 September 2026, Sonnet 5.5 followed on 28 September and Haiku 5.5 on 7 October.
These models belong to the wider family of Claude models from Anthropic, and that article sets out the technical specifications for each model and version. This article focuses on the choice itself: which model suits which type of work.
| Task | Best Claude model | Why |
|---|---|---|
| Everyday writing and analysis | Sonnet 5.5 | Faster and more economical than Opus 5.5 for well-defined daily work |
| Long documents | Sonnet 5.5 | 1 million tokens of context as standard, with no surcharge |
| Complex reasoning and strategy | Opus 5.5 | Anthropic’s recommended starting point, strongest where careful judgement counts |
| Coding tasks | Sonnet 5.5, Opus 5.5 for demanding judgement work | 70.6% on Terminal-Bench 4.0 for Sonnet 5.5 and 66.4% for Opus 5.5, according to Anthropic |
| Automated workflows at volume | Haiku 5.5 | Fastest response time and lowest cost per token |
| Free use via claude.ai | Sonnet 5.5 | Available on the Free plan, with usage limits |
Claude Opus vs Sonnet vs Haiku: what is the difference?
Opus, Sonnet and Haiku differ in reasoning depth, speed and price. Opus 5.5 is the most capable standard model, built for work that calls for careful judgement. Sonnet 5.5 is the fast all-rounder for well-defined daily tasks, and Haiku 5.5 is the lightest model, for work at volume.
On the API, Opus 5.5 costs $4 input and $20 output per million tokens, Sonnet 5.5 $2 and $10, and Haiku 5.5 $0.10 and $0.50 for prompts up to 100,000 tokens. All three work with a context window of one million tokens.
In this generation the gap between Sonnet and Opus is small. You used to reach for Opus as soon as a document got long, but that argument no longer holds: the reason to switch is now reasoning depth, not capacity.
Which Claude model is best for most professionals?
For most professionals, Claude Opus 5.5 is the model to start with. Anthropic recommends Opus 5.5 as the starting point for most use cases and positions Sonnet 5.5 as the faster, cheaper option for well-defined daily tasks. Sonnet strikes a strong balance between quality, speed and cost, and handles reports, emails, analyses and client communication without long waits for an answer.
The choice between the two comes down to the type of task. Opus 5.5 gives the most thorough judgement, but on the API it costs twice as much as Sonnet 5.5 and takes longer per answer. If you mostly set short, clearly defined tasks, or lots of tasks in a row, Sonnet is the more economical choice within your limits. If your work often involves weighing up options and reasoning, keep Opus as your default.
In my own work with Claude, Opus is now the default for most content and analysis tasks. The output is usable straight away without extensive editing, and Opus follows instructions closely, which is most noticeable in multi-step tasks where tone, structure and length have to be exactly right.
In the Claude apps, Sonnet 5.5 runs at medium effort by default, which gives faster answers and uses fewer tokens. If a task needs more thinking, turn the effort up.
Which Claude model is best for writing?
For writing tasks, Claude Sonnet 5.5 is the best Claude model. According to Anthropic it writes more clearly than the previous generation. It produces output that is consistent in tone and structure, and it suits business communication: emails, reports, proposals and marketing content.
Sonnet adapts its writing style to the instructions you give it. Tell it who the text is for and what tone you want, and the model produces a first draft you can adjust to your own style straight away. A side effect of following instructions this closely is that the output sounds less recognisably AI-generated, provided you set up the prompt well.
For creative writing where originality and a stronger storyline come first, Opus performs better. The model takes longer to build an answer, but the output has more substance on open creative tasks.
When I moved from Opus 4.6 to 4.7, I noticed the answers became longer and less sharp, with more explanation and nuance than strictly necessary. For business writing where brevity counts, Sonnet therefore usually remains the better choice, even though Opus is technically capable.
Which Claude model is best for coding?
For programming, Claude Sonnet 5.5 is the best Claude model for most tasks, with Opus 5.5 for work where the model has to make difficult judgement calls on its own. For writing standard functions, fixing bugs and explaining existing codebases, Sonnet is fast and accurate.
On Terminal-Bench 4.0, the benchmark that measures whether a model can complete complex terminal tasks on its own, Sonnet 5.5 scores 70.6%, according to Anthropic. Opus 5.5 reaches 66.4%, against 57.9% for GPT-6 Astra, OpenAI’s flagship.
That does not make Opus redundant. Anthropic positions Sonnet 5.5 for well-defined tasks and Opus 5.5 for complex work that calls for careful judgement.
In the Python integrations I built with the Claude API, most workflows start with Sonnet and only switch to Opus when a specific problem needs more reasoning depth. With the current price difference, Opus costing twice as much, that order pays for itself. In the AI Automation Course with Claude you make that trade-off for each step yourself, with or without code.
One pitfall of coding with language models remains: they tend to generate functions, hooks or CSS properties that look convincing but do not exist and are not documented anywhere. This happens less often with Claude than with other models, but it never disappears completely. Always test generated code before you put it into production.
Haiku is less suited to coding, unless the task is simple and repetitive, such as generating standard boilerplate or formatting data.
Which Claude model is best for document analysis?
For analysing long documents, Claude Sonnet 5.5 is now the best model, and that is a change from earlier generations. Since the release of Sonnet 5 in June 2026, Sonnet has worked with a context window of one million tokens as standard, with no beta setting and no surcharge for long requests.
This means capacity is no longer a reason to reach for Opus. A request of 900,000 tokens costs the same per token as a request of 9,000, on both Sonnet 5.5 and Opus 5.5.
