Model comparison
GPT-5.5 Instant vs Grok 4.20 (Non-Reasoning)
Grok 4.20 (Non-Reasoning) is the stronger model overall, scoring 48.5 to 42.5 on the Noometry Index.
Last verified . 25 shared benchmarks.
Summary
- They share 25 benchmarks with published results for both. GPT-5.5 Instant scores higher in 2 categories and Grok 4.20 (Non-Reasoning) in 7 categories; 8 gaps are clear of the uncertainty.
- The widest gap is in reasoning, where Grok 4.20 (Non-Reasoning) leads 52.2 to 24.2.
- The biggest single-benchmark swing is OTIS Mock AIME 2024-2025: 68.1% for GPT-5.5 Instant and 92.2% for Grok 4.20 (Non-Reasoning).
Side by side
| GPT-5.5 Instant | Grok 4.20 (Non-Reasoning) | |
|---|---|---|
| Provider | OpenAI | xAI |
| Noometry Index | 42.5 | 48.5 |
| Released | 2026-05-05 | 2026-02-17 |
| Weights | Proprietary | Proprietary |
| Context window | — | 1M |
| Max output | — | 30K |
| Input $ / M tokens | — | $1.25 |
| Output $ / M tokens | — | $2.50 |
| Results tracked | 27 | 46 |
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Category by category
Coding GPT-5.5 Instant leads
GPT-5.5 Instant: 43.7 (#73), Grok 4.20 (Non-Reasoning): 41.8 (#104)
| Benchmark | GPT-5.5 Instant | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| LMArena Coding | 1433 | 1458 |
| LMArena WebDev | — | 1374 |
| SciCode | 48.6% | — |
| WeirdML | — | 52.3% |
| ALE-Bench | — | 1,150 |
Agentic & Tool Use Not comparable
GPT-5.5 Instant: —, Grok 4.20 (Non-Reasoning): 34.3 (#43)
| Benchmark | GPT-5.5 Instant | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| Terminal-Bench | — | 57.3% |
| τ²-bench Banking | — | 18% |
| LMArena Search | — | 1189 |
| Vending-Bench 2 | — | 4,663 |
Reasoning Grok 4.20 (Non-Reasoning) leads
GPT-5.5 Instant: 24.2 (#149), Grok 4.20 (Non-Reasoning): 52.2 (#30)
| Benchmark | GPT-5.5 Instant | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| Chess Puzzles | 12% | 24% |
| LMArena Hard Prompts | 1426 | 1451 |
| Epoch Capabilities Index | 142.48 | 152.01 |
| ARC-AGI-2 | — | 65.1% |
| Kagi LLM Benchmark | — | 75% |
| NYT Connections (extended) | — | 85.4% |
| ARC-AGI-1 | — | 89.5% |
| CritPt | 0% | — |
| Thematic Generalization | — | 63.8% |
| DTBench | — | 90.1% |
| LMCA | — | 38.7% |
| ForecastBench | — | 61.4 |
Math Grok 4.20 (Non-Reasoning) leads
GPT-5.5 Instant: 26.1 (#241), Grok 4.20 (Non-Reasoning): 48.0 (#54)
| Benchmark | GPT-5.5 Instant | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| FrontierMath (Tiers 1-3) | 26.3% | 44.9% |
| FrontierMath Tier 4 | 2.4% | 17.1% |
| OTIS Mock AIME 2024-2025 | 68.1% | 92.2% |
| LMArena Math | 1420 | 1455 |
| ProofBench | — | 14% |
Knowledge Grok 4.20 (Non-Reasoning) leads
GPT-5.5 Instant: 48.9 (#68), Grok 4.20 (Non-Reasoning): 52.8 (#54)
| Benchmark | GPT-5.5 Instant | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| GPQA Diamond | 82.5% | 89.3% |
| LMArena Expert | 1409 | 1440 |
| SimpleQA Verified | — | 30.2% |
Multimodal GPT-5.5 Instant leads
GPT-5.5 Instant: 39.3 (#48), Grok 4.20 (Non-Reasoning): 33.2 (#88)
| Benchmark | GPT-5.5 Instant | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| LMArena Vision | 1250 | 1263 |
| LMArena Document | 1403 | 1416 |
| Blueprint-Bench 2 | — | 0% |
Multilingual Grok 4.20 (Non-Reasoning) leads
GPT-5.5 Instant: 53.0 (#76), Grok 4.20 (Non-Reasoning): 54.7 (#38)
| Benchmark | GPT-5.5 Instant | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| LMArena Non-English | 1417 | 1440 |
| LMArena Chinese | 1457 | 1481 |
| LMArena French | 1428 | 1477 |
| LMArena German | 1410 | 1463 |
| LMArena Japanese | 1408 | 1450 |
| LMArena Korean | 1393 | 1417 |
| LMArena Russian | 1430 | 1457 |
| LMArena Spanish | 1430 | 1442 |
Instruction Following Too close to call
GPT-5.5 Instant: 74.4 (#94), Grok 4.20 (Non-Reasoning): 75.0 (#79)
| Benchmark | GPT-5.5 Instant | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| LMArena Instruction Following | 1407 | 1420 |
Long Context Grok 4.20 (Non-Reasoning) leads
GPT-5.5 Instant: 43.4 (#92), Grok 4.20 (Non-Reasoning): 45.4 (#33)
| Benchmark | GPT-5.5 Instant | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| LMArena Longer Query | 1422 | 1436 |
| CL-bench | — | 22.2% |
| CL-bench Life | — | 11.9% |
Writing & Preference Grok 4.20 (Non-Reasoning) leads
GPT-5.5 Instant: 62.0 (#81), Grok 4.20 (Non-Reasoning): 65.9 (#42)
| Benchmark | GPT-5.5 Instant | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| LMArena Text | 1419 | 1451 |
| LMArena Creative Writing | 1420 | 1439 |
| LMArena Multi-Turn | 1434 | 1456 |
| EQ-Bench Creative Writing | — | 1574 |
Frequently asked questions
Is GPT-5.5 Instant better than Grok 4.20 (Non-Reasoning)?
Grok 4.20 (Non-Reasoning) is the stronger model overall, scoring 48.5 to 42.5 on the Noometry Index.
Is GPT-5.5 Instant or Grok 4.20 (Non-Reasoning) better for coding?
GPT-5.5 Instant scores higher on coding benchmarks: 43.7 versus 41.8 in the Noometry coding category.
How many benchmarks do GPT-5.5 Instant and Grok 4.20 (Non-Reasoning) share?
25 benchmarks have published results for both models. GPT-5.5 Instant has 27 scored results on Noometry and Grok 4.20 (Non-Reasoning) has 46.