# Solar Pro 4

> Solar Pro 4 is a proprietary language model from Upstage, released on 6 Aug 2026. It accepts text and generates text, with a 524K-token context window and up to 131K output tokens per response. As of 4 Oct 2026, the lowest listed API price is $0.09 per million input tokens and $0.36 per million output tokens (OpenRouter), across 2 providers we track.

Source page: https://www.aimodel.directory/models/solar-pro4
Last verified: 4 Oct 2026

## Specifications

- **Developer:** Upstage
- **Release date:** 6 Aug 2026 (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/upstage/models/solar-pro4.toml)
- **Status:** Generally available (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/upstage/models/solar-pro4.toml)
- **Weights:** Proprietary (API only) (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/upstage/models/solar-pro4.toml)
- **Context window:** 524K (524,288 tokens) (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/upstage/models/solar-pro4.toml)
- **Max output:** 131K tokens (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/upstage/models/solar-pro4.toml)
- **Knowledge cutoff:** Feb 2026 (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/upstage/models/solar-pro4.toml)
- **Input:** Text (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/upstage/models/solar-pro4.toml)
- **Output:** Text (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/upstage/models/solar-pro4.toml)
- **Reasoning mode:** Yes (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/upstage/models/solar-pro4.toml)
- **Tool calling:** Yes (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/upstage/models/solar-pro4.toml)
- **Structured output:** Yes (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/upstage/models/solar-pro4.toml)

## API pricing (USD per 1M tokens)

| Provider | Input | Output | Cached input | Context |
|---|---|---|---|---|
| OpenRouter | $0.09 | $0.36 | $0.02 | 524K |
| Upstage Console | $0.30 | $1.20 | $0.06 | 524K |

## FAQ

### What is the context window of Solar Pro 4?

Solar Pro 4 has a context window of 524,288 tokens (524K) and can generate up to 131,072 tokens in a single response, according to models.dev.

### How much does the Solar Pro 4 API cost?

Through Upstage Console, Solar Pro 4 costs $0.30 per million input tokens and $1.20 per million output tokens. The lowest listed price is $0.09 input / $0.36 output through OpenRouter. Prices last verified 4 Oct 2026.

### Is Solar Pro 4 open source?

No. Solar Pro 4 is a proprietary model; Upstage has not released its weights. It is available through APIs including OpenRouter, Upstage Console.

### When was Solar Pro 4 released?

Upstage released Solar Pro 4 on 6 Aug 2026, according to models.dev.

### Which providers offer Solar Pro 4?

We track Solar Pro 4 on 2 providers: OpenRouter, Upstage Console.

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Data licensed CC BY 4.0. Cite as: AI Model Directory, "Solar Pro 4", https://www.aimodel.directory/models/solar-pro4