Seed 2.1 Pro vs Hy4 preview vs MiMo-V2.5-Pro-UltraSpeed
Seed 2.1 Pro comes out ahead, 50 to 45 and 43 on our weighted score, though Hy4 preview is 30% cheaper per token.
- Our pick
ByteDance SeedSeed 2.1 Pro
50/100- ECI—
- Price$0.891 / $4.45
- Context256K
TencentHy4 preview
45/100- ECI—
- Price$0.834 / $2.50
- Context1.02M
XiaomiMiMo-V2.5-Pro-UltraSpeed
43/100- ECI—
- Price$1.30 / $2.61
- Context1.05M
Seed 2.1 Pro is our pick
Seed 2.1 Pro is the better all-round choice, scoring 50/100 against Hy4 preview (45) and MiMo-V2.5-Pro-UltraSpeed (43). It leads on inputs & features. Hy4 preview wins 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 priceHy4 previewHy4 preview $1.25 · MiMo-V2.5-Pro-UltraSpeed $1.63 · Seed 2.1 Pro $1.78 per 1M tokens (3:1 blend)
- Longest contextMiMo-V2.5-Pro-UltraSpeedMiMo-V2.5-Pro-UltraSpeed 1,048,576 · Hy4 preview 1,024,000 · Seed 2.1 Pro 256,000 tokens
- Widest inputsSeed 2.1 ProSeed 2.1 Pro: Text, Images, Video · Hy4 preview: Text · MiMo-V2.5-Pro-UltraSpeed: Text
- Self-hostingHy4 preview and MiMo-V2.5-Pro-UltraSpeedPublishes downloadable weights
| Measure | Weight | Seed 2.1 Pro | Hy4 preview | MiMo-V2.5-Pro-UltraSpeed |
|---|---|---|---|---|
| Price | 50% | 38 | 45 | 40 |
| Inputs & features | 30% | 80 | 35 | 35 |
| Context window | 20% | 36 | 60 | 61 |
| Overall | 100% | 50/100 | 45/100 | 43/100 |
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 | Seed 2.1 ProByteDance Seed | Hy4 previewTencent | MiMo-V2.5-Pro-UltraSpeedXiaomi |
|---|---|---|---|
| Capability | |||
| Capabilities Index (ECI) | — | — | — |
| ECI rank | — | — | — |
| Price per million tokens | |||
| Input | $0.891 | $0.834 (best) | $1.30 |
| Output | $4.45 | $2.50 (best) | $2.61 |
| Cached input | $0.178 | $0.042 | $0.011 (best) |
| Blended (3:1) | $1.78 | $1.25 (best) | $1.63 |
| Long-context rate | Same rate | Same rate | Same rate |
| Price source | Official Volcengine Ark API | Official Tencent TokenHub API | Official Xiaomi API |
| Limits | |||
| Context window | 256,000 tokens | 1,024,000 tokens | 1,048,576 tokens (best) |
| Max output | 256,000 tokens (best) | 64,000 tokens | 131,072 tokens |
| Inputs and features | |||
| Text | Yes | Yes | Yes |
| Images | Yes | No | No |
| PDFs | No | No | No |
| Audio | No | No | No |
| Video | Yes | No | No |
| Reasoning | Yesminimal · low · medium · high · xhigh · max | Yeshigh | Yes |
| Tool calling | Yes | Yes | Yes |
| Structured output | Yes | No | No |
| Availability | |||
| Weights | Proprietary | Open | Open |
| API model ID | doubao-seed-2-1-pro-260628 | hy4-preview | mimo-v2.5-pro-ultraspeed |
| API providers | 2 | 13 (best) | 1 |
| Released | Jun 23, 2026 | Aug 28, 2026 | Jun 8, 2026 |
| Knowledge cutoff | — | — | Dec 2024 |
What would a month cost?
Enter your expected volume in millions of tokens. List prices only; caching and batch discounts would lower these.
- Seed 2.1 Pro$17.81
- Hy4 preview$13.34
- MiMo-V2.5-Pro-UltraSpeed$18.27
Which should you choose?
Which is better: Seed 2.1 Pro, Hy4 preview or MiMo-V2.5-Pro-UltraSpeed?
Seed 2.1 Pro is the better all-round choice, scoring 50/100 against Hy4 preview (45) and MiMo-V2.5-Pro-UltraSpeed (43). It leads on inputs & features. Hy4 preview wins 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, Seed 2.1 Pro, Hy4 preview or MiMo-V2.5-Pro-UltraSpeed?
Hy4 preview is cheaper at $0.834 input / $2.50 output per million tokens (official Tencent TokenHub API price). MiMo-V2.5-Pro-UltraSpeed costs $1.30 input / $2.61 output per million tokens (official Xiaomi API price); 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 $1.25 per million tokens for Hy4 preview versus $1.63 for MiMo-V2.5-Pro-UltraSpeed (1.3× as much) and $1.78 for Seed 2.1 Pro (1.4× as much).
Which scores higher on benchmarks?
There is no independent benchmark that covers all three models yet. Seed 2.1 Pro has not been scored yet, Hy4 preview has not been scored yet and MiMo-V2.5-Pro-UltraSpeed has not been scored yet.
Which is better for coding?
There are no published SWE-bench Verified results for Seed 2.1 Pro, Hy4 preview and MiMo-V2.5-Pro-UltraSpeed 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?
MiMo-V2.5-Pro-UltraSpeed has the largest context window at 1,048,576 tokens, against 1,024,000 for Hy4 preview and 256,000 for Seed 2.1 Pro. Maximum output per response: Seed 2.1 Pro up to 256,000, Hy4 preview up to 64,000, MiMo-V2.5-Pro-UltraSpeed up to 131,072 tokens.
Which can read images, PDFs, audio or video?
Seed 2.1 Pro accepts text, images and video; Hy4 preview accepts text; MiMo-V2.5-Pro-UltraSpeed accepts text. Seed 2.1 Pro handles the widest range of inputs.
Are any of these open source?
Hy4 preview and MiMo-V2.5-Pro-UltraSpeed publishes its weights and can be self-hosted; Seed 2.1 Pro is proprietary.
Which is newer?
Hy4 preview is the newest, released Aug 28, 2026. Seed 2.1 Pro came out Jun 23, 2026; MiMo-V2.5-Pro-UltraSpeed came out Jun 8, 2026. Knowledge cutoff: MiMo-V2.5-Pro-UltraSpeed Dec 2024.
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.
