GPT-5.1 vs Inkling vs Claude Opus 4.5
Too close to call on our weighted score (GPT-5.1 60, Inkling 59, Claude Opus 4.5 55). The right pick depends on what you value most.
OpenAIGPT-5.1
60/100- ECI149.7
- Price$1.25 / $10.00
- Context400K
Thinking MachinesInkling
59/100- ECI148.6
- Price$3.74 / $9.36
- Context1.05M
AnthropicClaude Opus 4.5
55/100- ECI150.1
- Price$5.00 / $25.00
- Context200K
Too close to call
It is close. Our weighted score puts them within 1 points (GPT-5.1 60/100, Inkling 59/100, Claude Opus 4.5 55/100), so choose by what matters most for your work: Claude Opus 4.5 for raw capability, GPT-5.1 on price and Inkling for long inputs. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
- CapabilityClaude Opus 4.5Capabilities Index (ECI): Claude Opus 4.5 150.1 · GPT-5.1 149.7 · Inkling 148.6
- Lowest priceGPT-5.1GPT-5.1 $3.44 · Inkling $5.14 · Claude Opus 4.5 $10.00 per 1M tokens (3:1 blend)
- Longest contextInklingInkling 1,048,576 · GPT-5.1 400,000 · Claude Opus 4.5 200,000 tokens
- Widest inputsInkling and Claude Opus 4.5GPT-5.1: Text, Images · Inkling: Text, Images, Audio · Claude Opus 4.5: Text, Images, PDFs
- Self-hostingInklingPublishes downloadable weights (Apache-2.0)
| Measure | Weight | GPT-5.1 | Inkling | Claude Opus 4.5 |
|---|---|---|---|---|
| CapabilityCapabilities Index (ECI) | 50% | 78 | 76 | 78 |
| Price | 25% | 24 | 16 | 2 |
| Inputs & features | 15% | 70 | 70 | 80 |
| Context window | 10% | 44 | 61 | 32 |
| Overall | 100% | 60/100 | 59/100 | 55/100 |
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | GPT-5.1OpenAI | InklingThinking Machines | Claude Opus 4.5Anthropic |
|---|---|---|---|
| Capability | |||
| Capabilities Index (ECI) | 149.7 | 148.6 | 150.1 (best) |
| ECI rank | #52 of 148 | #57 of 148 | #48 of 148 (best) |
| GPQA DiamondGraduate-level science questions | 87.6% | 88.3% (best) | 86.1% |
| FrontierMath Tiers 1–3Research-level mathematics | — | 33.3% | 34.4% (best) |
| OTIS Mock AIME 2024–2025Competition mathematics | 88.6% | 88.9% (best) | 86.1% |
| SWE-bench VerifiedFixing real GitHub issues | 68.0% | — | 76.7% (best) |
| SimpleQA VerifiedShort factual questions | 48.0% (best) | 40.3% | 45.7% |
| Price per million tokens | |||
| Input | $1.25 (best) | $3.74 | $5.00 |
| Output | $10.00 | $9.36 (best) | $25.00 |
| Cached input | $0.125 (best) | $0.748 | $0.50 |
| Blended (3:1) | $3.44 (best) | $5.14 | $10.00 |
| Long-context rate | Same rate | Same rate | Same rate |
| Price source | Official OpenAI API | Official Thinking Machines API | Official Anthropic API |
| Limits | |||
| Context window | 400,000 tokens | 1,048,576 tokens (best) | 200,000 tokens |
| Max output | 128,000 tokens | 1,048,576 tokens (best) | 64,000 tokens |
| Inputs and features | |||
| Text | Yes | Yes | Yes |
| Images | Yes | Yes | Yes |
| PDFs | No | No | Yes |
| Audio | No | Yes | No |
| Video | No | No | No |
| Reasoning | Yeslow · medium · high | Yeslow · medium · high · xhigh · max | Yeslow · medium · high |
| Tool calling | Yes | Yes | Yes |
| Structured output | Yes | No | Yes |
| Availability | |||
| Weights | Proprietary | OpenApache-2.0 | Proprietary |
| API model ID | gpt-5.1 | thinkingmachines/Inkling:peft:262144 | claude-opus-4-5 |
| API providers | 21 | 23 | 28 (best) |
| Released | Nov 13, 2025 | Jul 15, 2026 | Nov 24, 2025 |
| Knowledge cutoff | Sep 30, 2024 | — | May 2025 |
What would a month cost?
Enter your expected volume in millions of tokens. List prices only; caching and batch discounts would lower these.
- GPT-5.1$32.50
- Inkling$56.12
- Claude Opus 4.5$100.00
Which should you choose?
Which is better: GPT-5.1, Inkling or Claude Opus 4.5?
It is close. Our weighted score puts them within 1 points (GPT-5.1 60/100, Inkling 59/100, Claude Opus 4.5 55/100), so choose by what matters most for your work: Claude Opus 4.5 for raw capability, GPT-5.1 on price and Inkling for long inputs. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
Which is cheaper, GPT-5.1, Inkling or Claude Opus 4.5?
GPT-5.1 is cheaper at $1.25 input / $10.00 output per million tokens (official OpenAI API price). Inkling costs $3.74 input / $9.36 output per million tokens (official Thinking Machines API price); Claude Opus 4.5 costs $5.00 input / $25.00 output per million tokens (official Anthropic API price). At a typical mix of three input tokens to one output token, that is $3.44 per million tokens for GPT-5.1 versus $5.14 for Inkling (1.5× as much) and $10.00 for Claude Opus 4.5 (2.9× as much).
Which scores higher on benchmarks?
Claude Opus 4.5 scores higher on the Capabilities Index (ECI): Claude Opus 4.5 150.1 (#48 of 148), GPT-5.1 149.7 (#52 of 148) and Inkling 148.6 (#57 of 148). The confidence ranges of the top two overlap (147.9–153.0 vs 148.3–151.1), so treat the gap as small. On individual benchmarks: GPQA Diamond — Inkling 88.3%, GPT-5.1 87.6%, Claude Opus 4.5 86.1%; OTIS Mock AIME 2024–2025 — Inkling 88.9%, GPT-5.1 88.6%, Claude Opus 4.5 86.1%; SimpleQA Verified — GPT-5.1 48.0%, Claude Opus 4.5 45.7%, Inkling 40.3%.
Which is better for coding?
There are no published SWE-bench Verified results for Inkling yet, so there is no like-for-like coding score. On overall capability, Claude Opus 4.5 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?
Inkling has the largest context window at 1,048,576 tokens, against 400,000 for GPT-5.1 and 200,000 for Claude Opus 4.5. Maximum output per response: GPT-5.1 up to 128,000, Inkling up to 1,048,576, Claude Opus 4.5 up to 64,000 tokens.
Which can read images, PDFs, audio or video?
GPT-5.1 accepts text and images; Inkling accepts text, images and audio; Claude Opus 4.5 accepts text, images and PDFs. Inkling handles the widest range of inputs.
Are any of these open source?
Inkling publishes its weights (Apache-2.0) and can be self-hosted; GPT-5.1 and Claude Opus 4.5 is proprietary.
Which is newer?
Inkling is the newest, released Jul 15, 2026. Claude Opus 4.5 came out Nov 24, 2025; GPT-5.1 came out Nov 13, 2025. Knowledge cutoff: GPT-5.1 Sep 30, 2024, Claude Opus 4.5 May 2025.
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.
