MODEL COMPARISON
Claude Opus 5.5 vs Claude Sonnet 5.5
Claude Opus 5.5 scores higher on the Artificial Analysis Intelligence Index (57.6 vs 56.0 for Claude Sonnet 5.5); Claude Sonnet 5.5 costs less per task ($5.46 vs $5.98 for Claude Opus 5.5). Both run through one SandBase API key.
- IntelligenceClaude Opus 5.53% higher
- Cost per taskClaude Sonnet 5.59% cheaper
- Output speedClaude Sonnet 5.539% 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 56.0.
- High request volumeClaude Sonnet 5.5
Claude Sonnet 5.5 finishes the same index for $5.46 instead of $5.98, so the gap compounds with every run.
- Streaming to usersClaude Sonnet 5.5
Claude Sonnet 5.5 returns about 133 tokens per second against 95.
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 | Claude Sonnet 5.5 |
|---|---|---|
| Input / 1M tokens | $3.80 | $1.90Better |
| Output / 1M tokens | $19 | $9.50Better |
| Context window | 1M | 1M |
| Intelligence IndexAA | 57.6Better | 56.0 |
| Cost per taskAA | $5.98 | $5.46Better |
| Output speedAA | 95 tok/s | 133 tok/sBetter |
Rows marked AA — Data: Artificial Analysis, snapshot 2026-10-14. Claude Opus 5.5 on AA ↗ Claude Sonnet 5.5 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 Claude Sonnet 5.5, change "model" to anthropic/claude-sonnet-5.5. 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.
Anthropic
Claude Sonnet 5.5
anthropic/claude-sonnet-5.5Claude Sonnet 5.5 is Anthropic's Sonnet-class model for well-scoped everyday work, succeeding Claude Sonnet 5 as a direct upgrade. It is especially strong at building features and fixing bugs, with a 1M-token context window and text, image, and file input.
FAQ
Which is cheaper, Claude Opus 5.5 or Claude Sonnet 5.5?
On SandBase Claude Opus 5.5 is $3.80 per 1M input tokens and $19 per 1M output tokens; Claude Sonnet 5.5 is $1.90 and $9.50. Claude Sonnet 5.5 has the lower output price.
Is Claude Opus 5.5 better than Claude Sonnet 5.5?
On the Artificial Analysis Intelligence Index Claude Opus 5.5 scores 57.6 and Claude Sonnet 5.5 scores 56.0, 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 $5.46 for Claude Sonnet 5.5, 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 Claude Sonnet 5.5 accepts 1M tokens per request.
Can I use both Claude Opus 5.5 and Claude Sonnet 5.5 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 Anthropic developer accounts.
How do I switch between Claude Opus 5.5 and Claude Sonnet 5.5?
Change the model field in your request from "anthropic/claude-opus-5.5" to "anthropic/claude-sonnet-5.5". 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.