Kimi K2.8 Preview vs Step 5 Preview
Step 5 Preview comes out ahead, 72 to 66 on our weighted score, and it is the cheaper option too.
Moonshot AIKimi K2.8 Preview
66/100- ECI—
- Price—
- Context1.05M
- Our pick
StepFunStep 5 Preview
72/100- ECI—
- Price$1.00 / $2.70
- Context1M
Add a model
Make it a three-way comparison.
Step 5 Preview is our pick
Step 5 Preview 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 priceStep 5 PreviewStep 5 Preview $1.43 per 1M tokens (3:1 blend) · Kimi K2.8 Preview unpriced
- Longest contextKimi K2.8 PreviewKimi K2.8 Preview 1,048,576 · Step 5 Preview 1,000,000 tokens
- Widest inputsSame inputsKimi K2.8 Preview: Text, Images, Video · Step 5 Preview: Text, Images, Video
- Self-hostingNo open weightsBoth are available only through APIs
| Measure | Weight | Kimi K2.8 Preview | Step 5 Preview |
|---|---|---|---|
| Inputs & features | 60% | 70 | 80 |
| Context window | 40% | 61 | 60 |
| Overall | 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 | Kimi K2.8 PreviewMoonshot AI | Step 5 PreviewStepFun |
|---|---|---|
| Capability | ||
| Capabilities Index (ECI) | — | — |
| ECI rank | — | — |
| Price per million tokens | ||
| Input | — | $1.00 |
| Output | — | $2.70 |
| Cached input | — | $0.05 |
| Blended (3:1) | — | $1.43 |
| Long-context rate | — | Same rate |
| Price source | — | Official StepFun (Global) API |
| Limits | ||
| Context window | 1,048,576 tokens (best) | 1,000,000 tokens |
| Max output | — | 1,000,000 tokens |
| Inputs and features | ||
| Text | Yes | Yes |
| Images | Yes | Yes |
| PDFs | No | No |
| Audio | No | No |
| Video | Yes | Yes |
| Reasoning | Yes | Yeslow · medium · high |
| Tool calling | Yes | Yes |
| Structured output | No | Yes |
| Availability | ||
| Weights | Proprietary | Proprietary |
| API model ID | — | step-5-preview |
| API providers | — | 7 |
| Released | Sep 11, 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—
- Step 5 Preview$15.40
Which should you choose?
Which is better: Kimi K2.8 Preview or Step 5 Preview?
Step 5 Preview 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, Kimi K2.8 Preview or Step 5 Preview?
Step 5 Preview is cheaper at $1.00 input / $2.70 output per million tokens (official StepFun (Global) API price). . At a typical mix of three input tokens to one output token, that is $1.43 per million tokens for Step 5 Preview 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. Kimi K2.8 Preview 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 and Step 5 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?
Kimi K2.8 Preview has the largest context window at 1,048,576 tokens, against 1,000,000 for Step 5 Preview. Maximum output per response: 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; Step 5 Preview accepts text, images and video. They handle the same number of input types.
Are any of these open source?
No. Kimi K2.8 Preview and Step 5 Preview are proprietary and only available through APIs and apps.
Which is newer?
Step 5 Preview is the newest, released Sep 16, 2026. Kimi K2.8 Preview came out Sep 11, 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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