GPT-5.6 Cyber vs Kimi K2.8 Preview vs Claude Mythos 5
Claude Mythos 5 comes out ahead, 72 to 66 and 60 on our weighted score, and it is the cheaper option too.
OpenAIGPT-5.6 Cyber
60/100- ECI—
- Price$12.50 / $75.00
- Context400K
Moonshot AIKimi K2.8 Preview
66/100- ECI—
- Price—
- Context1.05M
- Our pick
AnthropicClaude Mythos 5
72/100- ECI—
- Price$10.00 / $50.00
- Context1M
Claude Mythos 5 is our pick
Claude Mythos 5 is the better all-round choice, scoring 72/100 against Kimi K2.8 Preview (66) and GPT-5.6 Cyber (60). It leads on inputs & features. 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 priceClaude Mythos 5Claude Mythos 5 $20.00 · GPT-5.6 Cyber $28.13 per 1M tokens (3:1 blend) · Kimi K2.8 Preview unpriced
- Longest contextKimi K2.8 PreviewKimi K2.8 Preview 1,048,576 · Claude Mythos 5 1,000,000 · GPT-5.6 Cyber 400,000 tokens
- Widest inputsKimi K2.8 Preview and Claude Mythos 5GPT-5.6 Cyber: Text, Images · Kimi K2.8 Preview: Text, Images, Video · Claude Mythos 5: Text, Images, PDFs
- Self-hostingNo open weightsAll three are available only through APIs
| Measure | Weight | GPT-5.6 Cyber | Kimi K2.8 Preview | Claude Mythos 5 |
|---|---|---|---|---|
| Inputs & features | 60% | 70 | 70 | 80 |
| Context window | 40% | 44 | 61 | 60 |
| Overall | 100% | 60/100 | 66/100 | 72/100 |
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 | GPT-5.6 CyberOpenAI | Kimi K2.8 PreviewMoonshot AI | Claude Mythos 5Anthropic |
|---|---|---|---|
| Capability | |||
| Capabilities Index (ECI) | — | — | — |
| ECI rank | — | — | — |
| Price per million tokens | |||
| Input | $12.50 | — | $10.00 (best) |
| Output | $75.00 | — | $50.00 (best) |
| Cached input | $1.25 | — | — |
| Blended (3:1) | $28.13 | — | $20.00 (best) |
| Long-context rate | Same rate | — | Same rate |
| Price source | Official OpenAI API | — | Median of 2 providers |
| Limits | |||
| Context window | 400,000 tokens | 1,048,576 tokens (best) | 1,000,000 tokens |
| Max output | 128,000 tokens | — | 128,000 tokens |
| Inputs and features | |||
| Text | Yes | Yes | Yes |
| Images | Yes | Yes | Yes |
| PDFs | No | No | Yes |
| Audio | No | No | No |
| Video | No | Yes | No |
| Reasoning | Yeslow · medium · high · xhigh · max | Yes | Yes |
| Tool calling | Yes | Yes | Yes |
| Structured output | Yes | No | Yes |
| Availability | |||
| Weights | Proprietary | Proprietary | Proprietary |
| API model ID | gpt-daybreak-red-latest | — | — |
| API providers | 1 | — | 2 (best) |
| Released | Aug 7, 2026 | Sep 11, 2026 | Jun 9, 2026 |
| Knowledge cutoff | Feb 16, 2026 | — | Jan 31, 2026 |
What would a month cost?
Enter your expected volume in millions of tokens. List prices only; caching and batch discounts would lower these.
- GPT-5.6 Cyber$275.00
- Kimi K2.8 Preview—
- Claude Mythos 5$200.00
Which should you choose?
Which is better: GPT-5.6 Cyber, Kimi K2.8 Preview or Claude Mythos 5?
Claude Mythos 5 is the better all-round choice, scoring 72/100 against Kimi K2.8 Preview (66) and GPT-5.6 Cyber (60). It leads on inputs & features. 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, GPT-5.6 Cyber, Kimi K2.8 Preview or Claude Mythos 5?
Claude Mythos 5 is cheaper at $10.00 input / $50.00 output per million tokens (median across 2 API providers). GPT-5.6 Cyber costs $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 $20.00 per million tokens for Claude Mythos 5 versus $28.13 for GPT-5.6 Cyber (1.4× as much). Kimi K2.8 Preview has no published per-token price.
Which scores higher on benchmarks?
There is no independent benchmark that covers all three models yet. GPT-5.6 Cyber has not been scored yet, Kimi K2.8 Preview has not been scored yet and Claude Mythos 5 has not been scored yet.
Which is better for coding?
There are no published SWE-bench Verified results for GPT-5.6 Cyber, Kimi K2.8 Preview and Claude Mythos 5 yet, so there is no like-for-like coding score. Test both on a sample of your own tasks. All three support tool calling for agent workflows.
Which has the bigger context window?
Kimi K2.8 Preview has the largest context window at 1,048,576 tokens, against 1,000,000 for Claude Mythos 5 and 400,000 for GPT-5.6 Cyber. Maximum output per response: GPT-5.6 Cyber up to 128,000, Claude Mythos 5 up to 128,000 tokens.
Which can read images, PDFs, audio or video?
GPT-5.6 Cyber accepts text and images; Kimi K2.8 Preview accepts text, images and video; Claude Mythos 5 accepts text, images and PDFs. Kimi K2.8 Preview handles the widest range of inputs.
Are any of these open source?
No. GPT-5.6 Cyber, Kimi K2.8 Preview and Claude Mythos 5 are proprietary and only available through APIs and apps.
Which is newer?
Kimi K2.8 Preview is the newest, released Sep 11, 2026. GPT-5.6 Cyber came out Aug 7, 2026; Claude Mythos 5 came out Jun 9, 2026. Knowledge cutoff: GPT-5.6 Cyber Feb 16, 2026, Claude Mythos 5 Jan 31, 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 Oct 4, 2026.
