Kimi K2.8 Preview vs Seed 2.1 Pro
Too close to call on our weighted score (Kimi K2.8 Preview 51, Seed 2.1 Pro 49). The right pick depends on what you value most.
Moonshot AIKimi K2.8 Preview
51/100- ECI—
- Price$1.00 / $4.00
- Context1.05M
ByteDance SeedSeed 2.1 Pro
49/100- ECI—
- Price$0.891 / $4.45
- Context256K
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Make it a three-way comparison.
Too close to call
It is close. Our weighted score puts them within 2 points (Kimi K2.8 Preview 51/100, Seed 2.1 Pro 49/100), so choose by what matters most for your work: Kimi K2.8 Preview on price and Kimi K2.8 Preview for long inputs. 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 priceKimi K2.8 PreviewKimi K2.8 Preview $1.75 · Seed 2.1 Pro $1.78 per 1M tokens (3:1 blend)
- Longest contextKimi K2.8 PreviewKimi K2.8 Preview 1,048,576 · Seed 2.1 Pro 256,000 tokens
- Widest inputsSame inputsKimi K2.8 Preview: Text, Images, Video · Seed 2.1 Pro: Text, Images, Video
- Self-hostingNo open weightsBoth are available only through APIs
| Measure | Weight | Kimi K2.8 Preview | Seed 2.1 Pro |
|---|---|---|---|
| Price | 50% | 37 | 36 |
| Inputs & features | 30% | 70 | 80 |
| Context window | 20% | 61 | 36 |
| Overall | 100% | 51/100 | 49/100 |
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 | Seed 2.1 ProByteDance Seed |
|---|---|---|
| Capability | ||
| Capabilities Index (ECI) | — | — |
| ECI rank | — | — |
| Price per million tokens | ||
| Input | $1.00 | $0.891 (best) |
| Output | $4.00 (best) | $4.45 |
| Cached input | — | $0.178 |
| Blended (3:1) | $1.75 (best) | $1.78 |
| Long-context rate | Same rate | Same rate |
| Price source | Median of 2 providers | Official Volcengine Ark API |
| Limits | ||
| Context window | 1,048,576 tokens (best) | 256,000 tokens |
| Max output | — | 256,000 tokens |
| Inputs and features | ||
| Text | Yes | Yes |
| Images | Yes | Yes |
| PDFs | No | No |
| Audio | No | No |
| Video | Yes | Yes |
| Reasoning | Yes | Yesminimal · low · medium · high · xhigh · max |
| Tool calling | Yes | Yes |
| Structured output | No | Yes |
| Availability | ||
| Weights | Proprietary | Proprietary |
| API model ID | — | doubao-seed-2-1-pro-260628 |
| API providers | 2 | 3 (best) |
| Released | Sep 11, 2026 | Jun 23, 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
- Seed 2.1 Pro$17.81
Which should you choose?
Which is better: Kimi K2.8 Preview or Seed 2.1 Pro?
It is close. Our weighted score puts them within 2 points (Kimi K2.8 Preview 51/100, Seed 2.1 Pro 49/100), so choose by what matters most for your work: Kimi K2.8 Preview on price and Kimi K2.8 Preview for long inputs. 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 or Seed 2.1 Pro?
Kimi K2.8 Preview is cheaper at $1.00 input / $4.00 output per million tokens (median across 2 API providers). Seed 2.1 Pro costs $0.891 input / $4.45 output per million tokens (official Volcengine Ark API price). At a typical mix of three input tokens to one output token, that is $1.75 per million tokens for Kimi K2.8 Preview versus $1.78 for Seed 2.1 Pro (1× as much).
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 Seed 2.1 Pro has not been scored yet.
Which is better for coding?
There are no published SWE-bench Verified results for Kimi K2.8 Preview and Seed 2.1 Pro 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 256,000 for Seed 2.1 Pro. Maximum output per response: Seed 2.1 Pro up to 256,000 tokens.
Which can read images, PDFs, audio or video?
Kimi K2.8 Preview accepts text, images and video; Seed 2.1 Pro 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 Seed 2.1 Pro are proprietary and only available through APIs and apps.
Which is newer?
Kimi K2.8 Preview is the newest, released Sep 11, 2026. Seed 2.1 Pro came out Jun 23, 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.
