Model comparison
Muse Spark 1.3 vs Upstage Solar Pro 4
Meta against Upstage, compared on context, price, and verified benchmark results.
Catalog record checked September 5, 2026Individual provider fields may changeEvidence confidence: Medium — see receipts below
Meta
Muse Spark 1.3
Frontier
Upstage
Upstage Solar Pro 4
Frontier
| Specification | Muse Spark 1.3 | Upstage Solar Pro 4 |
|---|---|---|
| Provider | Meta | Upstage |
| Tier | Frontier | Frontier |
| Context window | Winner: 1M | 524K |
| Max output | 131K | Not verifiedUnverified |
| Input / 1M tokens | $1.25 | Winner: $0.30 |
| Output / 1M tokens | $4.25 | Winner: $1.20 |
| Weights | Closed | Closed |
| Parameters | Meta frontier model | Not disclosedUnverified |
| Reasoning levels | low, medium, high | low, medium, high |
| Modalities | text, image | text |
| API model id | muse-spark-1.3 | solar-pro-4 |
| Released | September 2, 2026 | August 10, 2026 |
| DeepSWE 1.1 (2026-09-02) | 75.4 | Not verifiedUnverified |
| Terminal-Bench 2.1 (2026-09-03) | 88.8 | Not verifiedUnverified |
| Artificial Analysis Intelligence Index (2026-08-14) | Not verifiedUnverified | 50 |
Prices are USD per million tokens at standard rates, excluding batch and caching discounts. Bold indicates the better figure where one is objectively better. Values we could not confirm from the provider are shown as “Not verified” rather than estimated.
Benchmark receipts
- 2026-09-03: Meta launch table (transcribed by explainx.ai) (Vendor self-report; absent from the official tbench.ai leaderboard)Agentic terminal work: multi-step tasks executed in a sandboxed shell environment. Comparability: comparable with caveat — Scores across Terminal-Bench major versions (v1 vs v2) are NOT comparable; harness configuration (container, time limits) also shifts results.
- 2026-09-02: Meta launch table (Thinking mode: max — self-reported; not broadly available and NOT on the official Datacurve leaderboard)Agentic software engineering: pass@1 on real repo tasks with reported cost per completed task. Comparability: directly comparable
- 2026-08-14: Artificial AnalysisComposite index blending reasoning, knowledge, and coding evals into one 0–100 score. Comparability: directly comparable — AA occasionally rebaselines the index scale between snapshots — a score captured on one date is only comparable to same-snapshot scores (check measuredAt).
Pricing tiers: Muse Spark 1.3: $1.25/$4.25 per MTok on Meta's Model API (cached input $0.15); a $0.10/$0.20 'contributor' tier applies when your data is used for training. Third-party reports put list at $1.50/$7.50 from 2027-01-01 — confirm before long-term commits. · Upstage Solar Pro 4: List $0.30/$1.20 per MTok; live promo rate is $0.03/$0.12 (90% off through 2026-09-10). Closed API. 524K context.
Muse Spark 1.3
Muse Spark 1.3 is Meta's September 2026 frontier refresh — a self-reported DeepSWE 1.1 field leader at $1.25/$4.25, with a 1M-token context aimed at autonomous agent workflows.
Best for
- Long-horizon coding agents
- Frontier quality below frontier pricing
- Meta ecosystem
Watch out
The headline 75.4% DeepSWE score comes from the 'max' thinking mode, which is not broadly available yet and is pending independent verification. The 131,072 output cap is per third-party API docs — Meta's own spec page does not publish it. Closed weights, unlike Muse Spark 1.1.
Upstage Solar Pro 4
Solar Pro 4 is Upstage's closed flagship with a 524K context at a low launch price.
Best for
- Long-context
- Cost-sensitive API
- Korean + English
Watch out
Closed API; promo pricing may end.
When the cheaper one wins
Upstage Solar Pro 4 is cheaper on output at $1.20 per million tokens against $4.25 for Muse Spark 1.3 — about 3.5×. Use the cheaper tier for classification, extraction, summarisation, and any task where the expensive model’s extra score does not change the accepted output. The expensive one only pays if your hardest task actually fails on the cheap tier. These are standard-tier API rates, excluding batch and cache discounts.
Run the model pickerEvidence confidence: Medium
How strong and complete the evidence behind this comparison is — not a prediction of which model is better.
- Pricing verified on both sides — Input and output rates are verified for both models.
- 3/5 core specs verified on both sides — Not published for at least one side: max output, parameter count.
- No shared named benchmark — No benchmark has been measured on both models.
