GPT-6 Astra (Fast) vs Kimi K2.8 Preview
GPT-6 Astra (Fast) comes out ahead, 72 to 66 on our weighted score, and it is the cheaper option too.
- Our pick
OpenAIGPT-6 Astra (Fast)
72/100- ECI—
- Price$20.00 / $100.00
- Context1.05M
Moonshot AIKimi K2.8 Preview
66/100- ECI—
- Price—
- Context1.05M
Add a model
Make it a three-way comparison.
GPT-6 Astra (Fast) is our pick
GPT-6 Astra (Fast) is the better all-round choice, scoring 72/100 against Kimi K2.8 Preview (66). 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 priceGPT-6 Astra (Fast)GPT-6 Astra (Fast) $40.00 per 1M tokens (3:1 blend) · Kimi K2.8 Preview unpriced
- Longest contextAbout the sameGPT-6 Astra (Fast) 1,050,000 · Kimi K2.8 Preview 1,048,576 tokens
- Widest inputsSame inputsGPT-6 Astra (Fast): Text, Images, PDFs · Kimi K2.8 Preview: Text, Images, Video
- Self-hostingNo open weightsBoth are available only through APIs
| Measure | Weight | GPT-6 Astra (Fast) | Kimi K2.8 Preview |
|---|---|---|---|
| Inputs & features | 60% | 80 | 70 |
| Context window | 40% | 61 | 61 |
| Overall | 100% | 72/100 | 66/100 |
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-6 Astra (Fast)OpenAI | Kimi K2.8 PreviewMoonshot AI |
|---|---|---|
| Capability | ||
| Capabilities Index (ECI) | — | — |
| ECI rank | — | — |
| Price per million tokens | ||
| Input | $20.00 | — |
| Output | $100.00 | — |
| Cached input | — | — |
| Blended (3:1) | $40.00 | — |
| Long-context rate | Same rate | — |
| Price source | Median of 1 providers | — |
| Limits | ||
| Context window | 1,050,000 tokens (best) | 1,048,576 tokens |
| Max output | 128,000 tokens | — |
| Inputs and features | ||
| Text | Yes | Yes |
| Images | Yes | Yes |
| PDFs | Yes | No |
| Audio | No | No |
| Video | No | Yes |
| Reasoning | Yes | Yes |
| Tool calling | Yes | Yes |
| Structured output | Yes | No |
| Availability | ||
| Weights | Proprietary | Proprietary |
| API model ID | — | — |
| API providers | 1 | — |
| Released | Sep 4, 2026 | Sep 11, 2026 |
| Knowledge cutoff | — | — |
What would a month cost?
Enter your expected volume in millions of tokens. List prices only; caching and batch discounts would lower these.
- GPT-6 Astra (Fast)$400.00
- Kimi K2.8 Preview—
Which should you choose?
Which is better: GPT-6 Astra (Fast) or Kimi K2.8 Preview?
GPT-6 Astra (Fast) is the better all-round choice, scoring 72/100 against Kimi K2.8 Preview (66). 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-6 Astra (Fast) or Kimi K2.8 Preview?
GPT-6 Astra (Fast) is cheaper at $20.00 input / $100.00 output per million tokens (median across 1 API provider). . At a typical mix of three input tokens to one output token, that is $40.00 per million tokens for GPT-6 Astra (Fast) versus . Kimi K2.8 Preview has no published per-token price.
Which scores higher on benchmarks?
There is no independent benchmark that covers both models yet. GPT-6 Astra (Fast) has not been scored yet and Kimi K2.8 Preview has not been scored yet.
Which is better for coding?
There are no published SWE-bench Verified results for GPT-6 Astra (Fast) and Kimi K2.8 Preview 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?
Their context windows are effectively the same size: GPT-6 Astra (Fast) 1,050,000 and Kimi K2.8 Preview 1,048,576 tokens. Maximum output per response: GPT-6 Astra (Fast) up to 128,000 tokens.
Which can read images, PDFs, audio or video?
GPT-6 Astra (Fast) accepts text, images and PDFs; Kimi K2.8 Preview accepts text, images and video. They handle the same number of input types.
Are any of these open source?
No. GPT-6 Astra (Fast) and Kimi K2.8 Preview are proprietary and only available through APIs and apps.
Which is newer?
Kimi K2.8 Preview is the newest, released Sep 11, 2026. GPT-6 Astra (Fast) came out Sep 4, 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.
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