MODEL COMPARISON
Claude Opus 5.5 vs GPT-6 Astra
Claude Opus 5.5 scores higher on the Artificial Analysis Intelligence Index (57.6 vs 52.7 for GPT-6 Astra); GPT-6 Astra costs less per task ($3.26 vs $5.98 for Claude Opus 5.5). Both run through one SandBase API key.
- IntelligenceClaude Opus 5.59% higher
- Cost per taskGPT-6 Astra46% cheaper
- Output speedClaude Opus 5.577% faster
Which one to pick
Each line is backed by a number in the table below.
- The hardest reasoningClaude Opus 5.5
Claude Opus 5.5 leads the Intelligence Index, 57.6 against 52.7.
- High request volumeGPT-6 Astra
GPT-6 Astra finishes the same index for $3.26 instead of $5.98, so the gap compounds with every run.
- Streaming to usersClaude Opus 5.5
Claude Opus 5.5 returns about 95 tokens per second against 54.
Side by side
Prices are per 1M tokens on SandBase, after any public discount. Better value per row is marked.
| Metric | Claude Opus 5.5 | GPT-6 Astra |
|---|---|---|
| Input / 1M tokens | $3.80Better | $9 |
| Output / 1M tokens | $19Better | $45 |
| Context window | 1M | 1.1MBetter |
| Intelligence IndexAA | 57.6Better | 52.7 |
| Coding IndexAA | — | 76.9 |
| Agentic IndexAA | — | 51.0 |
| Cost per taskAA | $5.98 | $3.26Better |
| Output speedAA | 95 tok/sBetter | 54 tok/s |
Rows marked AA — Data: Artificial Analysis, snapshot 2026-10-14. Claude Opus 5.5 on AA ↗ GPT-6 Astra on AA ↗ Full rankings: SandBase Lab leaderboards.
Switching between them
Same key, same endpoint, same request shape.
curl https://api.sandbase.ai/v1/chat/completions \
-H "Authorization: Bearer $SANDBASE_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"model": "anthropic/claude-opus-5.5",
"messages": [{"role": "user", "content": "Hello"}]
}'To run the same prompt on GPT-6 Astra, change "model" to openai/gpt-6-astra. Nothing else changes, so you can A/B both on your own prompts before committing.
Both models
Pricing, playground and reference for each.
Anthropic
Claude Opus 5.5
anthropic/claude-opus-5.5Claude Opus 5.5 is the most powerful model in the Claude 5 family from Anthropic. It excels at complex reasoning, analysis, and creative tasks with superior accuracy and nuance. It supports text, image, and file inputs with text output, reasoning support and a 1M-token context window.
OpenAI
GPT-6 Astra
openai/gpt-6-astraGPT-6 Astra is OpenAI's flagship GPT-6 reasoning model, described by OpenAI as its most capable model for the most demanding work, with text and image input. OpenAI recommends it for complex reasoning, coding, computer use, research and document creation, including multi-step workflows across code, browsers and professional software. It is the top tier above GPT-6.1 Sol and GPT-6 Luna; choose it when quality matters most, or the Astra Pro variant for the hardest requests.
FAQ
Which is cheaper, Claude Opus 5.5 or GPT-6 Astra?
On SandBase Claude Opus 5.5 is $3.80 per 1M input tokens and $19 per 1M output tokens; GPT-6 Astra is $9 and $45. Claude Opus 5.5 has the lower output price.
Is Claude Opus 5.5 better than GPT-6 Astra?
On the Artificial Analysis Intelligence Index Claude Opus 5.5 scores 57.6 and GPT-6 Astra scores 52.7, so Claude Opus 5.5 is ahead on general capability. Cost and speed can point the other way, so check the table above for the metric that matters to your workload.
What does each model cost per task?
Artificial Analysis measures $5.98 per task for Claude Opus 5.5 and $3.26 for GPT-6 Astra, running the same Intelligence Index workload. That figure folds in how many tokens each model spends on reasoning, so it tracks real spend better than the per-token price alone.
How big is the context window of each model?
Claude Opus 5.5 accepts 1M tokens and GPT-6 Astra accepts 1.1M tokens per request.
Can I use both Claude Opus 5.5 and GPT-6 Astra with one API key?
Yes. Both run through SandBase, so a single API key and balance covers them and the rest of the catalog. You do not need separate Anthropic and OpenAI developer accounts.
How do I switch between Claude Opus 5.5 and GPT-6 Astra?
Change the model field in your request from "anthropic/claude-opus-5.5" to "openai/gpt-6-astra". The endpoint, key and request shape stay the same, which makes it cheap to A/B the two on your own prompts.
Where do these benchmark numbers come from?
The Intelligence, Coding and Agentic indexes, cost per task and output speed come from Artificial Analysis, from the snapshot dated 2026-10-14. Prices are SandBase list prices after any public discount. Numbers move as new snapshots land.
Keep comparing
See all comparisons, browse the language model catalog, or check the full Artificial Analysis leaderboards in SandBase Lab.