AI model comparison
Claude Sonnet 4.5 vs Claude Opus 4.1
Pricing, context window, benchmarks, and features compared side by side. Or skip the guesswork and send one prompt to both.
Anthropic
Claude Sonnet 4.5
Claude Sonnet 4.5 is Anthropic’s most advanced Sonnet model to date, optimized for real-world agents and coding workflows.
- Input / 1M
- $3
- Output / 1M
- $15
- Context
- 1M
Anthropic
Claude Opus 4.1
Claude Opus 4.1 is an updated version of Anthropic’s flagship model, offering improved performance in coding, reasoning, and agentic tasks.
- Input / 1M
- $15
- Output / 1M
- $75
- Context
- 200K
At a glance
Quick verdict
How the two models stack up on the things people ask about most.
Lower price
Claude Sonnet 4.5
5x cheaper for a typical chat
Higher intelligence score
Claude Opus 4.1
22.8 vs 20.7 on Artificial Analysis
Larger context window
Claude Sonnet 4.5
1M vs 200K tokens
Newer release
Claude Sonnet 4.5
Released September 29, 2025
Benchmarks
Benchmark scores
Independent scores from Artificial Analysis. Higher is better.
Intelligence index
Claude Sonnet 4.520.7Claude Opus 4.122.8Coding index
Claude Sonnet 4.552.1Claude Opus 4.1Not availableAgentic index
Claude Sonnet 4.515.8Claude Opus 4.1Not availablePricing
Claude Sonnet 4.5 vs Claude Opus 4.1 API pricing
Per-token API rates. Cheaper option highlighted.
| Metric | Claude Sonnet 4.5 | Claude Opus 4.1 |
|---|---|---|
| Input tokensPer 1M tokens | $3 | $15 |
| Output tokensPer 1M tokens | $15 | $75 |
| Cached input (read)Per 1M tokens | $0.30 | $1.50 |
| Cache writePer 1M tokens | $3.75 | $18.75 |
| Long-context pricingPer 1M tokens, for very long prompts | $6 in / $22.50 out above 200K | Same rate at any length |
| Web searchPer request | $0.01 | $0.01 |
What it costs in practice
Estimated cost per 1,000 requests at standard rates. Coding and long-document figures also show the cost when the input is already cached.
Chat message
2K in, 500 out
Claude Sonnet 4.5$13.50Claude Opus 4.1$67.50Coding task
30K in, 4K out
Claude Sonnet 4.5$150$69 cachedClaude Opus 4.1$750$345 cachedLong document summary
150K in, 2K out
Claude Sonnet 4.5$480$75 cachedClaude Opus 4.1$2400$375 cachedSpecs
Context window and capabilities
How much each model can read, how much it can write, and what it accepts as input.
| Metric | Claude Sonnet 4.5 | Claude Opus 4.1 |
|---|---|---|
| Context window | 1M tokens | 200K tokens |
| Max output | 64K tokens | 32K tokens |
| Input types | File, Image, Text | File, Image, Text |
| Output types | Text | Text |
| Reasoning effort levels | Not available | Not available |
| Default reasoning effort | Not available | Not available |
| Release date | September 29, 2025 | August 5, 2025 |
Features
Supported features
API features available for each model.
| Metric | Claude Sonnet 4.5 | Claude Opus 4.1 |
|---|---|---|
| Tool calling | Supported | Supported |
| Structured outputs | Supported | Not supported |
| JSON mode | Supported | Not supported |
| Reasoning | Supported | Supported |
| Temperature | Supported | Supported |
| Stop sequences | Supported | Supported |
| Deterministic seed | Not supported | Not supported |
| Verbosity control | Not supported | Not supported |
Keep exploring
More on these models
Other head-to-heads, the full model page, and the alternatives list for each model.
Claude Sonnet 4.5View full model details- Claude Sonnet 4.5 vs Claude Sonnet 4.6
- Claude Sonnet 4.5 vs Claude Haiku 4.5
- Claude Sonnet 4.5 vs Claude Opus 4.5
- Claude Sonnet 4.5 vs GPT-5.1
- Claude Sonnet 4.5 vs GPT-5.1-Codex
- Claude Sonnet 4.5 vs Gemini 2.5 Pro
- Claude Sonnet 4.5 vs GPT-5
- Claude Sonnet 4.5 vs o3 Pro
- Claude Sonnet 4.5 vs Qwen3.5 397B A17B
- Claude Sonnet 4.5 vs o3
- Claude Sonnet 4.5 vs Claude Sonnet 4
- Claude Sonnet 4.5 vs o1
Our take
Claude Sonnet 4.5 is 5x cheaper for a typical chat. Claude Opus 4.1 scores higher on the Artificial Analysis Intelligence Index (22.8 vs 20.7). Claude Sonnet 4.5 has the larger context window (1M vs 200K tokens). The right pick depends on your workload, so the quickest way to settle it is to send the same prompt to both and compare.
FAQ
Frequently asked questions
Is Claude Sonnet 4.5 or Claude Opus 4.1 cheaper?
Claude Sonnet 4.5 is cheaper for a typical chat (2K input tokens and 500 output tokens). Claude Sonnet 4.5 costs $3 per 1M input tokens and $15 per 1M output tokens, while Claude Opus 4.1 costs $15 per 1M input tokens and $75 per 1M output tokens.
Which has a bigger context window, Claude Sonnet 4.5 or Claude Opus 4.1?
Claude Sonnet 4.5 supports up to 1M tokens of context, compared with 200K for Claude Opus 4.1.
Is Claude Sonnet 4.5 smarter than Claude Opus 4.1?
On the Artificial Analysis Intelligence Index, Claude Sonnet 4.5 scores 20.7 and Claude Opus 4.1 scores 22.8, putting Claude Opus 4.1 ahead. Benchmarks don't capture everything, so the best test is running your own prompts through both.
Can I use Claude Sonnet 4.5 and Claude Opus 4.1 at the same time?
Yes. Shortcut Chat sends one prompt to multiple models at once, so you can see Claude Sonnet 4.5 and Claude Opus 4.1 answer side by side and keep the better response.
Why choose? Ask both.
Send one prompt to Claude Sonnet 4.5 and Claude Opus 4.1 at the same time. Compare the answers side by side and keep the best one.