MiMo-V2.5-Pro-UltraSpeed vs Solar Pro 4 vs Seed 2.1 Pro
Solar Pro 4 comes out ahead, 55 to 50 and 43 on our weighted score, and it is the cheaper option too.
XiaomiMiMo-V2.5-Pro-UltraSpeed
43/100- ECI—
- Price$1.30 / $2.61
- Context1.05M
- Our pick
Upstage
Solar Pro 4
55/100- ECI—
- Price$0.30 / $1.20
- Context524K
ByteDance SeedSeed 2.1 Pro
50/100- ECI—
- Price$0.891 / $4.45
- Context256K
Solar Pro 4 is our pick
Solar Pro 4 is the better all-round choice, scoring 55/100 against Seed 2.1 Pro (50) and MiMo-V2.5-Pro-UltraSpeed (43). It leads on price. MiMo-V2.5-Pro-UltraSpeed wins on context window. Seed 2.1 Pro wins on 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 priceSolar Pro 4Solar Pro 4 $0.525 · 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 · Solar Pro 4 524,288 · Seed 2.1 Pro 256,000 tokens
- Widest inputsSeed 2.1 ProMiMo-V2.5-Pro-UltraSpeed: Text · Solar Pro 4: Text · Seed 2.1 Pro: Text, Images, Video
- Self-hostingMiMo-V2.5-Pro-UltraSpeedPublishes downloadable weights
| Measure | Weight | MiMo-V2.5-Pro-UltraSpeed | Solar Pro 4 | Seed 2.1 Pro |
|---|---|---|---|---|
| Price | 50% | 40 | 63 | 38 |
| Inputs & features | 30% | 35 | 45 | 80 |
| Context window | 20% | 61 | 49 | 36 |
| Overall | 100% | 43/100 | 55/100 | 50/100 |
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 | MiMo-V2.5-Pro-UltraSpeedXiaomi | Solar Pro 4Upstage | Seed 2.1 ProByteDance Seed |
|---|---|---|---|
| Capability | |||
| Capabilities Index (ECI) | — | — | — |
| ECI rank | — | — | — |
| Price per million tokens | |||
| Input | $1.30 | $0.30 (best) | $0.891 |
| Output | $2.61 | $1.20 (best) | $4.45 |
| Cached input | $0.011 (best) | $0.06 | $0.178 |
| Blended (3:1) | $1.63 | $0.525 (best) | $1.78 |
| Long-context rate | Same rate | Same rate | Same rate |
| Price source | Official Xiaomi API | Official Upstage API | Official Volcengine Ark API |
| Limits | |||
| Context window | 1,048,576 tokens (best) | 524,288 tokens | 256,000 tokens |
| Max output | 131,072 tokens | 131,072 tokens | 256,000 tokens (best) |
| Inputs and features | |||
| Text | Yes | Yes | Yes |
| Images | No | No | Yes |
| PDFs | No | No | No |
| Audio | No | No | No |
| Video | No | No | Yes |
| Reasoning | Yes | Yesminimal · low · medium · high · xhigh · max | Yesminimal · low · medium · high · xhigh · max |
| Tool calling | Yes | Yes | Yes |
| Structured output | No | Yes | Yes |
| Availability | |||
| Weights | Open | Proprietary | Proprietary |
| API model ID | mimo-v2.5-pro-ultraspeed | solar-pro4 | doubao-seed-2-1-pro-260628 |
| API providers | 1 | 3 (best) | 2 |
| Released | Jun 8, 2026 | Aug 6, 2026 | Jun 23, 2026 |
| Knowledge cutoff | Dec 2024 | Feb 2026 | — |
What would a month cost?
Enter your expected volume in millions of tokens. List prices only; caching and batch discounts would lower these.
- MiMo-V2.5-Pro-UltraSpeed$18.27
- Solar Pro 4$5.40
- Seed 2.1 Pro$17.81
Which should you choose?
Which is better: MiMo-V2.5-Pro-UltraSpeed, Solar Pro 4 or Seed 2.1 Pro?
Solar Pro 4 is the better all-round choice, scoring 55/100 against Seed 2.1 Pro (50) and MiMo-V2.5-Pro-UltraSpeed (43). It leads on price. MiMo-V2.5-Pro-UltraSpeed wins on context window. Seed 2.1 Pro wins on 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, MiMo-V2.5-Pro-UltraSpeed, Solar Pro 4 or Seed 2.1 Pro?
Solar Pro 4 is cheaper at $0.30 input / $1.20 output per million tokens (official Upstage 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 $0.525 per million tokens for Solar Pro 4 versus $1.63 for MiMo-V2.5-Pro-UltraSpeed (3.1× as much) and $1.78 for Seed 2.1 Pro (3.4× as much).
Which scores higher on benchmarks?
There is no independent benchmark that covers all three models yet. MiMo-V2.5-Pro-UltraSpeed has not been scored yet, Solar Pro 4 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 MiMo-V2.5-Pro-UltraSpeed, Solar Pro 4 and Seed 2.1 Pro 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 524,288 for Solar Pro 4 and 256,000 for Seed 2.1 Pro. Maximum output per response: MiMo-V2.5-Pro-UltraSpeed up to 131,072, Solar Pro 4 up to 131,072, Seed 2.1 Pro up to 256,000 tokens.
Which can read images, PDFs, audio or video?
MiMo-V2.5-Pro-UltraSpeed accepts text; Solar Pro 4 accepts text; Seed 2.1 Pro accepts text, images and video. Seed 2.1 Pro handles the widest range of inputs.
Are any of these open source?
MiMo-V2.5-Pro-UltraSpeed publishes its weights and can be self-hosted; Solar Pro 4 and Seed 2.1 Pro is proprietary.
Which is newer?
Solar Pro 4 is the newest, released Aug 6, 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, Solar Pro 4 Feb 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.
