Claude Opus 5.5 vs GPT-6 Astra
Claude Opus 5.5 costs $4.00 / $20.00 and GPT-6 Astra costs $10.00 / $50.00 per million input / output tokens. At a typical 3:1 mix, Claude Opus 5.5 is 2.5× cheaper than GPT-6 Astra.
Input
$4.00
per 1M
Output
$20.00
per 1M
Cached
$0.20
1M context
GPT-6 Astra
OpenAI
Input
$10.00
per 1M
Output
$50.00
per 1M
Cached
$1.00
1.05M context
Side by side
Green marks the cheaper price, larger context window, bigger discount or higher score.
| Detail | Claude Opus 5.5 | GPT-6 Astra |
|---|---|---|
| Input per 1M | $4.00 | $10.00 |
| Output per 1M | $20.00 | $50.00 |
| Blended per 1M (3:1) | $8.00 | $20.00 |
| Cached input per 1M | $0.20 | $1.00 |
| Batch or off-peak discount | 50% (batch) | 50% (batch) |
| Long prompts | Same rate at any length | Over 272K: 2× in, 1.5× out |
| Context window | 1M | 1.05M |
| Released | 22 Sep 2026 | 3 Sep 2026 |
| Open weights | No | No |
| Arena text score | 1509 | 1478 |
| Verified | 27 Sep 2026 | 27 Sep 2026 |
Sources: Anthropic pricing and OpenAI pricing.
Monthly cost on three workloads
List prices, no batch discount. The cached share applies where a model has a cache rate.
| Workload | Claude Opus 5.5 | GPT-6 Astra | Difference |
|---|---|---|---|
| Customer chat assistant50,000 conversations a month, about 2,000 tokens in and 400 out each; 50% cached | $610 | $1,550 | $940 |
| Document Q&A (RAG)20,000 questions a month over retrieved documents, 12,000 in and 600 out; 30% cached | $926 | $2,352 | $1,426 |
| Coding agent400 tasks a month, 40 steps each with a growing context; 85% cached | $738 | $2,163 | $1,425 |
How they differ
- Claude Opus 5.5 is cheaper on input ($4 vs $10).
- Claude Opus 5.5 is cheaper on output ($20 vs $50), which matters most for long answers and reasoning models.
- GPT-6 Astra accepts longer prompts (1.05M vs 1M tokens).
- Cached input is cheaper on Claude Opus 5.5 ($0.20 vs $1), which favours agents and chat apps that resend the same context.
- On the Arena text leaderboard (25 Sep 2026), Claude Opus 5.5 scores higher (1509 vs 1478). Test both on your own prompts before deciding.
Recent changes
All changes- ▼ 20%Claude Opus 5.5 launched at $4 / $20 per 1M tokens, 20% below Opus 5.
- OpenAI launched GPT-6 Sol at $2 / $10 and GPT-6 Luna at $0.10 / $0.50.
- OpenAI launched GPT-6 Astra at $10 / $50, its most expensive standard model.
- Anthropic retired Claude Opus 4.1.
- Anthropic launched Claude Opus 5 at $5 / $25.
Related comparisons
Compare any two- Claude Opus 5.5 vs GPT-6 Sol$4.00 / $20.00 · $2.00 / $10.00
- Claude Fable 5.1 vs GPT-6 Astra$10.00 / $50.00 · $10.00 / $50.00
Kimi K3 vs Claude Opus 5.5$3.00 / $15.00 · $4.00 / $20.00
Gemini 3.1 Pro vs GPT-6 Astra$2.00 / $12.00 · $10.00 / $50.00- Claude Opus 5.5 vs Gemini 3.1 Pro$4.00 / $20.00 · $2.00 / $12.00
Grok 4.7 vs Claude Opus 5.5$2.00 / $6.00 · $4.00 / $20.00