# Solar Open 2 vs Spark-X2.6-4B

> Side-by-side benchmark comparison for Solar Open 2 and Spark-X2.6-4B across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/solar-open-2-vs-spark-x2-6-4b
- Last updated: October 20, 2026

- Shared sourced benchmarks: 7
- HTML indexing: indexable
- Ranking lane: BenchAlign v5.8

## Quick Verdict

Spark-X2.6-4B leads by point estimate. Conditional score ranges do not establish rank confidence. Choose using the category evidence and your own workload tests.

## Summary

- Spark-X2.6-4B has the higher overall point estimate 40.14 to 0. Conditional score ranges do not establish rank confidence.
- The biggest single benchmark swing is HMMT Feb 2026 in Mathematics, with scores of 93.9% and 81.3%.

## Model Snapshot

| Property | Solar Open 2 | Spark-X2.6-4B |
|----------|----------|----------|
| Creator | Upstage | SparkLLM |
| Type | Open Weight | Open Weight |
| Reasoning | Reasoning | Reasoning |
| Context | 1M | 1M |
| Overall Score | null | 40.14 |
| Benchmarks Covered | 11 | 20 |
| Pricing (input/output) | $0.00 / $0.00 | $0.00 / $0.00 |

## Category Breakdown

### Agentic

- Winner: Not comparable
- Solar Open 2 public-lane score: Coming soon
- Spark-X2.6-4B public-lane score: 33 (Estimated · #89/131)

| Benchmark | Solar Open 2 | Spark-X2.6-4B | Winner |
|-----------|-----------|-----------|--------|
| terminalBenchHard | 28.3% | Coming soon | Coming soon |
| APEX-Agents | 16.6% | Coming soon | Coming soon |
| MCP Atlas | 58.2% | 62.4% | Spark-X2.6-4B |
| BFCL v4 | Coming soon | 71.8% | Coming soon |
| τ²-bench results | Coming soon | 86.9% | Coming soon |
| BrowseComp | Coming soon | 53.1% | Coming soon |
| HLE w/ tools | Coming soon | 36.9% | Coming soon |
| τ³-bench results | Coming soon | 34.7% | Coming soon |
| Claw-Eval | Coming soon | 69.9% | Coming soon |

### Coding

- Winner: Not comparable
- Solar Open 2 public-lane score: Coming soon
- Spark-X2.6-4B public-lane score: 30.6 (Estimated · #95/152)

| Benchmark | Solar Open 2 | Spark-X2.6-4B | Winner |
|-----------|-----------|-----------|--------|
| LiveCodeBench v6 | 92.4% | Coming soon | Coming soon |
| SWE-bench Verified | 70.4% | 62.8% | Solar Open 2 |
| SWE-bench Pro | Coming soon | 54.3% | Coming soon |
| SWE Multilingual | Coming soon | 64.7% | Coming soon |
| SciCode | Coming soon | 36.8% | Coming soon |

### Reasoning

- Winner: Not comparable
- Solar Open 2 public-lane score: Coming soon
- Spark-X2.6-4B public-lane score: 48.8 (Unranked · 2 rankable rows)

| Benchmark | Solar Open 2 | Spark-X2.6-4B | Winner |
|-----------|-----------|-----------|--------|
| LongBench v2 | Coming soon | 53.3% | Coming soon |

### Knowledge

- Winner: Not comparable
- Solar Open 2 public-lane score: Coming soon
- Spark-X2.6-4B public-lane score: 43 (Estimated · #109/187)

| Benchmark | Solar Open 2 | Spark-X2.6-4B | Winner |
|-----------|-----------|-----------|--------|
| MMLU-Pro | 86.2% | Coming soon | Coming soon |
| GPQA-D | 86.3% | 77.1% | Solar Open 2 |
| HLE w/o tools | 28.8% | 17.9% | Solar Open 2 |
| GPQA | Coming soon | 69.9% | Coming soon |

### Instruction Following

- Winner: Not comparable
- Solar Open 2 public-lane score: Coming soon
- Spark-X2.6-4B public-lane score: 78.2 (#62/149)

| Benchmark | Solar Open 2 | Spark-X2.6-4B | Winner |
|-----------|-----------|-----------|--------|
| IFBench | 80% | 75.8% | Solar Open 2 |
| IFEval | Coming soon | 93.6% | Coming soon |

### Mathematics

- Winner: Not comparable
- Solar Open 2 public-lane score: Coming soon
- Spark-X2.6-4B public-lane score: 76.4 (Unranked · 3 rankable rows)

| Benchmark | Solar Open 2 | Spark-X2.6-4B | Winner |
|-----------|-----------|-----------|--------|
| HMMT Feb 2026 | 93.9% | 81.3% | Solar Open 2 |
| AIME26 | 95.7% | 91.2% | Solar Open 2 |
| IMOAnswerBench | Coming soon | 75.2% | Coming soon |

## FAQ

### Which is better overall, Solar Open 2 or Spark-X2.6-4B?

Spark-X2.6-4B has the higher overall point estimate. Conditional score ranges do not establish rank confidence.

### How many benchmarks does Solar Open 2 cover on BenchLM?

Solar Open 2 currently has 11 sourced benchmark scores on BenchLM.

### How many benchmarks does Spark-X2.6-4B cover on BenchLM?

Spark-X2.6-4B currently has 20 sourced benchmark scores on BenchLM.

## Related Comparisons

- [Solar Open 2 vs Claude Opus 5.5](/compare/claude-opus-5-5-vs-solar-open-2)
- [Spark-X2.6-4B vs Claude Opus 5.5](/compare/claude-opus-5-5-vs-spark-x2-6-4b)
- [Solar Open 2 vs GPT-6.1 Sol](/compare/gpt-6-1-sol-vs-solar-open-2)
- [Spark-X2.6-4B vs GPT-6.1 Sol](/compare/gpt-6-1-sol-vs-spark-x2-6-4b)

## Explore More

- [Solar Open 2 profile](/models/solar-open-2)
- [Spark-X2.6-4B profile](/models/spark-x2-6-4b)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)