Claude Opus 4.1 vs Claude Sonnet 3.5 v2 vs o3-pro
Too close to call on our weighted score (o3-pro 51, Claude Opus 4.1 49, Claude Sonnet 3.5 v2 44). The right pick depends on what you value most.
AnthropicClaude Opus 4.1
49/100- ECI144.1
- Price$15.00 / $75.00
- Context200K
- Anthropic
Claude Sonnet 3.5 v2
44/100- ECI133.5
- Price$3.00 / $15.00
- Context200K
OpenAIo3-pro
51/100- ECI147.4
- Price$20.00 / $80.00
- Context200K
Too close to call
It is close. Our weighted score puts them within 2 points (o3-pro 51/100, Claude Opus 4.1 49/100, Claude Sonnet 3.5 v2 44/100), so choose by what matters most for your work: o3-pro for raw capability and Claude Sonnet 3.5 v2 on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
- Capabilityo3-proCapabilities Index (ECI): o3-pro 147.4 · Claude Opus 4.1 144.1 · Claude Sonnet 3.5 v2 133.5
- Lowest priceClaude Sonnet 3.5 v2Claude Sonnet 3.5 v2 $6.00 · Claude Opus 4.1 $30.00 · o3-pro $35.00 per 1M tokens (3:1 blend)
- Longest contextAbout the sameClaude Opus 4.1 200,000 · Claude Sonnet 3.5 v2 200,000 · o3-pro 200,000 tokens
- Widest inputsClaude Opus 4.1 and Claude Sonnet 3.5 v2Claude Opus 4.1: Text, Images, PDFs · Claude Sonnet 3.5 v2: Text, Images, PDFs · o3-pro: Text, Images
- Self-hostingNo open weightsAll three are available only through APIs
| Measure | Weight | Claude Opus 4.1 | Claude Sonnet 3.5 v2 | o3-pro |
|---|---|---|---|---|
| CapabilityCapabilities Index (ECI) | 50% | 71 | 57 | 75 |
| Price | 25% | 0 | 13 | 0 |
| Inputs & features | 15% | 70 | 60 | 70 |
| Context window | 10% | 32 | 32 | 32 |
| Overall | 100% | 49/100 | 44/100 | 51/100 |
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | Claude Opus 4.1Anthropic | Claude Sonnet 3.5 v2Anthropic | o3-proOpenAI |
|---|---|---|---|
| Capability | |||
| Capabilities Index (ECI) | 144.1 | 133.5 | 147.4 (best) |
| ECI rank | #81 of 148 | #119 of 148 | #60 of 148 (best) |
| GPQA DiamondGraduate-level science questions | 77.3% (best) | 55.3% | — |
| FrontierMath Tiers 1–3Research-level mathematics | 12.6% | — | — |
| OTIS Mock AIME 2024–2025Competition mathematics | 68.9% (best) | 8.5% | — |
| SWE-bench VerifiedFixing real GitHub issues | 73.4% | — | — |
| Price per million tokens | |||
| Input | $15.00 | $3.00 (best) | $20.00 |
| Output | $75.00 | $15.00 (best) | $80.00 |
| Cached input | — | — | — |
| Blended (3:1) | $30.00 | $6.00 (best) | $35.00 |
| Long-context rate | Same rate | Same rate | Same rate |
| Price source | Median of 14 providers | Median of 1 providers | Official OpenAI API |
| Limits | |||
| Context window | 200,000 tokens | 200,000 tokens | 200,000 tokens |
| Max output | 32,000 tokens | 8,192 tokens | 100,000 tokens (best) |
| Inputs and features | |||
| Text | Yes | Yes | Yes |
| Images | Yes | Yes | Yes |
| PDFs | Yes | Yes | No |
| Audio | No | No | No |
| Video | No | No | No |
| Reasoning | Yes | No | Yeslow · medium · high |
| Tool calling | Yes | Yes | Yes |
| Structured output | No | No | Yes |
| Availability | |||
| Weights | Proprietary | Proprietary | Proprietary |
| API model ID | — | — | o3-pro |
| API providers | 14 (best) | 1 | 6 |
| Released | Aug 5, 2025 | Oct 22, 2024 | Jun 10, 2025 |
| Knowledge cutoff | Mar 31, 2025 | Apr 30, 2024 | May 2024 |
What would a month cost?
