Step 5 Preview vs Kimi K2.8 Preview
Step 5 Preview comes out ahead, 56 to 51 on our weighted score, and it is the cheaper option too.
- Our pick
StepFunStep 5 Preview
56/100- ECI—
- Price$1.00 / $2.70
- Context1M
Moonshot AIKimi K2.8 Preview
51/100- ECI—
- Price$1.00 / $4.00
- Context1.05M
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Make it a three-way comparison.
Step 5 Preview is our pick
Step 5 Preview is the better all-round choice, scoring 56/100 against Kimi K2.8 Preview (51). It leads on price and inputs & features. 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 · 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 tokens
- Widest inputsSame inputsStep 5 Preview: Text, Images, Video · Kimi K2.8 Preview: Text, Images, Video
- Self-hostingStep 5 PreviewPublishes downloadable weights
| Measure | Weight | Step 5 Preview | Kimi K2.8 Preview |
|---|---|---|---|
| Price | 50% | 41 | 37 |
| Inputs & features | 30% | 80 | 70 |
| Context window | 20% | 60 | 61 |
| Overall | 100% | 56/100 | 51/100 |
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 | Step 5 PreviewStepFun | Kimi K2.8 PreviewMoonshot AI |
|---|---|---|
| Capability | ||
| Capabilities Index (ECI) | — | — |
| ECI rank | — | — |
| Price per million tokens | ||
| Input | $1.00 | $1.00 |
| Output | $2.70 (best) | $4.00 |
| Cached input | $0.10 | — |
| Blended (3:1) | $1.43 (best) | $1.75 |
| Long-context rate | Same rate | Same rate |
| Price source | Official StepFun (Global) API | Median of 2 providers |
| Limits | ||
| Context window | 1,000,000 tokens | 1,048,576 tokens (best) |
| 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 | Yeslow · medium · high | Yes |
| Tool calling | Yes | Yes |
| Structured output | Yes | No |
| Availability | ||
| Weights | Open | Proprietary |
| API model ID | step-5-preview | — |
| API providers | 18 (best) | 2 |
| Released | Sep 16, 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.
- Step 5 Preview$15.40
- Kimi K2.8 Preview$18.00
Which should you choose?
Which is better: Step 5 Preview or Kimi K2.8 Preview?
Step 5 Preview is the better all-round choice, scoring 56/100 against Kimi K2.8 Preview (51). It leads on price and inputs & features. 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, Step 5 Preview or Kimi K2.8 Preview?
Step 5 Preview is cheaper at $1.00 input / $2.70 output per million tokens (official StepFun (Global) 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 $1.75 for Kimi K2.8 Preview (1.2× as much).
Which scores higher on benchmarks?
There is no independent benchmark that covers both models yet. Step 5 Preview 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 Step 5 Preview 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?
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?
Step 5 Preview accepts text, images and video; Kimi K2.8 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 is proprietary.
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 Nov 2, 2026.
