Kimi K2.8 Preview vs Sakana Namazu vs Step 5 Preview
Step 5 Preview comes out ahead, 56 to 51 and 50 on our weighted score, and it is the cheaper option too.
Moonshot AIKimi K2.8 Preview
51/100- ECI—
- Price$1.00 / $4.00
- Context1.05M
Sakana AISakana Namazu
50/100- ECI—
- Price$0.95 / $4.00
- Context262K
- Our pick
StepFunStep 5 Preview
56/100- ECI—
- Price$1.00 / $2.70
- Context1M
Step 5 Preview is our pick
Step 5 Preview is the better all-round choice, scoring 56/100 against Kimi K2.8 Preview (51) and Sakana Namazu (50). It leads on price. The score weighs price 50%, inputs & features 30%, context window 20%. 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 priceStep 5 PreviewStep 5 Preview $1.43 · Sakana Namazu $1.71 · Kimi K2.8 Preview $1.75 per 1M tokens (3:1 blend)
- Longest contextKimi K2.8 PreviewKimi K2.8 Preview 1,048,576 · Step 5 Preview 1,000,000 · Sakana Namazu 262,144 tokens
- Widest inputsSame inputsKimi K2.8 Preview: Text, Images, Video · Sakana Namazu: Text, Images, PDFs · Step 5 Preview: Text, Images, Video
- Self-hostingStep 5 PreviewPublishes downloadable weights
| Measure | Weight | Kimi K2.8 Preview | Sakana Namazu | Step 5 Preview |
|---|---|---|---|---|
| Price | 50% | 37 | 37 | 41 |
| Inputs & features | 30% | 70 | 80 | 80 |
| Context window | 20% | 61 | 37 | 60 |
| Overall | 100% | 51/100 | 50/100 | 56/100 |
Left out because at least one model lacks the data: capability. The remaining weights were rescaled.
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | Kimi K2.8 PreviewMoonshot AI | Sakana NamazuSakana AI | Step 5 PreviewStepFun |
|---|---|---|---|
| Capability | |||
| Capabilities Index (ECI) | — | — | — |
| ECI rank | — | — | — |
| Price per million tokens | |||
| Input | $1.00 | $0.95 (best) | $1.00 |
| Output | $4.00 | $4.00 | $2.70 (best) |
| Cached input | — | $0.15 | $0.10 (best) |
| Blended (3:1) | $1.75 | $1.71 | $1.43 (best) |
| Long-context rate | Same rate | Same rate | Same rate |
| Price source | Median of 2 providers | Official Sakana AI API | Official StepFun (Global) API |
| Limits | |||
| Context window | 1,048,576 tokens (best) | 262,144 tokens | 1,000,000 tokens |
| Max output | — | 65,536 tokens | 1,000,000 tokens (best) |
| Inputs and features | |||
| Text | Yes | Yes | Yes |
| Images | Yes | Yes | Yes |
| PDFs | No | Yes | No |
| Audio | No | No | No |
| Video | Yes | No | Yes |
| Reasoning | Yes | Yes | Yeslow · medium · high |
| Tool calling | Yes | Yes | Yes |
| Structured output | No | Yes | Yes |
| Availability | |||
| Weights | Proprietary | Proprietary | Open |
| API model ID | — | sakana-namazu | step-5-preview |
| API providers | 2 | 5 | 18 (best) |
| Released | Sep 11, 2026 | Aug 3, 2026 | Sep 16, 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.
- Kimi K2.8 Preview$18.00
- Sakana Namazu$17.50
- Step 5 Preview$15.40
Which should you choose?
Which is better: Kimi K2.8 Preview, Sakana Namazu or Step 5 Preview?
Step 5 Preview is the better all-round choice, scoring 56/100 against Kimi K2.8 Preview (51) and Sakana Namazu (50). It leads on price. The score weighs price 50%, inputs & features 30%, context window 20%. None of the shared benchmarks cover every model here yet, so capability is left out of this verdict.
Which is cheaper, Kimi K2.8 Preview, Sakana Namazu or Step 5 Preview?
Step 5 Preview is cheaper at $1.00 input / $2.70 output per million tokens (official StepFun (Global) API price). Sakana Namazu costs $0.95 input / $4.00 output per million tokens (official Sakana AI API price); Kimi K2.8 Preview costs $1.00 input / $4.00 output per million tokens (median across 2 API providers). At a typical mix of three input tokens to one output token, that is $1.43 per million tokens for Step 5 Preview versus $1.71 for Sakana Namazu (1.2× as much) and $1.75 for Kimi K2.8 Preview (1.2× as much).
Which scores higher on benchmarks?
There is no independent benchmark that covers all three models yet. Kimi K2.8 Preview has not been scored yet, Sakana Namazu has not been scored yet and Step 5 Preview has not been scored yet.
Which is better for coding?
There are no published SWE-bench Verified results for Kimi K2.8 Preview, Sakana Namazu and Step 5 Preview 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 Step 5 Preview and 262,144 for Sakana Namazu. Maximum output per response: Sakana Namazu up to 65,536, Step 5 Preview up to 1,000,000 tokens.
Which can read images, PDFs, audio or video?
Kimi K2.8 Preview accepts text, images and video; Sakana Namazu accepts text, images and PDFs; Step 5 Preview accepts text, images and video. They handle the same number of input types.
Are any of these open source?
Step 5 Preview publishes its weights and can be self-hosted; Kimi K2.8 Preview and Sakana Namazu is proprietary.
Which is newer?
Step 5 Preview is the newest, released Sep 16, 2026. Kimi K2.8 Preview came out Sep 11, 2026; Sakana Namazu came out Aug 3, 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.
