Claude Opus 5.5 vs Claude Sonnet 5: pricing and benchmarks
Claude Sonnet 5 is 50% cheaper on input tokens ($2.00 vs $4.00 per 1M). Claude Sonnet 5 is 50% cheaper on output tokens ($10.00 vs $20.00 per 1M). On our document Q&A workload (50,000 questions a month), Claude Sonnet 5 costs $1,100 a month versus $2,200 for Claude Opus 5.5, 50% less. Epoch AI has not published a capability index score for Claude Opus 5.5 yet.
Prices verified September 26, 2026.
Which should you choose?
Epoch AI has not published a capability index score for Claude Opus 5.5 yet.
Claude Sonnet 5 costs $4.00 per 1M tokens (3:1 input-to-output mix) vs $8.00 for Claude Opus 5.5, 50% less.
Pricing and specs
| Claude Opus 5.5 | Claude Sonnet 5 | |
|---|---|---|
| Provider | Anthropic | Anthropic |
| API model ID | claude-opus-5-5 | claude-sonnet-5 |
| Input / 1M tokens | $4.00 | $2.00 |
| Cached input / 1M tokens | $0.20 | $0.20 |
| Output / 1M tokens | $20.00 | $10.00 |
| Long-context rates | — | — |
| Context window | 1M tokens | 1M tokens |
| Max output | 128K tokens | 128K tokens |
| Batch discount | 50% off | 50% off |
Benchmarks
| Claude Opus 5.5 | Claude Sonnet 5 | |
|---|---|---|
| Epoch Capabilities Index | — | 156.2 |
| GPQA Diamond· Science reasoning | — | 87.4% |
| FrontierMath (Tiers 1–3)· Advanced math | — | 65.6% |
| SimpleQA Verified· Factual accuracy | — | 33.7% |
| ARC-AGI-2· Abstract reasoning | — | — |
| DeepSWE· Coding | — | 53.8% |
| APEX-Agents· Agentic work | — | 32.5% |
Source: Epoch AI, best recorded result per model (CC BY 4.0). A dash means no published score. See all benchmarks
Monthly cost for real workloads
| Workload | Claude Opus 5.5 | Claude Sonnet 5 | Difference |
|---|---|---|---|
Support chatbot 100,000 replies a month, ~1,500 input tokens (system prompt + history) and ~400 output tokens each. | $1,400 | $700.00 | Claude Sonnet 5 50% cheaper |
Document Q&A (RAG) 50,000 questions a month with ~8,000 tokens of retrieved context and ~600 output tokens each. | $2,200 | $1,100 | Claude Sonnet 5 50% cheaper |
Coding agent 10,000 agent steps a month, ~40,000 input tokens each (70% read from the prompt cache) and ~2,000 output tokens. | $936.00 | $496.00 | Claude Sonnet 5 47% cheaper |
Estimates use standard list prices and ignore cache-write surcharges. Different tokenizers can count the same text differently, so test with your own prompts.
Claude Opus 5.5 vs Claude Sonnet 5 cost calculator
- $1,100/mo$0.02 / request
- Claude Opus 5.5Anthropic$2,200/mo$0.04 / request
Standard-tier list prices. Long-context rates apply automatically where the provider publishes a threshold. Excludes cache-write surcharges, taxes, batch and volume discounts.
Claude Opus 5.5 pricing notes
Anthropic’s recommended default model for most workloads, with adaptive thinking always on.
- Cache reads cost 5% of the input price, against 10% on Claude Opus 5 and Sonnet 5.
- Cache writes cost $5 (5-minute cache) or $8 (1-hour cache) per 1M tokens.
- US-only inference (inference_geo: "us") costs 1.1x.
Claude Sonnet 5 pricing notes
Anthropic’s best combination of speed and intelligence.
- The $2 / $10 launch price is now the standard price; the planned rise to $3 / $15 will not happen.
- Cache writes cost $2.50 (5-minute cache) or $4 (1-hour cache) per 1M tokens.
- Uses Anthropic’s newer tokenizer, which produces roughly 30% more tokens for the same text.
Frequently asked questions
- Is Claude Opus 5.5 cheaper than Claude Sonnet 5?
- Claude Sonnet 5 is 50% cheaper on input tokens ($2.00 vs $4.00 per 1M). Claude Sonnet 5 is 50% cheaper on output tokens ($10.00 vs $20.00 per 1M). On our document Q&A workload (50,000 questions a month), Claude Sonnet 5 costs $1,100 a month versus $2,200 for Claude Opus 5.5, 50% less.
- Which is more capable, Claude Opus 5.5 or Claude Sonnet 5?
- Epoch AI has not published a capability index score for Claude Opus 5.5 yet.
- How much does Claude Opus 5.5 cost per 1M tokens?
- Claude Opus 5.5 costs $4.00 per 1M input tokens and $20.00 per 1M output tokens, and $0.20 per 1M cached input tokens on Anthropic’s standard tier.
- How much does Claude Sonnet 5 cost per 1M tokens?
- Claude Sonnet 5 costs $2.00 per 1M input tokens and $10.00 per 1M output tokens, and $0.20 per 1M cached input tokens on Anthropic’s standard tier.
- Which has the larger context window, Claude Opus 5.5 or Claude Sonnet 5?
- Both offer a 1M-token context window.