Model comparison
GPT-5.6 Terra vs Grok 4 Fast
GPT-5.6 Terra is the stronger model overall, scoring 59.1 to 39.0 on the Noometry Index.
Last verified . 24 shared benchmarks.
Summary
- They share 24 benchmarks with published results for both. GPT-5.6 Terra scores higher in 8 categories and Grok 4 Fast in 1 category; 9 gaps are clear of the uncertainty.
- The widest gap is in math, where GPT-5.6 Terra leads 81.5 to 36.1.
- The biggest single-benchmark swing is ARC-AGI-2: 83.9% for GPT-5.6 Terra and 5.3% for Grok 4 Fast.
Side by side
| GPT-5.6 Terra | Grok 4 Fast | |
|---|---|---|
| Provider | OpenAI | xAI |
| Noometry Index | 59.1 | 39.0 |
| Released | 2026-07-09 | 2025-09-19 |
| Weights | Proprietary | Proprietary |
| Context window | 1.05M | — |
| Max output | 128K | — |
| Input $ / M tokens | $2 | — |
| Output $ / M tokens | $12 | — |
| Results tracked | 52 | 30 |
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Category by category
Coding GPT-5.6 Terra leads
GPT-5.6 Terra: 57.1 (#16), Grok 4 Fast: 32.3 (#264)
| Benchmark | GPT-5.6 Terra | Grok 4 Fast |
|---|---|---|
| LMArena WebDev | 1520 | 1160 |
| WeirdML | 78.3% | 42.9% |
| LMArena Coding | 1484 | 1429 |
| DeepSWE | 69.6% | — |
| FrontierCode | 41.3% | — |
| CursorBench | 41.3% | — |
| SciCode | 55% | — |
| ALE-Bench | 1,951 | — |
Agentic & Tool Use GPT-5.6 Terra leads
GPT-5.6 Terra: 40.2 (#23), Grok 4 Fast: 29.3 (#80)
| Benchmark | GPT-5.6 Terra | Grok 4 Fast |
|---|---|---|
| APEX-Agents | 58.2% | — |
| τ²-bench Banking | — | 15.7% |
| Cybench | — | 30% |
| BALROG | 53.2% | — |
| GDP.pdf | 24.7% | — |
| LMArena Search | — | 1171 |
| Vending-Bench 2 | 7,343 | — |
Reasoning GPT-5.6 Terra leads
GPT-5.6 Terra: 60.6 (#19), Grok 4 Fast: 22.5 (#179)
| Benchmark | GPT-5.6 Terra | Grok 4 Fast |
|---|---|---|
| ARC-AGI-2 | 83.9% | 5.3% |
| Kagi LLM Benchmark | 51.3% | 66.1% |
| ARC-AGI-1 | 96.5% | 48.5% |
| LMArena Hard Prompts | 1467 | 1413 |
| DTBench | 93.3% | 82.7% |
| Epoch Capabilities Index | 159.31 | 144.21 |
| SimpleBench | 48.9% | — |
| NYT Connections (extended) | 78.4% | — |
| CritPt | 30% | — |
| Chess Puzzles | 54% | — |
| Mystery Game Puzzles | 35% | — |
| LMCA | 55% | — |
| Surface Evolver Bench | 83.8% | — |
| ForecastBench | — | 60.5 |
Math GPT-5.6 Terra leads
GPT-5.6 Terra: 81.5 (#10), Grok 4 Fast: 36.1 (#126)
| Benchmark | GPT-5.6 Terra | Grok 4 Fast |
|---|---|---|
| LMArena Math | 1463 | 1419 |
| FrontierMath (Tiers 1-3) | 86% | — |
| FrontierMath Tier 4 | 70.7% | — |
| OTIS Mock AIME 2024-2025 | 99.7% | — |
| ProofBench | 74% | — |
Knowledge GPT-5.6 Terra leads
GPT-5.6 Terra: 61.3 (#27), Grok 4 Fast: 31.5 (#211)
| Benchmark | GPT-5.6 Terra | Grok 4 Fast |
|---|---|---|
| LMArena Expert | 1492 | 1411 |
| GPQA Diamond | 93.3% | — |
| SimpleQA Verified | 43.2% | — |
| Vectara Hallucination Rate | — | 19.7% |
Multimodal Not comparable
GPT-5.6 Terra: 47.5 (#10), Grok 4 Fast: —
| Benchmark | GPT-5.6 Terra | Grok 4 Fast |
|---|---|---|
| LMArena Vision | 1271 | — |
| Blueprint-Bench 2 | 30.8% | — |
| Furniture Assembly | 54.2% | — |
| LMArena Document | 1472 | — |
Multilingual GPT-5.6 Terra leads
GPT-5.6 Terra: 54.5 (#42), Grok 4 Fast: 51.5 (#106)
| Benchmark | GPT-5.6 Terra | Grok 4 Fast |
|---|---|---|
| LMArena Non-English | 1439 | 1397 |
| LMArena Chinese | 1514 | 1458 |
| LMArena French | 1476 | 1433 |
| LMArena German | 1462 | 1383 |
| LMArena Japanese | 1446 | 1358 |
| LMArena Korean | 1420 | 1359 |
| LMArena Russian | 1450 | 1387 |
| LMArena Spanish | 1455 | 1414 |
Instruction Following GPT-5.6 Terra leads
GPT-5.6 Terra: 76.6 (#38), Grok 4 Fast: 73.4 (#116)
| Benchmark | GPT-5.6 Terra | Grok 4 Fast |
|---|---|---|
| LMArena Instruction Following | 1453 | 1388 |
Long Context Grok 4 Fast leads
GPT-5.6 Terra: 44.4 (#64), Grok 4 Fast: 63.2 (#3)
| Benchmark | GPT-5.6 Terra | Grok 4 Fast |
|---|---|---|
| LMArena Longer Query | 1452 | 1415 |
| Fiction.LiveBench | — | 94.4% |
Writing & Preference GPT-5.6 Terra leads
GPT-5.6 Terra: 70.4 (#21), Grok 4 Fast: 60.2 (#96)
| Benchmark | GPT-5.6 Terra | Grok 4 Fast |
|---|---|---|
| LMArena Text | 1446 | 1407 |
| LMArena Creative Writing | 1411 | 1388 |
| LMArena Multi-Turn | 1451 | 1414 |
| EQ-Bench Creative Writing | 1855 | — |
| EQ-Bench 4 | 1234 | — |
Frequently asked questions
Is GPT-5.6 Terra better than Grok 4 Fast?
GPT-5.6 Terra is the stronger model overall, scoring 59.1 to 39.0 on the Noometry Index.
Is GPT-5.6 Terra or Grok 4 Fast better for coding?
GPT-5.6 Terra scores higher on coding benchmarks: 57.1 versus 32.3 in the Noometry coding category.
How many benchmarks do GPT-5.6 Terra and Grok 4 Fast share?
24 benchmarks have published results for both models. GPT-5.6 Terra has 52 scored results on Noometry and Grok 4 Fast has 30.