text model comparison
Claude Opus 5.5 vs GPT-6 Astra
Claude Opus 5.5 and GPT-6 Astra are both current text models, from Anthropic and OpenAI. Claude Opus 5.5 is 60% cheaper per 1M input tokens than GPT-6 Astra, $4 vs $10. On Arena Text, Claude Opus 5.5 scores 1507 Elo and GPT-6 Astra 1475 Elo (Arena, measured October 8, 2026). GPT-6 Astra has the larger context window, 1,050,000 vs 1,000,000 tokens.
Data verified October 13, 2026 · Dataset 2026-10-13
Side by side
Prices in effect today, compared at the same tier wherever both list one. The better value in each row is highlighted.
| Fact | Claude Opus 5.5 | GPT-6 Astra |
|---|---|---|
| Price per 1M input tokens | $4 (better) | $10 |
| Price per 1M output tokens | $20 (better) | $50 |
| Arena Text | 1507 Elo (#2 of 49) (better) | 1475 Elo (#21 of 49) |
| GPQA Diamond | 90.6% (#24 of 40) | 95.8% (#1 of 40) (better) |
| FrontierMath Tiers 1-3 (v2) | 91.2% (#3 of 40) | 93.7% (#1 of 40) (better) |
| SimpleQA Verified | 72.2% (#4 of 36) | 75.6% (#1 of 36) (better) |
| Provider | Anthropic | OpenAI |
| Release date | September 22, 2026 | September 3, 2026 |
| Access | API only | API only |
| Context window | 1,000,000 tokens | 1,050,000 tokens |
| Max output | 128,000 tokens | 128,000 tokens |
| Input | text, image | text, image |
| Output | text | text |
What each costs
Example workloads at each provider's listed rates, then every other rate either one lists. The cheaper figure in each row is highlighted.
| Workload or rate | Claude Opus 5.5 | GPT-6 Astra |
|---|---|---|
| 10M input and 2M output tokens | $80 (better) | $200 |
| The same, with 9M of the input tokens cached | $45.80 (better) | $119 |
| The same, through the batch API | $40 | Not listed |
| Other listed rates | ||
| 1M input tokens, cached | $0.20 (better) | $1 |
| 1M input tokens, 5-minute cache write | $5 | Not listed |
| 1M input tokens, 1-hour cache write | $8 | Not listed |
| 1M input tokens, batch | $2 | Not listed |
| 1M output tokens, batch | $10 | Not listed |
When to choose each
Claude Opus 5.5
Where it leads
- Lower input and output prices, $4 and $20 vs $10 and $50 per 1M tokens
- Higher Arena Text score, 1507 Elo vs 1475 Elo
- Cheaper cached input, $0.20 vs $1 per 1M tokens
- Batch pricing, $2 input and $10 output per 1M tokens
Best for
- Long-running agentic coding and knowledge work as the general-purpose default
- Cache-heavy agent loops where the 0.05x read multiplier compounds
Watch out for
- The API effort default is medium here, not high as on Claude Fable 5.1 and Claude Sonnet 5.5, so a like-for-like comparison has to set effort explicitly
- The 4.7-generation tokenizer produces roughly 30% more tokens for the same text than Claude Sonnet 4.6 and earlier, so per-token rates do not compare directly across generations
GPT-6 Astra
Where it leads
- Higher GPQA Diamond score, 95.8% vs 90.6%
- Higher FrontierMath Tiers 1-3 (v2) score, 93.7% vs 91.2%
- Higher SimpleQA Verified score, 75.6% vs 72.2%
- Larger context window 1,050,000 vs 1,000,000 tokens
Best for
- Frontier reasoning and agentic evaluations where deep-context retrieval accuracy is the binding constraint
- Workloads that can be kept under the long-context threshold, where the effective rate stays at $10 / $50
Watch out for
- Long-context billing is a cliff, not a taper: a request over the long-context threshold is rebilled in full at $20 per million input and $75 per million output, so a prompt that crosses it costs roughly double
- GPT-6 Astra is the first publicly released model OpenAI classifies as crossing the Critical cybersecurity threshold under its own Preparedness Framework, which carries additional deployment safeguards
- Vendor-reported benchmark figures come from OpenAI’s own launch material and its own harness; they are not independently reproduced here
Claude Opus 5.5 vs GPT-6 Astra FAQ
Which is cheaper, Claude Opus 5.5 or GPT-6 Astra?
Claude Opus 5.5 is 60% cheaper per 1M input tokens than GPT-6 Astra, $4 vs $10. For 10M input and 2M output tokens, Claude Opus 5.5 costs $80 and GPT-6 Astra $200 at standard rates.
Which is cheaper with prompt caching, Claude Opus 5.5 or GPT-6 Astra?
Claude Opus 5.5 charges $0.20 per 1M cached input tokens, 95% below its standard input rate, and GPT-6 Astra $1, 90% below. With 9M of 10M input tokens cached and 2M output tokens, Claude Opus 5.5 costs $45.80 and GPT-6 Astra $119.
Which scores higher on independent benchmarks, Claude Opus 5.5 or GPT-6 Astra?
Claude Opus 5.5 leads on Arena Text, 1507 Elo to 1475 Elo; GPT-6 Astra leads on GPQA Diamond, 95.8% to 90.6%; GPT-6 Astra leads on FrontierMath Tiers 1-3 (v2), 93.7% to 91.2%. Scores are independent evaluations, not either vendor's launch figures.
Which has the larger context window, Claude Opus 5.5 or GPT-6 Astra?
GPT-6 Astra has the larger context window, 1,050,000 vs 1,000,000 tokens. Both return up to 128,000 tokens per response.
Articles on Claude Opus 5.5 and GPT-6 Astra
- GDPval-AA Chart Fact-Check: Opus 5.5 vs GPT-6 Astra on CostSeptember 24, 2026 · compares both
- Claude Opus 5.5 Benchmarks: What the Chart Shows and HidesSeptember 23, 2026 · compares both
- Gemini 4 Argon Benchmarks: What Independent Tests ShowOctober 1, 2026
- Gemini 4 Pro Leaks: What's Verified and What's HypeOctober 1, 2026
- GPT-6 Sol vs Claude Opus 5.5, Plus Luna: Best Value per TaskSeptember 24, 2026
- Claude Opus 5.5: Tops the Independent Index at a Lower PriceSeptember 23, 2026
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Production evaluation
Choosing between Claude Opus 5.5 and GPT-6 Astra?
Public benchmarks narrow the shortlist. We run both on your own tasks, data and cost limits, then build the routing and review controls to run the winner in production.
- A head-to-head evaluation on your real workload
- Routing between models by cost and difficulty