GPT-6.1 Sol vs. Claude Opus 5.5: Which AI Model Should You Choose?

Philip Moses

Oct 6

3 min read

GPT-6.1 Sol and Claude Opus 5.5 are both designed to bring advanced AI performance to real-world workloads without the cost of the highest-end models.

OpenAI positions GPT-6.1 Sol around cost-efficient agentic work, while Anthropic's Claude Opus 5.5 focuses on high performance for complex, long-running tasks.

The interesting part is that neither model wins everywhere. The better choice depends on cost, workload complexity, context size, and deployment requirements.

GPT-6.1 Sol vs Claude Opus 5.5

Feature	GPT-6.1 Sol	Claude Opus 5.5
AutomationBench	36.1%	42.5%
GDP.pdf	32.0%	28.8%
Terminal-Bench Science	57.0%	63.3%
Context window	1.05M	1M
Max output	128K	128K
Effort levels	Low–Max	Low–Max

The benchmark results show an important pattern: Opus 5.5 can reach a higher ceiling on difficult tasks, while GPT-6.1 Sol focuses heavily on cost efficiency.

GPT-6.1 Sol: Built for Cost-Efficient Agents

GPT-6.1 Sol is OpenAI's mid-tier reasoning model in the GPT-6 family.

Its biggest advantage is economics.

For standard usage, GPT-6.1 Sol costs approximately half as much as Claude Opus 5.5.

It is particularly attractive for:

High-volume AI agents
Document analysis
Coding workflows
Repeated-context applications
Business automation

For companies running thousands of AI tasks, the difference in cost can become significant.

Claude Opus 5.5: Higher Ceiling for Difficult Tasks

Claude Opus 5.5 is Anthropic's flagship model in the Claude 5.5 family.

It is designed for demanding workloads such as:

Long-running coding agents
Complex research
Business automation
Scientific workflows
Computer-use tasks

At maximum effort, Opus 5.5 can outperform GPT-6.1 Sol on some of the harder benchmarks.

The trade-off is cost.

Pricing Comparison

Per 1M Tokens	GPT-6.1 Sol	Claude Opus 5.5
Input	$2	$4
Output	$10	$20
Cached input	$0.10	$0.20
Cache write	$2.50	$5

For normal-sized prompts, GPT-6.1 Sol is essentially 50% cheaper across the standard rates.

However, there is an important exception.

GPT-6.1 Sol applies a higher pricing tier when input exceeds 272K tokens. For workloads that regularly process extremely large contexts, the cost advantage becomes much smaller.

Which Performs Better?

The answer depends on the task.

Business Automation

At medium effort, GPT-6.1 Sol offers strong performance at a significantly lower cost.

At maximum effort, however, Opus 5.5 reaches a higher AutomationBench score.

Winner: GPT-6.1 Sol for cost efficiency; Opus 5.5 for maximum performance.

Coding

Both models are strong coding agents.

GPT-6.1 Sol performs well on long-horizon software engineering tasks, while Opus 5.5 has strong results on Terminal-Bench and other agentic coding evaluations.

For most development teams, the difference may come down to cost and workflow integration rather than raw capability.

Computer Use

The published results are not directly comparable because the two companies tested different versions of OSWorld.

So there is no clear winner yet.

A Real-World Coding Test

A practical test comparing the two models used the same prompt to build an appointment scheduler for a healthcare clinic.

Both models successfully handled:

Appointment conflicts
Clinician scheduling
Room conflicts
Editing and deleting appointments
Data persistence
Reloading the application

Both received 5/5 for specification and conflict handling.

The main difference was cost.

GPT-6.1 Sol: $0.27
Claude Opus 5.5: $1.11

For this particular task, GPT-6.1 Sol delivered a similar result at roughly one-quarter of the cost.

When Should You Choose Each?

Choose GPT-6.1 Sol if:

You run AI agents at high volume
Cost per task is important
You work heavily with documents
You frequently reuse context
Your team already uses OpenAI's ecosystem
Your prompts generally stay below the long-context pricing threshold

Choose Claude Opus 5.5 if:

Maximum performance matters more than cost
You run difficult, long-running agent tasks
Your prompts regularly exceed 272K tokens
You use Cursor, Bedrock, or Vertex AI
You want Anthropic's safety-oriented routing for certain sensitive workloads

Which One Is Better?

There is no universal winner.

GPT-6.1 Sol is the better value. It delivers strong performance at significantly lower standard token prices, making it attractive for high-volume agents and business automation.

Claude Opus 5.5 is the stronger choice when maximum capability matters. Its higher-effort performance can make the additional cost worthwhile for complex workflows where a failed run is expensive.

The decision should therefore be based on cost per successful task, not simply the benchmark score.

Conclusion

GPT-6.1 Sol and Claude Opus 5.5 represent two different approaches to efficient frontier AI.

GPT-6.1 Sol focuses on strong performance at lower cost, while Opus 5.5 focuses on pushing performance higher on difficult workloads.

For everyday agents and high-volume automation, GPT-6.1 Sol is the more economical choice. For complex tasks where maximum success matters, Opus 5.5 may justify its higher price.

The best model is not always the one with the highest benchmark score—it is the one that delivers the best results for your actual workload and budget.