Do check where you actually get that window. For the claude.ai interface on the paid plans, Anthropic lists a context window of one million tokens for the current models, including Sonnet 5.5 and Opus 5.5; older models get 500,000 or 200,000 tokens. Anthropic does not state a window for the Free plan. Via the Claude API, the full million is available on Sonnet 5.5 and Opus 5.5.
Opus 5.5 remains the better choice once the analysis itself is demanding: comparing several sections for subtle contradictions, or drawing conclusions that reason across passages far apart in the text. The distinction lies in reasoning depth, not document length.
Which Claude model is best for automation?
For automated workflows and high volumes of simple tasks, the best model is Claude Haiku 5.5, which Anthropic released on 7 October 2026. Haiku is the fastest of all Claude models and is the most cost-efficient for tasks that do not require complex reasoning.
Examples include classifying incoming emails, extracting data from forms and tagging content. For tasks like these, Haiku delivers usable output without the cost and processing time of Sonnet or Opus.
In workflows at volume, every fraction of a cent per token counts. Haiku 5.5 costs from $0.10 per million input tokens, against $4 for Opus 5.5, and handles simple tasks in a fraction of the time.
For tasks that pull structure out of input, such as turning free text into JSON, Haiku is often enough even where you would instinctively reach for Sonnet. Combine that with the Batch API for work that does not need to come back immediately, and you halve the cost again.
What is the best free Claude model?
In the free version of Claude you chat with Sonnet 5.5, and you can also choose the lighter Haiku 5.5. For most tasks that is a strong starting point to find out what Claude can do for your work.
Having Sonnet 5.5 on the Free plan is a real improvement. On GDPval-AA, a benchmark for professional knowledge work, the model scores two points below Opus 5.5, the most capable standard model on the paid plans, according to Anthropic.
The free version has usage limits: a limited number of messages per rolling five-hour window, depending on how busy the platform is and how long your conversations are. That is plenty for occasional use, but for daily work you will run into the limits.
To use Opus 5.5 you need a paid subscription.
Which Claude model suits your task?
Choose your task and where you use Claude. You will see which model fits that task best and what your plan allows.
Which Claude model should you choose?
Which Claude model you should choose depends on the type of work you do most. Start with Opus 5.5, the starting point Anthropic recommends for most use cases. Choose Sonnet 5.5 if you mainly do well-defined daily work or run lots of tasks at volume: it is faster, costs half as much on the API and goes further within your limits. Opus 5.5 is not included in the Free plan; there you start with Sonnet 5.5.
For organisations that do not want to leave this choice to each employee, model choice belongs in an AI policy for the whole organisation, which sets out the default model for each role.
If you work with Sonnet 5.5 by default, switch to Opus 5.5 when a specific task needs more reasoning depth, such as complex strategic questions or demanding coding tasks you want to hand over to the model with confidence. Since Sonnet 5, document length is no longer a reason to switch.
Use Haiku 5.5 specifically for automated workflows where speed and volume come first. For the very heaviest tasks there is also Claude Fable 5.1, which costs two and a half times the Opus 5.5 rate and is intended for agents that keep working on their own for days. Since September 2026 the effective price has been lower when you reuse a lot of context, because reading from the cache on that model costs only 0.025 times the input rate.
For regulated work, Fable comes with one caveat. By default, Fable 5.1 requires a thirty-day retention period for safety monitoring. According to Anthropic, eligible customers can use Fable 5.1 with zero data retention until Enterprise Frontier Safeguards are rolled out (as of 13 October 2026). If you work with data for which zero retention is contractually required, check with Anthropic first whether your organisation is eligible.
A new model version is not automatically a better version for your work. You only notice the difference when you use the tool every day and retest your existing workflows on the new version.
When I moved from Opus 4.6 to 4.7, for example, I noticed the model became more expansive and wordier, with more explanation than strictly necessary. There is also a change that affects your bill: models from Claude 4.7 onwards use a new tokenizer that produces about 30% more tokens for the same text. So retest your own workflows before you switch an existing integration over.
For heavy analytical work, the environment matters as well as the model, because the Claude Science research environment is built for that type of task.
Want to learn how to use the Claude models effectively in your daily work? In the Claude Course you build your own way of working with repeatable workflows and checkpoints, where you link your choice of model to your type of work from the start.
Frequently asked questions about the best Claude model
Beyond the question of which Claude model is best for your task, settings and plans affect what you get in practice.
What does the effort level do in Claude?
The effort level in Claude determines how much reasoning the model puts into an answer, from Low to Max, with Extra high as an additional step on the current models, including Opus 5.5, Sonnet 5.5 and Haiku 5.5. A higher level gives a more thorough answer but takes more time and tokens, so you reach your usage limit sooner. You can change the level at any point in a conversation, and the change applies from Claude’s next answer.
Can you use Claude Fable in claude.ai?
You can only use Claude Fable in claude.ai with a paid plan. On Pro you pay for Fable separately with usage credits at API rates, on Max, Fable is included up to half of your weekly limit, and Ultra has a separate weekly limit for Fable. On Team this applies only to Premium seats, and the Free plan does not offer Fable.
Can all Claude models read images?
Yes. According to Anthropic’s model overview, all current Claude models, from Haiku 5.5 to Fable 5.1, accept images as input alongside text. So that capability does not affect your choice between the models. You can give a screenshot or photo to Haiku 5.5 too, which makes it the cheapest model for reading images at volume.
