Claude Mythos 5.1 vs GPT-5.6 Cyber
Claude Mythos 5.1 comes out ahead, 66 to 60 on our weighted score.
- Our pick
AnthropicClaude Mythos 5.1
66/100- ECI—
- Price—
- Context1M
OpenAIGPT-5.6 Cyber
60/100- ECI—
- Price$12.50 / $75.00
- Context400K
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Make it a three-way comparison.
Claude Mythos 5.1 is our pick
Claude Mythos 5.1 is the better all-round choice, scoring 66/100 against GPT-5.6 Cyber (60). It leads on context window. The score weighs inputs & features 60%, context window 40%. None of the shared benchmarks cover every model here yet, so capability is left out of this verdict.
- CapabilityNot enough dataNo independent benchmark covers every model here yet
- Lowest priceGPT-5.6 CyberGPT-5.6 Cyber $28.13 per 1M tokens (3:1 blend) · Claude Mythos 5.1 unpriced
- Longest contextClaude Mythos 5.1Claude Mythos 5.1 1,000,000 · GPT-5.6 Cyber 400,000 tokens
- Widest inputsClaude Mythos 5.1Claude Mythos 5.1: Text, Images, PDFs · GPT-5.6 Cyber: Text, Images
- Self-hostingNo open weightsBoth are available only through APIs
| Measure | Weight | Claude Mythos 5.1 | GPT-5.6 Cyber |
|---|---|---|---|
| Inputs & features | 60% | 70 | 70 |
| Context window | 40% | 60 | 44 |
| Overall | 100% | 66/100 | 60/100 |
Left out because at least one model lacks the data: capability and price. The remaining weights were rescaled.
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | Claude Mythos 5.1Anthropic | GPT-5.6 CyberOpenAI |
|---|---|---|
| Capability | ||
| Capabilities Index (ECI) | — | — |
| ECI rank | — | — |
| Price per million tokens | ||
| Input | — | $12.50 |
| Output | — | $75.00 |
| Cached input | — | $1.25 |
| Blended (3:1) | — | $28.13 |
| Long-context rate | — | Same rate |
| Price source | — | Official OpenAI API |
| Limits | ||
| Context window | 1,000,000 tokens (best) | 400,000 tokens |
| Max output | 128,000 tokens | 128,000 tokens |
| Inputs and features | ||
| Text | Yes | Yes |
| Images | Yes | Yes |
| PDFs | Yes | No |
| Audio | No | No |
| Video | No | No |
| Reasoning | Yes | Yeslow · medium · high · xhigh · max |
| Tool calling | Yes | Yes |
| Structured output | No | Yes |
| Availability | ||
| Weights | Proprietary | Proprietary |
| API model ID | — | gpt-daybreak-red-latest |
| API providers | — | 1 |
| Released | Sep 1, 2026 | Aug 7, 2026 |
| Knowledge cutoff | Jun 2026 | Feb 16, 2026 |
What would a month cost?
Enter your expected volume in millions of tokens. List prices only; caching and batch discounts would lower these.
- Claude Mythos 5.1—
- GPT-5.6 Cyber$275.00
Which should you choose?
Which is better: Claude Mythos 5.1 or GPT-5.6 Cyber?
Claude Mythos 5.1 is the better all-round choice, scoring 66/100 against GPT-5.6 Cyber (60). It leads on context window. The score weighs inputs & features 60%, context window 40%. None of the shared benchmarks cover every model here yet, so capability is left out of this verdict.
Which is cheaper, Claude Mythos 5.1 or GPT-5.6 Cyber?
GPT-5.6 Cyber is cheaper at $12.50 input / $75.00 output per million tokens (official OpenAI API price). . At a typical mix of three input tokens to one output token, that is $28.13 per million tokens for GPT-5.6 Cyber versus . Claude Mythos 5.1 has no published per-token price.
Which scores higher on benchmarks?
There is no independent benchmark that covers both models yet. Claude Mythos 5.1 has not been scored yet and GPT-5.6 Cyber has not been scored yet.
Which is better for coding?
There are no published SWE-bench Verified results for Claude Mythos 5.1 and GPT-5.6 Cyber yet, so there is no like-for-like coding score. Test both on a sample of your own tasks. Both support tool calling for agent workflows.
Which has the bigger context window?
Claude Mythos 5.1 has the largest context window at 1,000,000 tokens, against 400,000 for GPT-5.6 Cyber. Maximum output per response: Claude Mythos 5.1 up to 128,000, GPT-5.6 Cyber up to 128,000 tokens.
Which can read images, PDFs, audio or video?
Claude Mythos 5.1 accepts text, images and PDFs; GPT-5.6 Cyber accepts text and images. Claude Mythos 5.1 handles the widest range of inputs.
Are any of these open source?
No. Claude Mythos 5.1 and GPT-5.6 Cyber are proprietary and only available through APIs and apps.
Which is newer?
Claude Mythos 5.1 is the newest, released Sep 1, 2026. GPT-5.6 Cyber came out Aug 7, 2026. Knowledge cutoff: Claude Mythos 5.1 Jun 2026, GPT-5.6 Cyber Feb 16, 2026.
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 Nov 2, 2026.
