Model comparison
GPT-5.5 Instant vs Muse Glimmer
GPT-5.5 Instant is the stronger model overall, scoring 42.7 to 41.7 on the Noometry Index.
Last verified . 14 shared benchmarks.
MetaSummary
- They share 14 benchmarks with published results for both. GPT-5.5 Instant scores higher in 6 categories and Muse Glimmer in 2 categories; 7 gaps are clear of the uncertainty.
- The widest gap is in math, where Muse Glimmer leads 38.8 to 26.5.
- Muse Glimmer has downloadable open weights; the other is API-only.
Side by side
| GPT-5.5 Instant | Muse Glimmer | |
|---|---|---|
| Provider | OpenAI | Meta |
| Noometry Index | 42.7 | 41.7 |
| Released | 2026-05-05 | 2026-08-10 |
| Weights | Proprietary | Open |
| Context window | — | — |
| Max output | — | — |
| Input $ / M tokens | — | — |
| Output $ / M tokens | — | — |
| Results tracked | 27 | 15 |
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Category by category
Coding GPT-5.5 Instant leads
GPT-5.5 Instant: 44.3 (#74), Muse Glimmer: 40.4 (#142)
| Benchmark | GPT-5.5 Instant | Muse Glimmer |
|---|---|---|
| SciCode | 48.6% | 44.9% |
| LMArena Coding | 1433 | 1416 |
| LMArena WebDev | — | 1355 |
Reasoning Too close to call
GPT-5.5 Instant: 24.9 (#155), Muse Glimmer: 25.7 (#144)
| Benchmark | GPT-5.5 Instant | Muse Glimmer |
|---|---|---|
| CritPt | 0% | 2.6% |
| LMArena Hard Prompts | 1426 | 1396 |
| Chess Puzzles | 12% | — |
| Epoch Capabilities Index | 142.52 | — |
Math Muse Glimmer leads
GPT-5.5 Instant: 26.5 (#259), Muse Glimmer: 38.8 (#125)
| Benchmark | GPT-5.5 Instant | Muse Glimmer |
|---|---|---|
| LMArena Math | 1420 | 1417 |
| FrontierMath (Tiers 1-3) | 26.3% | — |
| FrontierMath Tier 4 | 2.4% | — |
| OTIS Mock AIME 2024-2025 | 68.1% | — |
Knowledge GPT-5.5 Instant leads
GPT-5.5 Instant: 48.9 (#74), Muse Glimmer: 38.5 (#143)
| Benchmark | GPT-5.5 Instant | Muse Glimmer |
|---|---|---|
| LMArena Expert | 1409 | 1386 |
| GPQA Diamond | 82.5% | — |
Multimodal Not comparable
GPT-5.5 Instant: 40.0 (#52), Muse Glimmer: —
| Benchmark | GPT-5.5 Instant | Muse Glimmer |
|---|---|---|
| LMArena Vision | 1250 | — |
| LMArena Document | 1403 | — |
Multilingual GPT-5.5 Instant leads
GPT-5.5 Instant: 52.8 (#80), Muse Glimmer: 50.5 (#122)
| Benchmark | GPT-5.5 Instant | Muse Glimmer |
|---|---|---|
| LMArena Non-English | 1417 | 1384 |
| LMArena Chinese | 1456 | 1412 |
| LMArena Russian | 1431 | 1390 |
| LMArena French | 1428 | — |
| LMArena German | 1411 | — |
| LMArena Japanese | 1408 | — |
| LMArena Korean | 1392 | — |
| LMArena Spanish | 1429 | — |
Instruction Following GPT-5.5 Instant leads
GPT-5.5 Instant: 74.2 (#100), Muse Glimmer: 72.6 (#135)
| Benchmark | GPT-5.5 Instant | Muse Glimmer |
|---|---|---|
| LMArena Instruction Following | 1406 | 1375 |
Long Context GPT-5.5 Instant leads
GPT-5.5 Instant: 43.4 (#96), Muse Glimmer: 42.1 (#129)
| Benchmark | GPT-5.5 Instant | Muse Glimmer |
|---|---|---|
| LMArena Longer Query | 1422 | 1382 |
Writing & Preference GPT-5.5 Instant leads
GPT-5.5 Instant: 61.8 (#85), Muse Glimmer: 57.5 (#126)
| Benchmark | GPT-5.5 Instant | Muse Glimmer |
|---|---|---|
| LMArena Text | 1419 | 1389 |
| LMArena Creative Writing | 1419 | 1339 |
| LMArena Multi-Turn | 1433 | 1399 |
Frequently asked questions
Is GPT-5.5 Instant better than Muse Glimmer?
GPT-5.5 Instant is the stronger model overall, scoring 42.7 to 41.7 on the Noometry Index.
Is GPT-5.5 Instant or Muse Glimmer better for coding?
GPT-5.5 Instant scores higher on coding benchmarks: 44.3 versus 40.4 in the Noometry coding category.
How many benchmarks do GPT-5.5 Instant and Muse Glimmer share?
14 benchmarks have published results for both models. GPT-5.5 Instant has 27 scored results on Noometry and Muse Glimmer has 15.