OpenAI vs Anthropic 2026:
GPT-6.1 Sol vs Claude Sonnet 5.5 — Price & Features
How OpenAI's GPT-6.1 Sol compares with Anthropic's Claude Sonnet 5.5 — the two mainstream production models — on price, caching, context and features, with cost estimates for common apps. Last verified: 2026-10-01.
OpenAI vs Anthropic: Quick Comparison
| Feature | OpenAI (GPT-6.1 Sol) | Anthropic (Claude Sonnet 5.5) |
|---|---|---|
| Input price (1M tokens) | $2.00 | $2.00 |
| Output price (1M tokens) | $10.00 | $10.00 |
| Cached input (1M tokens) | $0.10 (95% off) | $0.20 (90% off) |
| Context window | 1.05M tokens | 1M tokens |
| Long-prompt surcharge | 2× input, 1.5× output above 272K | Single rate in Anthropic's price list |
| Batch API discount | 50% | 50% |
| Vision (image input) | ✅ | ✅ |
| Tool/function calling | ✅ | ✅ |
At list price the two mainstream models are identical. The differences show up around them: OpenAI's budget model is far cheaper, Anthropic's premium model is far cheaper, and caching and long-prompt rules shift the totals for specific workloads.
The Full Lineups
| Tier | OpenAI | Anthropic |
|---|---|---|
| Budget | GPT-6 Luna — $0.10 / $0.50 | Claude Haiku 4.5 — $1 / $5 |
| Mainstream | GPT-6.1 Sol — $2 / $10 | Claude Sonnet 5.5 — $2 / $10 |
| Premium | GPT-6 Astra — $10 / $50 | Claude Opus 5.5 — $4 / $20 |
| Frontier | GPT-6 Astra — $10 / $50 | Claude Fable 5.1 — $10 / $50 |
When to Choose OpenAI
- High-volume simple tasks: GPT-6 Luna at $0.10/$0.50 is ten times cheaper than Claude Haiku 4.5.
- Ecosystem & integrations: OpenAI has the widest third-party support — LangChain, LlamaIndex and many libraries default to it.
- Mid-tier caching: GPT-6.1 Sol's cached input ($0.10/M) is half the price of Sonnet 5.5's.
- Platform features: Assistants-style tooling, fine-tuning options and Azure OpenAI deployment.
When to Choose Anthropic Claude
- Premium quality on a budget: Claude Opus 5.5 costs 60% less than GPT-6 Astra.
- Very long prompts: Claude Sonnet, Opus and Fable bill their whole 1M-token window at one rate, while GPT-6 charges more above 272K tokens.
- Long-running agents: Anthropic focuses its lineup on coding and agentic work, with Sonnet 5.5 as the everyday default.
- Safety-sensitive applications: Anthropic emphasises predictable behaviour and declines unsafe requests with explicit refusal signals that apps can handle.
Cost Comparison for Common Apps
Verdict: Which Should You Use in 2026?
Use OpenAI for high-volume, simple workloads (GPT-6 Luna is the cheapest model either company sells) and when you depend on the OpenAI ecosystem.
Use Anthropic Claude when you need premium quality — Opus 5.5 undercuts GPT-6 Astra by 60% — or when you regularly send very long prompts.
In the middle, GPT-6.1 Sol and Claude Sonnet 5.5 cost the same, so choose on quality for your own tasks. Many production systems use both providers and route each task to the model that handles it best.
Compare OpenAI vs Claude Costs for Your Usage
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