Opus 5.5 vs Sonnet 5.5 vs GPT-6.1 Sol: which to use

Start with Claude Sonnet 5.5 for well-defined everyday work, consider Claude Opus 5.5 for complex tasks that need sustained judgement, and try GPT-6.1 Sol if your workflow belongs in ChatGPT Work or Codex. That is a starting point based on the providers' descriptions, not a claim that one wins every task. For buyers in Ethiopia, checking where the model is available matters as much as choosing it.

GPT-6.1 Sol is not available in regular ChatGPT conversations. OpenAI's current help page lists it in Work and Codex, with access depending on your plan, workspace settings and rollout. Do not buy a subscription expecting a Sol button in ordinary Chat.

Updated and sources checked: 12 October 2026. This article uses official announcements, model pages and access documentation. It was prepared with AI assistance; we have not run an independent head-to-head benchmark. Recommendations below are practical ways to choose a first test, not measured performance guarantees.

Claude Opus 5.5: when the task is hard to define

Anthropic released Claude Opus 5.5 on 22 September 2026. It positions the model for long-running coding, agents and professional work: tasks where the model needs to plan, keep track of constraints and make decisions over many steps. See Anthropic's Opus 5.5 announcement.

A useful example is an audit of an unfamiliar codebase, or a research brief that must reconcile several documents with conflicting conclusions. Those jobs need more than a quick answer. Opus is the first model we would test for that kind of open-ended work, based on Anthropic's positioning; you still need to inspect its reasoning, citations and completed changes.

Anthropic says Opus 5.5 generates output more than 30% faster than Opus 5 and costs about 40% less for typical token-billed workloads. That is not a 40% discount on Claude Pro or Max. It is a provider claim about the cost of running tasks, and your task may differ.

For chat users, Anthropic lists Opus 5.5 on Pro, Max, Team and Enterprise. A paid plan provides access under its usage rules; it does not mean unlimited Opus work.

Claude Sonnet 5.5: the everyday starting point

Sonnet 5.5 arrived on 28 September 2026. Anthropic calls it a faster, lower-cost complement to Opus 5.5, strongest at well-scoped tasks across coding and knowledge work. Its Sonnet 5.5 announcement highlights clearer writing, documents, slides, spreadsheets and design iteration.

Think of a contained bug fix with a known failing test, an edit to a two-page proposal, or a presentation built from an outline you already trust. Start with Sonnet when you can explain what a correct result should look like. Move to Opus if the task needs broader investigation or you repeatedly have to repair Sonnet's answer.

Anthropic reports over 30% faster generation than Sonnet 5 and up to 30% lower cost on typical token-billed work. Again, these are its comparisons against the previous Sonnet, not a speed guarantee on your connection or a subscription-price reduction.

Anthropic says anyone can chat using Sonnet 5.5 on Claude.ai. If free access handles your work and its limits are enough, a new model release alone is not a reason to pay. Opus and Sonnet are model choices, not two separate subscriptions you must buy.

GPT-6.1 Sol: Work and Codex, not ordinary Chat

OpenAI introduced GPT-6.1 Sol on 29 September 2026, targeting complex coding, computer use and professional work. It describes the model as approaching GPT-6 Astra's capability on its evaluations at lower API cost. See OpenAI's GPT-6.1 Sol announcement.

The app you use is part of the decision:

• Chat is ChatGPT's conversational experience. Sol is not currently offered there.
• Work is for longer, multi-step jobs such as research, reports, documents, spreadsheets and presentations.
• Codex is for software development: working with repositories, debugging, tests and technical tools.

The launch announcement names Plus, Pro, Business, Enterprise and Edu. The current Work and Codex help page adds an important qualification: GPT-6.1 Sol is rolling out for eligible paid plans, and the options you see depend on your account and workspace. Work and Codex also have usage allowances separate from Chat. Check the actual model picker and plan terms rather than treating the launch list as a guarantee for every account.

Sol is worth testing if you already use Work for finished deliverables or Codex for code. Paying for a different brand is less useful than checking whether the model can reach the files and tools your job needs, with permissions you are comfortable granting.

Which would we try for your work?

Writing, study and editing

Try Sonnet first for an outline, a draft or a focused rewrite. Consider Opus for a difficult argument or a synthesis across several long sources. If you want a completed report or spreadsheet in ChatGPT, test Sol in Work where available. None of these choices makes a citation real: open the original source before submitting academic or professional work.

