Model comparison
Claude Opus 5.5 vs Grok 4.3
Claude Opus 5.5 is the stronger model overall, scoring 68.5 to 43.6 on the Noometry Index. Grok 4.3 costs 5.1× less per token, which makes it the better buy when Claude Opus 5.5's lead doesn't matter for your workload.
Last verified . 24 shared benchmarks.
Summary
- They share 24 benchmarks with published results for both. Claude Opus 5.5 scores higher in 10 categories and Grok 4.3 in 0 categories; 10 gaps are clear of the uncertainty.
- The widest gap is in math, where Claude Opus 5.5 leads 92.4 to 45.8.
- The biggest single-benchmark swing is ProofBench: 100% for Claude Opus 5.5 and 11% for Grok 4.3.
- Grok 4.3 is cheaper at $1.25 / $2.50 per million input/output tokens, against $4 / $20 for Claude Opus 5.5.
Side by side
| Claude Opus 5.5 | Grok 4.3 | |
|---|---|---|
| Provider | Anthropic | xAI |
| Noometry Index | 68.5 | 43.6 |
| Released | 2026-09-22 | 2026-04-17 |
| Weights | Proprietary | Proprietary |
| Context window | 1M | 1M |
| Max output | 128K | 30K |
| Input $ / M tokens | $4 | $1.25 |
| Output $ / M tokens | $20 | $2.50 |
| Results tracked | 35 | 40 |
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Category by category
Coding Claude Opus 5.5 leads
Claude Opus 5.5: 71.4 (#1), Grok 4.3: 41.3 (#117)
| Benchmark | Claude Opus 5.5 | Grok 4.3 |
|---|---|---|
| LMArena WebDev | 1820 | 1357 |
| SciCode | 66.9% | 47.3% |
| LMArena Coding | 1545 | 1415 |
| FrontierCode | 54.4% | — |
| CursorBench | 57.8% | — |
| FrontierSWE | 62.3% | — |
| WeirdML | — | 49.9% |
| MirrorCode | 77.4% | — |
| ALE-Bench | — | 944.17 |
Agentic & Tool Use Claude Opus 5.5 leads
Claude Opus 5.5: 45.3 (#13), Grok 4.3: 27.6 (#93)
| Benchmark | Claude Opus 5.5 | Grok 4.3 |
|---|---|---|
| GDP.pdf | 30.6% | 8% |
| APEX-Agents | 73.5% | — |
| LMArena Search | — | 1165 |
| Vending-Bench 2 | — | 35.26 |
Reasoning Claude Opus 5.5 leads
Claude Opus 5.5: 79.5 (#2), Grok 4.3: 34.9 (#60)
| Benchmark | Claude Opus 5.5 | Grok 4.3 |
|---|---|---|
| NYT Connections (extended) | 88.5% | 55.2% |
| CritPt | 31.7% | 8% |
| LMArena Hard Prompts | 1545 | 1397 |
| DTBench | 98.9% | 90.7% |
| LMCA | 68.2% | 38.3% |
| ARC-AGI-2 | 92.5% | — |
| ARC-AGI-1 | 97.5% | — |
| Chess Puzzles | — | 25% |
| EBR-Bench | 71.4% | — |
| Mystery Game Puzzles | 71% | — |
| Epoch Capabilities Index | — | 149.13 |
| ForecastBench | — | 60.3 |
Math Claude Opus 5.5 leads
Claude Opus 5.5: 92.4 (#2), Grok 4.3: 45.8 (#60)
| Benchmark | Claude Opus 5.5 | Grok 4.3 |
|---|---|---|
| FrontierMath (Tiers 1-3) | 91.2% | 42.8% |
| FrontierMath Tier 4 | 95% | 14.6% |
| OTIS Mock AIME 2024-2025 | 100% | 93.3% |
| ProofBench | 100% | 11% |
| LMArena Math | — | 1388 |
Knowledge Claude Opus 5.5 leads
Claude Opus 5.5: 66.6 (#9), Grok 4.3: 52.5 (#57)
| Benchmark | Claude Opus 5.5 | Grok 4.3 |
|---|---|---|
| GPQA Diamond | 90.6% | 88.8% |
| SimpleQA Verified | 72.2% | 33.2% |
| LMArena Expert | 1564 | 1385 |
Multimodal Claude Opus 5.5 leads
Claude Opus 5.5: 56.5 (#2), Grok 4.3: 31.6 (#96)
| Benchmark | Claude Opus 5.5 | Grok 4.3 |
|---|---|---|
| LMArena Vision | — | 1231 |
| Blueprint-Bench 2 | — | 0% |
| Furniture Assembly | 83.3% | — |
Multilingual Claude Opus 5.5 leads
Claude Opus 5.5: 59.8 (#1), Grok 4.3: 50.7 (#114)
| Benchmark | Claude Opus 5.5 | Grok 4.3 |
|---|---|---|
| LMArena Non-English | 1513 | 1385 |
| LMArena Chinese | 1572 | 1423 |
| LMArena Russian | 1532 | 1399 |
| LMArena French | — | 1412 |
| LMArena German | — | 1395 |
| LMArena Japanese | — | 1379 |
| LMArena Korean | — | 1357 |
| LMArena Spanish | — | 1402 |
Instruction Following Claude Opus 5.5 leads
Claude Opus 5.5: 80.1 (#2), Grok 4.3: 72.3 (#135)
| Benchmark | Claude Opus 5.5 | Grok 4.3 |
|---|---|---|
| LMArena Instruction Following | 1535 | 1366 |
Long Context Claude Opus 5.5 leads
Claude Opus 5.5: 47.3 (#18), Grok 4.3: 42.5 (#118)
| Benchmark | Claude Opus 5.5 | Grok 4.3 |
|---|---|---|
| LMArena Longer Query | 1540 | 1393 |
Writing & Preference Claude Opus 5.5 leads
Claude Opus 5.5: 78.7 (#3), Grok 4.3: 58.6 (#112)
| Benchmark | Claude Opus 5.5 | Grok 4.3 |
|---|---|---|
| LMArena Text | 1518 | 1397 |
| LMArena Creative Writing | 1538 | 1380 |
| LMArena Multi-Turn | 1520 | 1406 |
| EQ-Bench Creative Writing | 2050 | — |
| EQ-Bench 4 | — | 1075 |
Frequently asked questions
Is Claude Opus 5.5 better than Grok 4.3?
Claude Opus 5.5 is the stronger model overall, scoring 68.5 to 43.6 on the Noometry Index. Grok 4.3 costs 5.1× less per token, which makes it the better buy when Claude Opus 5.5's lead doesn't matter for your workload.
Which is cheaper, Claude Opus 5.5 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; Claude Opus 5.5 lists at $4 and $20.
Is Claude Opus 5.5 or Grok 4.3 better for coding?
Claude Opus 5.5 scores higher on coding benchmarks: 71.4 versus 41.3 in the Noometry coding category.
Which has the bigger context window?
Both accept 1M tokens.
How many benchmarks do Claude Opus 5.5 and Grok 4.3 share?
24 benchmarks have published results for both models. Claude Opus 5.5 has 35 scored results on Noometry and Grok 4.3 has 40.