Solar Pro 4 vs Seed 2.1 Pro
Solar Pro 4 comes out ahead, 55 to 50 on our weighted score, and it is the cheaper option too.
- 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
Add a model
Make it a three-way comparison.
Solar Pro 4 is our pick
Solar Pro 4 is the better all-round choice, scoring 55/100 against Seed 2.1 Pro (50). It leads on price and 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 · Seed 2.1 Pro $1.78 per 1M tokens (3:1 blend)
- Longest contextSolar Pro 4Solar Pro 4 524,288 · Seed 2.1 Pro 256,000 tokens
- Widest inputsSeed 2.1 ProSolar Pro 4: Text · Seed 2.1 Pro: Text, Images, Video
- Self-hostingNo open weightsBoth are available only through APIs
| Measure | Weight | Solar Pro 4 | Seed 2.1 Pro |
|---|---|---|---|
| Price | 50% | 63 | 38 |
| Inputs & features | 30% | 45 | 80 |
| Context window | 20% | 49 | 36 |
| Overall | 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 | Solar Pro 4Upstage | Seed 2.1 ProByteDance Seed |
|---|---|---|
| Capability | ||
| Capabilities Index (ECI) | — | — |
| ECI rank | — | — |
| Price per million tokens | ||
| Input | $0.30 (best) | $0.891 |
| Output | $1.20 (best) | $4.45 |
| Cached input | $0.06 (best) | $0.178 |
| Blended (3:1) | $0.525 (best) | $1.78 |
| Long-context rate | Same rate | Same rate |
| Price source | Official Upstage API | Official Volcengine Ark API |
| Limits | ||
| Context window | 524,288 tokens (best) | 256,000 tokens |
| Max output | 131,072 tokens | 256,000 tokens (best) |
| Inputs and features | ||
| Text | Yes | Yes |
| Images | No | Yes |
| PDFs | No | No |
| Audio | No | No |
| Video | No | Yes |
| Reasoning | Yesminimal · low · medium · high · xhigh · max | Yesminimal · low · medium · high · xhigh · max |
| Tool calling | Yes | Yes |
| Structured output | Yes | Yes |
| Availability | ||
| Weights | Proprietary | Proprietary |
| API model ID | solar-pro4 | doubao-seed-2-1-pro-260628 |
| API providers | 3 (best) | 2 |
| Released | Aug 6, 2026 | Jun 23, 2026 |
| Knowledge cutoff | 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.
- Solar Pro 4$5.40
- Seed 2.1 Pro$17.81
Which should you choose?
Which is better: 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). It leads on price and 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, 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). 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 $1.78 for Seed 2.1 Pro (3.4× as much).
Which scores higher on benchmarks?
There is no independent benchmark that covers both models 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 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. Both support tool calling for agent workflows.
Which has the bigger context window?
Solar Pro 4 has the largest context window at 524,288 tokens, against 256,000 for Seed 2.1 Pro. Maximum output per response: Solar Pro 4 up to 131,072, Seed 2.1 Pro up to 256,000 tokens.
Which can read images, PDFs, audio or video?
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?
No. Solar Pro 4 and Seed 2.1 Pro are proprietary and only available through APIs and apps.
Which is newer?
Solar Pro 4 is the newest, released Aug 6, 2026. Seed 2.1 Pro came out Jun 23, 2026. Knowledge cutoff: 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.