Enter your expected volume in millions of tokens. List prices only; caching and batch discounts would lower these.
- Claude Opus 4.1$300.00
- Claude Sonnet 3.5 v2$60.00
- o3-pro$360.00
Which should you choose?
Which is better: Claude Opus 4.1, Claude Sonnet 3.5 v2 or o3-pro?
It is close. Our weighted score puts them within 2 points (o3-pro 51/100, Claude Opus 4.1 49/100, Claude Sonnet 3.5 v2 44/100), so choose by what matters most for your work: o3-pro for raw capability and Claude Sonnet 3.5 v2 on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
Which is cheaper, Claude Opus 4.1, Claude Sonnet 3.5 v2 or o3-pro?
Claude Sonnet 3.5 v2 is cheaper at $3.00 input / $15.00 output per million tokens (median across 1 API provider). Claude Opus 4.1 costs $15.00 input / $75.00 output per million tokens (median across 14 API providers); o3-pro costs $20.00 input / $80.00 output per million tokens (official OpenAI API price). At a typical mix of three input tokens to one output token, that is $6.00 per million tokens for Claude Sonnet 3.5 v2 versus $30.00 for Claude Opus 4.1 (5× as much) and $35.00 for o3-pro (5.8× as much).
Which scores higher on benchmarks?
o3-pro scores higher on the Capabilities Index (ECI): o3-pro 147.4 (#60 of 148), Claude Opus 4.1 144.1 (#81 of 148) and Claude Sonnet 3.5 v2 133.5 (#119 of 148). The confidence ranges of the top two overlap (145.8–149.7 vs 141.6–146.0), so treat the gap as small.
Which is better for coding?
There are no published SWE-bench Verified results for Claude Sonnet 3.5 v2 and o3-pro yet, so there is no like-for-like coding score. On overall capability, o3-pro leads, which tends to carry over to coding, but test on your own codebase. All three support tool calling for agent workflows.
Which has the bigger context window?
Claude Opus 4.1, Claude Sonnet 3.5 v2 and o3-pro share the same 200,000-token context window. Maximum output per response: Claude Opus 4.1 up to 32,000, Claude Sonnet 3.5 v2 up to 8,192, o3-pro up to 100,000 tokens.
Which can read images, PDFs, audio or video?
Claude Opus 4.1 accepts text, images and PDFs; Claude Sonnet 3.5 v2 accepts text, images and PDFs; o3-pro accepts text and images. Claude Opus 4.1 handles the widest range of inputs.
Are any of these open source?
No. Claude Opus 4.1, Claude Sonnet 3.5 v2 and o3-pro are proprietary and only available through APIs and apps.
Which is newer?
Claude Opus 4.1 is the newest, released Aug 5, 2025. o3-pro came out Jun 10, 2025; Claude Sonnet 3.5 v2 came out Oct 22, 2024. Knowledge cutoff: Claude Opus 4.1 Mar 31, 2025, Claude Sonnet 3.5 v2 Apr 30, 2024, o3-pro May 2024.
How do you decide the winner?
Each model gets a 0–100 score on capability (50%, independent benchmark results); price (25%, blended price per million tokens (3 input : 1 output), log scale); inputs & features (15%, image, PDF, audio and video input, tool calling, structured output and reasoning); context window (10%, maximum tokens per request, log scale). Dimensions missing for any model are dropped and the remaining weights rescaled, so every model is judged on the same evidence. Specs and prices come from public model listings and the labs’ own API pages; capability scores come from independent benchmark runs. Data updated Oct 4, 2026.
Related comparisons
- Claude Opus 4.1 vs Gemini 2.5 ProGoogle · ECI 145.3
- Claude Opus 4.1 vs Qwen3 MaxAlibaba (Qwen) · ECI 142.4
- Claude Opus 4.1 vs DeepSeek-R1-Distill-Qwen-32BDeepSeek · ECI 137.4
- Claude Sonnet 3.5 v2 vs Gemini 2.0 FlashGoogle · ECI 134.7
- Claude Sonnet 3.5 v2 vs GPT-4.1OpenAI · ECI 136.8
- Claude Sonnet 3.5 v2 vs Mistral Large 2.1Mistral AI · ECI 128.5