- Verified within the last 90 days — Newest catalog check was 6 days ago.
- Both models carry source citations — Each side has at least two catalog sources on record.
Source receipts
Each catalog figure was checked against the provider or an independent second source on the date shown.
- Muse Spark 1.3: Meta — Introducing Muse Spark 1.3 (accessed 2026-09-03)
- Muse Spark 1.3: Meta developer — Muse Spark pricing ($1.25/$4.25) (accessed 2026-09-03)
- Muse Spark 1.3: VentureBeat — Muse Spark 1.3 best results need a config developers can't broadly use yet (accessed 2026-09-03)
- Muse Spark 1.3: HaiMaker — muse-spark-1.3 (131,072 max output tokens) (accessed 2026-09-05)
- Muse Spark 1.3: Promptfoo — Meta provider docs (muse-spark-1.3 max_tokens ceiling) (accessed 2026-09-05)
- Upstage Solar Pro 4: Upstage — Solar Pro 4 (accessed 2026-08-29)
- Upstage Solar Pro 4: Upstage (accessed 2026-08-29)
Related comparisons
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- Claude Fable 5.1 vs Upstage Solar Pro 4
- Claude Fable 5 vs Muse Spark 1.3
- Claude Fable 5 vs Upstage Solar Pro 4
- Claude Mythos 5.1 vs Muse Spark 1.3
- Claude Mythos 5.1 vs Upstage Solar Pro 4
Diving deeper on one model? Muse Spark 1.3 · Upstage Solar Pro 4
Common questions
Muse Spark 1.3 vs Upstage Solar Pro 4
Answered from the verified figures on this page rather than general guidance.
Is Muse Spark 1.3 or Upstage Solar Pro 4 cheaper for input?
Upstage Solar Pro 4 is cheaper at $0.30 per million input tokens, against $1.25 for Muse Spark 1.3 — roughly 4.2× the price. Output tokens usually dominate a real bill, so weigh the output rate more heavily than the input rate. These are base rates; Muse Spark 1.3 has tiered pricing: $1.25/$4.25 per MTok on Meta's Model API (cached input $0.15); a $0.10/$0.20 'contributor' tier applies when your data is used for training. Third-party reports put list at $1.50/$7.50 from 2027-01-01 — confirm before long-term commits. Upstage Solar Pro 4 has tiered pricing: List $0.30/$1.20 per MTok; live promo rate is $0.03/$0.12 (90% off through 2026-09-10). Closed API. 524K context.
Is Muse Spark 1.3 or Upstage Solar Pro 4 cheaper for output?
Upstage Solar Pro 4 is cheaper at $1.20 per million output tokens, against $4.25 for Muse Spark 1.3 — roughly 3.5× the price. Output tokens usually dominate a real bill, so weigh the output rate more heavily than the input rate. These are base rates; Muse Spark 1.3 has tiered pricing: $1.25/$4.25 per MTok on Meta's Model API (cached input $0.15); a $0.10/$0.20 'contributor' tier applies when your data is used for training. Third-party reports put list at $1.50/$7.50 from 2027-01-01 — confirm before long-term commits. Upstage Solar Pro 4 has tiered pricing: List $0.30/$1.20 per MTok; live promo rate is $0.03/$0.12 (90% off through 2026-09-10). Closed API. 524K context.
Which has the larger context window, Muse Spark 1.3 or Upstage Solar Pro 4?
Muse Spark 1.3 accepts 1M tokens against 524K for Upstage Solar Pro 4. This only matters if you routinely send very long documents or large codebases.
Do Muse Spark 1.3 and Upstage Solar Pro 4 support the same reasoning levels?
Yes — both accept the same effort settings: "low", "medium", "high". Higher effort costs more and takes longer, so start low and raise it only where output quality actually improves.
Should I use Muse Spark 1.3 or Upstage Solar Pro 4?
Both sit in the frontier tier, so the choice usually comes down to price and context rather than capability. Muse Spark 1.3 suits long-horizon coding agents; Upstage Solar Pro 4 suits long-context.
Next step
Choosing between them
The verified figures that separate this pair, computed from the catalog rather than restated boilerplate.
- Input price: Upstage Solar Pro 4 costs $0.30 per 1M tokens versus $1.25 for Muse Spark 1.3 — a 4.2x difference at the headline tier.
- Context: Muse Spark 1.3 takes 1M against 524K for Upstage Solar Pro 4 — only decisive if your prompts approach the smaller window.
Choosing a harness rather than a model — Cursor, Copilot, Claude Code, Windsurf, or Lovable? Compare agentic harnesses · Latest releases.