Model comparison
GPT-5.5 Pro vs Grok 4.3
GPT-5.5 Pro is the stronger model overall, scoring 64.3 to 43.8 on the Noometry Index. Grok 4.3 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 . 9 shared benchmarks.
Summary
- They share 9 benchmarks with published results for both. GPT-5.5 Pro scores higher in 3 categories and Grok 4.3 in 0 categories; 3 gaps are clear of the uncertainty.
- The widest gap is in math, where GPT-5.5 Pro leads 84.0 to 46.0.
- The biggest single-benchmark swing is FrontierMath Tier 4: 78% for GPT-5.5 Pro and 14.6% for Grok 4.3.
- Grok 4.3 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 4.3 | |
|---|---|---|
| Provider | OpenAI | xAI |
| Noometry Index | 64.3 | 43.8 |
| Released | 2026-04-23 | 2026-04-17 |
| 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 | 40 |
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Category by category
Coding Not comparable
GPT-5.5 Pro: —, Grok 4.3: 41.6 (#121)
| Benchmark | GPT-5.5 Pro | Grok 4.3 |
|---|---|---|
| LMArena WebDev | — | 1357 |
| SciCode | — | 47.3% |
| WeirdML | — | 49.9% |
| LMArena Coding | — | 1415 |
| ALE-Bench | — | 944.17 |
Agentic & Tool Use Not comparable
GPT-5.5 Pro: —, Grok 4.3: 27.7 (#99)
| Benchmark | GPT-5.5 Pro | Grok 4.3 |
|---|---|---|
| GDP.pdf | — | 8% |
| LMArena Search | — | 1165 |
| Vending-Bench 2 | — | 35.26 |
Reasoning GPT-5.5 Pro leads
GPT-5.5 Pro: 73.3 (#10), Grok 4.3: 35.9 (#68)
| Benchmark | GPT-5.5 Pro | Grok 4.3 |
|---|---|---|
| CritPt | 30.6% | 8% |
| Chess Puzzles | 64% | 25% |
| DTBench | 96% | 90.7% |
| LMCA | 53.9% | 38.3% |
| Epoch Capabilities Index | 162.07 | 149.16 |
| ARC-AGI-2 | 84.6% | — |
| SimpleBench | 76.9% | — |
| NYT Connections (extended) | — | 55.2% |
| ARC-AGI-1 | 96.5% | — |
| LMArena Hard Prompts | — | 1396 |
| ForecastBench | — | 60.3 |
Math GPT-5.5 Pro leads
GPT-5.5 Pro: 84.0 (#10), Grok 4.3: 46.0 (#74)
| Benchmark | GPT-5.5 Pro | Grok 4.3 |
|---|---|---|
| FrontierMath (Tiers 1-3) | 87.7% | 42.8% |
| FrontierMath Tier 4 | 78% | 14.6% |
| OTIS Mock AIME 2024-2025 | 100% | 93.3% |
| ProofBench | — | 11% |
| LMArena Math | — | 1388 |
| FrontierMath (Feb 2025 set) | 52.4% | — |
| FrontierMath Tier 4 (v1) | 39.6% | — |
Knowledge GPT-5.5 Pro leads
GPT-5.5 Pro: 64.1 (#19), Grok 4.3: 52.5 (#62)
| Benchmark | GPT-5.5 Pro | Grok 4.3 |
|---|---|---|
| GPQA Diamond | 93.9% | 88.8% |
| SimpleQA Verified | — | 33.2% |
| LMArena Expert | — | 1385 |
Multimodal Not comparable
GPT-5.5 Pro: —, Grok 4.3: 31.6 (#104)
| Benchmark | GPT-5.5 Pro | Grok 4.3 |
|---|---|---|
| LMArena Vision | — | 1229 |
| Blueprint-Bench 2 | — | 0% |
Multilingual Not comparable
GPT-5.5 Pro: —, Grok 4.3: 50.5 (#120)
| Benchmark | GPT-5.5 Pro | Grok 4.3 |
|---|---|---|
| LMArena Non-English | — | 1385 |
| LMArena Chinese | — | 1422 |
| LMArena French | — | 1412 |
| LMArena German | — | 1395 |
| LMArena Japanese | — | 1379 |
| LMArena Korean | — | 1356 |
| LMArena Russian | — | 1399 |
| LMArena Spanish | — | 1398 |
Instruction Following Not comparable
GPT-5.5 Pro: —, Grok 4.3: 72.1 (#140)
| Benchmark | GPT-5.5 Pro | Grok 4.3 |
|---|---|---|
| LMArena Instruction Following | — | 1366 |
Long Context Not comparable
GPT-5.5 Pro: —, Grok 4.3: 42.5 (#123)
| Benchmark | GPT-5.5 Pro | Grok 4.3 |
|---|---|---|
| LMArena Longer Query | — | 1393 |
Writing & Preference Not comparable
GPT-5.5 Pro: —, Grok 4.3: 58.5 (#118)
| Benchmark | GPT-5.5 Pro | Grok 4.3 |
|---|---|---|
| LMArena Text | — | 1397 |
| LMArena Creative Writing | — | 1380 |
| EQ-Bench 4 | — | 1075 |
| LMArena Multi-Turn | — | 1406 |
Frequently asked questions
Is GPT-5.5 Pro better than Grok 4.3?
GPT-5.5 Pro is the stronger model overall, scoring 64.3 to 43.8 on the Noometry Index. Grok 4.3 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 4.3?
Grok 4.3 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 4.3 share?
9 benchmarks have published results for both models. GPT-5.5 Pro has 14 scored results on Noometry and Grok 4.3 has 40.