GPT-6 Luna vs Muse Spark 1.3.
Verdict by category, tale of the tape, shared benchmarks only, and cost at three workloads — all from the tracked data.
Verdict by category
| Category | GPT-6 Luna | Muse Spark 1.3 | Winner |
|---|---|---|---|
| League Score | 55.1 | 51.7 | GPT-6 Luna |
| Coding (SWE-bench %) | — | — | — |
| Reasoning (GPQA %) | — | — | — |
| Context (tokens) | 1050000 | 1048576 | GPT-6 Luna |
| Speed (tok/s) | — | — | — |
| Price (blended $/1M) | $0.20 | $2.00 | GPT-6 Luna (cheaper) |
Tale of the tape
| Spec | GPT-6 Luna | Muse Spark 1.3 |
|---|---|---|
| Maker | OpenAI | Meta |
| Released | Sep 22, 2026 | Sep 2, 2026 |
| League Score | 55 | 52 |
| Context | 1,050,000 tokens | 1,048,576 tokens |
| Max output | 128,000 | 943,718 |
| $/1M input | $0.10 | $1.25 |
| $/1M output | $0.50 | $4.25 |
| Weights | Closed | Closed |
| Speed | — | — |
Head-to-head benchmarks (shared only)
| Benchmark | GPT-6 Luna | Muse Spark 1.3 |
|---|---|---|
| LiveBench overall | 64.6 | 63.0 |
Cost at three workloads
| Workload | GPT-6 Luna | Muse Spark 1.3 |
|---|---|---|
| Light — 1M in / 250K out | $0.23 | $2.31 |
| Standard — 10M in / 2.5M out | $2.25 | $23.12 |
| Long-context — 50M in / 5M out | $7.50 | $83.75 |
The pick
Pick GPT-6 Luna if you want the higher overall League Score; you need the bigger context window; you want the lower running cost.
All figures from the model database — sources and dates on each model page. Cost your own workload or compare a different pair.
Frequently asked questions
Which is better overall, GPT-6 Luna or Muse Spark 1.3?
GPT-6 Luna leads on overall League Score, 55 to 52 — a gap of 3 points on a composite of sourced benchmarks. That is overall form, not every category: check the per-category verdicts before choosing.
Which is cheaper, GPT-6 Luna or Muse Spark 1.3?
GPT-6 Luna is cheaper: $0.20 vs $2.00 blended per 1M tokens (3:1 input/output mix) — about 10.0x less per token.
Which has the bigger context window, GPT-6 Luna or Muse Spark 1.3?
GPT-6 Luna, with 1.1M of context against 1M for Muse Spark 1.3.
Are GPT-6 Luna and Muse Spark 1.3 open source?
GPT-6 Luna is closed weights — API access only; Muse Spark 1.3 is closed weights — API access only.