Model comparison
GPT-5.5 Pro vs Grok 4.20 (Non-Reasoning)
GPT-5.5 Pro is the stronger model overall, scoring 64.3 to 48.5 on the Noometry Index. Grok 4.20 (Non-Reasoning) costs 43× less per token, which makes it the better buy when GPT-5.5 Pro's lead doesn't matter for your workload.
Last verified . 10 shared benchmarks.
Summary
- They share 10 benchmarks with published results for both. GPT-5.5 Pro scores higher in 3 categories and Grok 4.20 (Non-Reasoning) in 0 categories; 3 gaps are clear of the uncertainty.
- The widest gap is in math, where GPT-5.5 Pro leads 83.8 to 48.0.
- The biggest single-benchmark swing is FrontierMath Tier 4: 78% for GPT-5.5 Pro and 17.1% for Grok 4.20 (Non-Reasoning).
- Grok 4.20 (Non-Reasoning) is cheaper at $1.25 / $2.50 per million input/output tokens, against $30 / $180 for GPT-5.5 Pro.
- GPT-5.5 Pro accepts more context: 1.05M tokens versus 1M.
Side by side
| GPT-5.5 Pro | Grok 4.20 (Non-Reasoning) | |
|---|---|---|
| Provider | OpenAI | xAI |
| Noometry Index | 64.3 | 48.5 |
| Released | 2026-04-23 | 2026-02-17 |
| Weights | Proprietary | Proprietary |
| Context window | 1.05M | 1M |
| Max output | 128K | 30K |
| Input $ / M tokens | $30 | $1.25 |
| Output $ / M tokens | $180 | $2.50 |
| Results tracked | 14 | 46 |
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Category by category
Coding Not comparable
GPT-5.5 Pro: —, Grok 4.20 (Non-Reasoning): 41.8 (#104)
| Benchmark | GPT-5.5 Pro | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| LMArena WebDev | — | 1374 |
| WeirdML | — | 52.3% |
| LMArena Coding | — | 1458 |
| ALE-Bench | — | 1,150 |
Agentic & Tool Use Not comparable
GPT-5.5 Pro: —, Grok 4.20 (Non-Reasoning): 34.3 (#43)
| Benchmark | GPT-5.5 Pro | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| Terminal-Bench | — | 57.3% |
| τ²-bench Banking | — | 18% |
| LMArena Search | — | 1189 |
| Vending-Bench 2 | — | 4,663 |
Reasoning GPT-5.5 Pro leads
GPT-5.5 Pro: 73.6 (#7), Grok 4.20 (Non-Reasoning): 52.2 (#30)
| Benchmark | GPT-5.5 Pro | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| ARC-AGI-2 | 84.6% | 65.1% |
| ARC-AGI-1 | 96.5% | 89.5% |
| Chess Puzzles | 64% | 24% |
| DTBench | 96% | 90.1% |
| LMCA | 53.9% | 38.7% |
| Epoch Capabilities Index | 162.45 | 152.01 |
| SimpleBench | 76.9% | — |
| Kagi LLM Benchmark | — | 75% |
| NYT Connections (extended) | — | 85.4% |
| CritPt | 30.6% | — |
| Thematic Generalization | — | 63.8% |
| LMArena Hard Prompts | — | 1451 |
| ForecastBench | — | 61.4 |
Math GPT-5.5 Pro leads
GPT-5.5 Pro: 83.8 (#8), Grok 4.20 (Non-Reasoning): 48.0 (#54)
| Benchmark | GPT-5.5 Pro | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| FrontierMath (Tiers 1-3) | 87.7% | 44.9% |
| FrontierMath Tier 4 | 78% | 17.1% |
| OTIS Mock AIME 2024-2025 | 100% | 92.2% |
| ProofBench | — | 14% |
| LMArena Math | — | 1455 |
| FrontierMath (Feb 2025 set) | 52.4% | — |
| FrontierMath Tier 4 (v1) | 39.6% | — |
Knowledge GPT-5.5 Pro leads
GPT-5.5 Pro: 64.2 (#17), Grok 4.20 (Non-Reasoning): 52.8 (#54)
| Benchmark | GPT-5.5 Pro | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| GPQA Diamond | 93.9% | 89.3% |
| SimpleQA Verified | — | 30.2% |
| LMArena Expert | — | 1440 |
Multimodal Not comparable
GPT-5.5 Pro: —, Grok 4.20 (Non-Reasoning): 33.2 (#88)
| Benchmark | GPT-5.5 Pro | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| LMArena Vision | — | 1263 |
| Blueprint-Bench 2 | — | 0% |
| LMArena Document | — | 1416 |
Multilingual Not comparable
GPT-5.5 Pro: —, Grok 4.20 (Non-Reasoning): 54.7 (#38)
| Benchmark | GPT-5.5 Pro | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| LMArena Non-English | — | 1440 |
| LMArena Chinese | — | 1481 |
| LMArena French | — | 1477 |
| LMArena German | — | 1463 |
| LMArena Japanese | — | 1450 |
| LMArena Korean | — | 1417 |
| LMArena Russian | — | 1457 |
| LMArena Spanish | — | 1442 |
Instruction Following Not comparable
GPT-5.5 Pro: —, Grok 4.20 (Non-Reasoning): 75.0 (#79)
| Benchmark | GPT-5.5 Pro | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| LMArena Instruction Following | — | 1420 |
Long Context Not comparable
GPT-5.5 Pro: —, Grok 4.20 (Non-Reasoning): 45.4 (#33)
| Benchmark | GPT-5.5 Pro | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| CL-bench | — | 22.2% |
| CL-bench Life | — | 11.9% |
| LMArena Longer Query | — | 1436 |
Writing & Preference Not comparable
GPT-5.5 Pro: —, Grok 4.20 (Non-Reasoning): 65.9 (#42)
| Benchmark | GPT-5.5 Pro | Grok 4.20 (Non-Reasoning) |
|---|---|---|
| LMArena Text | — | 1451 |
| LMArena Creative Writing | — | 1439 |
| EQ-Bench Creative Writing | — | 1574 |
| LMArena Multi-Turn | — | 1456 |
Frequently asked questions
Is GPT-5.5 Pro better than Grok 4.20 (Non-Reasoning)?
GPT-5.5 Pro is the stronger model overall, scoring 64.3 to 48.5 on the Noometry Index. Grok 4.20 (Non-Reasoning) costs 43× less per token, which makes it the better buy when GPT-5.5 Pro's lead doesn't matter for your workload.
Which is cheaper, GPT-5.5 Pro or Grok 4.20 (Non-Reasoning)?
Grok 4.20 (Non-Reasoning) is cheaper. It lists at $1.25 per million input tokens and $2.50 per million output tokens; GPT-5.5 Pro lists at $30 and $180.
Which has the bigger context window?
GPT-5.5 Pro does, with 1.05M tokens against 1M.
How many benchmarks do GPT-5.5 Pro and Grok 4.20 (Non-Reasoning) share?
10 benchmarks have published results for both models. GPT-5.5 Pro has 14 scored results on Noometry and Grok 4.20 (Non-Reasoning) has 46.