Meta's Muse Spark 1.3 Hits #4 on LiveBench at $0.22 per Task
Muse Spark 1.3, from Meta, has entered the September 2026 LiveBench leaderboard at fourth place overall with a score of 81.6 — putting it ahead of every Google model in the general ranking, and within 1.8 points of the leader, Claude Fable 5.1.
Its cost-per-successful-task is $0.219, running xHigh Effort. That is less than a fifth of Claude Fable 5.1’s $1.212, and roughly a third of GPT-6 Astra’s $0.736.
Where It Sits in the Top 5
The September 2026 LiveBench top 5:
| Model | Overall | Agentic Coding | Cost/Task |
|---|---|---|---|
| Claude Fable 5.1 (max) | 83.4 | 66.1 | $1.212 |
| Claude Fable 5 (max) | 83.0 | 62.2 | $1.439 |
| GPT-6 Astra (max) | 82.2 | 57.3 | $0.736 |
| Muse Spark 1.3 (xHigh) | 81.6 | 64.1 | $0.219 |
| DeepSeek V4.1 Flash (max) | 81.1 | 77.3 | $0.029 |
Muse Spark 1.3’s 81.6 puts it 0.6 points behind GPT-6 Astra in the overall standings, but ahead of every Google model in the ranking.
Category Breakdown
The model scores 89.7 on Reasoning, matching Claude Fable 5. GPT-6 Astra leads on Reasoning at 92.7 — the one category where OpenAI holds the top position. In Mathematics it hits 95.9, in Coding 81.1, in Language 82.8, and in Instruction Following 78.0.
Its Agentic Coding score of 64.1 places it third among paid frontier models behind Fable 5.1 (66.1) and Claude Opus 5 Thinking (65.2) — well ahead of GPT-6 Astra’s 57.3 and Fable 5’s 62.2. Only DeepSeek V4.1 Flash (77.3) scores higher on that specific column, but Flash is open-weight and costs $0.029/task.
Cost-Performance Context
The case for Muse Spark 1.3 is largely economic. A customer running at scale who does not need Anthropic’s Agentic Coding edge (Fable 5.1 leads by 2 points on that column) can get comparable overall performance for roughly one-fifth the inference cost.
The gap between Muse Spark 1.3 (81.6, $0.219) and Claude Fable 5.1 (83.4, $1.212) is 1.8 LiveBench points and 5.5x in cost. Whether that tradeoff is worthwhile depends on the task mix, but at high volume the arithmetic is significant.
Lab Context
Meta appears in LiveBench’s organizational filter alongside Anthropic, OpenAI, Google, DeepSeek, and xAI. Muse Spark 1.3 was also added to the Arena.ai leaderboard in the September 8 update, per the Arena changelog, alongside GPT-6 Astra Max and the ChatGPT Images 2.5 generation.
The model has not been subject to independent SWE-bench Verified or tau-bench evaluation as of this writing. Its LiveBench scores are the primary external signal available. Agentic capability scoring on the Stack Futures ticker remains pending until primary benchmark data arrives.