Coding

Start with Sonnet for a bounded change; try Opus for a cross-cutting migration or investigation. Sol in Codex is another candidate for repository work. These are sensible test routes, not an overall coding ranking. Run the same tests, review the diff and check that the task is finished, rather than judging how convincing the explanation sounds.

Business documents and analysis

Use a sample of the work you actually produce: a quotation comparison, a report or a spreadsheet. Check source figures, formulas and exported files. A model's ability to write a polished paragraph says little about whether it has calculated the totals correctly.

Amharic and mixed-language work

We have not established a winner for Amharic. Test the same real prompts on the models you can access, including your preferred mix of Amharic and English. Have a fluent reader check meaning, names and tone. A general benchmark is not evidence that a model uses your terminology correctly.

API prices are not monthly subscription prices

Developers are charged for tokens: pieces of text supplied to the model and generated in its response. The standard API input/output rates in the official sources checked on 12 October 2026 are:

• Opus 5.5: $4 per million input tokens; $20 per million output tokens.
• Sonnet 5.5: $2 per million input tokens; $10 per million output tokens.
• GPT-6.1 Sol: $2 per million input tokens; $10 per million output tokens.

Sonnet and Sol therefore have the same listed standard input/output token rates, but that does not make their total task costs identical. Caching, long-context rates, tools, retries and speed settings can change the bill. Compare completed jobs, not just the price per token. API charges are separate from Claude and ChatGPT subscriptions, and published API context limits are not promises about what a chat plan permits.

What to check before paying in Ethiopia

1. Name the task and the app. Do you need ordinary chat, document work or a coding agent? Ask for the exact model in that experience, not just “the latest AI”.
2. Check access and limits. Confirm the plan, model availability, rollout and any workspace permissions. A higher subscription tier is not automatically necessary for your task.
3. Test one representative job. Use non-sensitive sample data. Record errors, corrections and whether the output is usable.
4. Confirm the birr price and renewal terms. Compare the current offer, not a dollar token rate or an old screenshot.

Bezuale provides independent local-payment and setup assistance. The Claude Pro Ethiopia page and ChatGPT Plus Ethiopia page show the current offers; our ChatGPT payment guide explains the birr checkout. Those pages sell subscriptions, not an unconditional promise of access to every model. We are not affiliated with Anthropic or OpenAI.

If your current free or paid assistant already does the job well, keep it. If a particular model is essential, confirm that requirement before paying. Ask about the plan and current access through @itsabelb.

Questions people ask

Is Sonnet 5.5 better than Opus 5.5?

Not universally. Anthropic positions Sonnet 5.5 for faster, well-scoped everyday tasks and Opus 5.5 for complex, open-ended work. A result on one benchmark does not settle your workflow; test a real task with the same source material and requirements.

Can I use GPT-6.1 Sol in normal ChatGPT chat?

No, according to OpenAI's Work and Codex help page checked on 12 October 2026. Sol is offered in Work and Codex, with access depending on your plan, workspace and rollout. Check the model picker in the experience you intend to use.

Do I need separate subscriptions for Opus and Sonnet?

No. Opus and Sonnet are model families within Claude, not separate subscription products. Anthropic lists Opus 5.5 on Pro, Max, Team and Enterprise, and says anyone can chat using Sonnet 5.5. Usage limits still apply.

Which is cheapest?

At the standard API input/output rates checked on 12 October 2026, Sonnet 5.5 and GPT-6.1 Sol both list $2/$10 per million tokens, compared with Opus 5.5's $4/$20. Those are not monthly subscription prices, and they do not establish which costs least to finish your task.

Sources and how we compared them

We checked the following official sources on 12 October 2026. Provider descriptions informed the suggested starting points; we have not combined different benchmark versions or effort settings into a leaderboard.

• Anthropic: Claude Opus 5.5 announcement and Opus access and pricing.
• Anthropic: Claude Sonnet 5.5 announcement and Sonnet access and pricing.
• OpenAI: introducing GPT-6.1 Sol.
• OpenAI Help Centre: ChatGPT Work and Codex.

Written by the Bezuale Solutions team in Addis Ababa. Questions? Message us on Telegram.