# Mercury 2.5 vs Spark-X2.6-4B

> Side-by-side benchmark comparison for Mercury 2.5 and Spark-X2.6-4B across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/mercury-2-5-vs-spark-x2-6-4b
- Last updated: October 20, 2026

- Shared sourced benchmarks: 4
- 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 33.94. Conditional score ranges do not establish rank confidence.
- The clearest category separation is in reasoning, where the averages are 71.7 for Mercury 2.5 and 48.8 for Spark-X2.6-4B.
- The biggest single benchmark swing is τ³-bench results in Agentic, with scores of 96.0% and 34.7%.
- Spark-X2.6-4B is the cheaper option on output tokens, which matters if you expect large responses or heavy interactive use.
- Spark-X2.6-4B also has the larger context window at 1M.

## Model Snapshot

| Property | Mercury 2.5 | Spark-X2.6-4B |
|----------|----------|----------|
| Creator | Inception | SparkLLM |
| Type | Proprietary | Open Weight |
| Reasoning | Reasoning | Reasoning |
| Context | 260K | 1M |
| Overall Score | 33.94 | 40.14 |
| Benchmarks Covered | 6 | 20 |
| Pricing (input/output) | $0.04 / $0.15 | $0.00 / $0.00 |

## Category Breakdown

### Agentic

- Winner: Directional only
- Mercury 2.5 public-lane score: 12.2 (Supported · #122/131)
- Spark-X2.6-4B public-lane score: 33 (Estimated · #89/131)

| Benchmark | Mercury 2.5 | Spark-X2.6-4B | Winner |
|-----------|-----------|-----------|--------|
| τ³-bench results | 96.0% | 34.7% | Mercury 2.5 |
| DeepSearchQA | 34.0% | Coming soon | Coming soon |
| Terminal-Bench 2.1 (Vals) | 34.5% | Coming soon | Coming soon |
| BFCL v4 | Coming soon | 71.8% | Coming soon |
| τ²-bench results | Coming soon | 86.9% | Coming soon |
| MCP Atlas | Coming soon | 62.4% | Coming soon |
| BrowseComp | Coming soon | 53.1% | Coming soon |
| HLE w/ tools | Coming soon | 36.9% | Coming soon |
| Claw-Eval | Coming soon | 69.9% | Coming soon |

### Coding

- Winner: Directional only
- Mercury 2.5 public-lane score: 16.1 (Estimated · #132/152)
- Spark-X2.6-4B public-lane score: 30.6 (Estimated · #95/152)

| Benchmark | Mercury 2.5 | Spark-X2.6-4B | Winner |
|-----------|-----------|-----------|--------|
| SciCode | 38% | 36.8% | Mercury 2.5 |
| SWE-bench Pro | Coming soon | 54.3% | Coming soon |
| SWE-bench Verified | Coming soon | 62.8% | Coming soon |
| SWE Multilingual | Coming soon | 64.7% | Coming soon |

### Reasoning

- Winner: Not comparable
- Mercury 2.5 public-lane score: 71.7 (Unranked · 2 rankable rows)
- Spark-X2.6-4B public-lane score: 48.8 (Unranked · 2 rankable rows)

| Benchmark | Mercury 2.5 | Spark-X2.6-4B | Winner |
|-----------|-----------|-----------|--------|
| LongBench v2 | Coming soon | 53.3% | Coming soon |

### Knowledge

- Winner: Directional only
- Mercury 2.5 public-lane score: 34.4 (Supported · #139/187)
- Spark-X2.6-4B public-lane score: 43 (Estimated · #109/187)

| Benchmark | Mercury 2.5 | Spark-X2.6-4B | Winner |
|-----------|-----------|-----------|--------|
| GPQA-D | 79.0% | 77.1% | Mercury 2.5 |
| HLE w/o tools | Coming soon | 17.9% | Coming soon |
| GPQA | Coming soon | 69.9% | Coming soon |

### Instruction Following

- Winner: Mercury 2.5
- Mercury 2.5 public-lane score: 81.1 (#58/149)
- Spark-X2.6-4B public-lane score: 78.2 (#62/149)

| Benchmark | Mercury 2.5 | Spark-X2.6-4B | Winner |
|-----------|-----------|-----------|--------|
| IFBench | 77% | 75.8% | Mercury 2.5 |
| IFEval | Coming soon | 93.6% | Coming soon |

### Mathematics

- Winner: Not comparable
- Mercury 2.5 public-lane score: Coming soon
- Spark-X2.6-4B public-lane score: 76.4 (Unranked · 3 rankable rows)

| Benchmark | Mercury 2.5 | Spark-X2.6-4B | Winner |
|-----------|-----------|-----------|--------|
| AIME26 | Coming soon | 91.2% | Coming soon |
| HMMT Feb 2026 | Coming soon | 81.3% | Coming soon |
| IMOAnswerBench | Coming soon | 75.2% | Coming soon |

## FAQ

### Which is better overall, Mercury 2.5 or Spark-X2.6-4B?

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

### Where is the biggest gap between Mercury 2.5 and Spark-X2.6-4B?

The widest category gap is in reasoning, where the averages are 71.7 for Mercury 2.5 and 48.8 for Spark-X2.6-4B.

### How many benchmarks does Mercury 2.5 cover on BenchLM?

Mercury 2.5 currently has 6 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

- [Mercury 2.5 vs Mercury 2.5 Preview](/compare/mercury-2-5-vs-mercury-2-5-preview)
- [Spark-X2.6-4B vs Mercury 2.5 Preview](/compare/mercury-2-5-preview-vs-spark-x2-6-4b)
- [Mercury 2.5 vs Claude Opus 5.5](/compare/claude-opus-5-5-vs-mercury-2-5)
- [Spark-X2.6-4B vs Claude Opus 5.5](/compare/claude-opus-5-5-vs-spark-x2-6-4b)

## Explore More

- [Mercury 2.5 profile](/models/mercury-2-5)
- [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)