Model comparison
Claude Opus 5.5 vs GPT-5.3 Chat
Claude Opus 5.5 is the stronger model overall, scoring 68.5 to 42.1 on the Noometry Index. GPT-5.3 Chat costs 1.7× less per token, which makes it the better buy when Claude Opus 5.5's lead doesn't matter for your workload.
Last verified . 12 shared benchmarks.
Summary
- They share 12 benchmarks with published results for both. Claude Opus 5.5 scores higher in 8 categories and GPT-5.3 Chat in 0 categories; 8 gaps are clear of the uncertainty.
- The widest gap is in math, where Claude Opus 5.5 leads 92.4 to 35.4.
- GPT-5.3 Chat is cheaper at $1.75 / $14 per million input/output tokens, against $4 / $20 for Claude Opus 5.5.
- Claude Opus 5.5 accepts more context: 1M tokens versus 128K.
Side by side
| Claude Opus 5.5 | GPT-5.3 Chat | |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Noometry Index | 68.5 | 42.1 |
| Released | 2026-09-22 | 2026-03-03 |
| Weights | Proprietary | Proprietary |
| Context window | 1M | 128K |
| Max output | 128K | 16K |
| Input $ / M tokens | $4 | $1.75 |
| Output $ / M tokens | $20 | $14 |
| Results tracked | 35 | 18 |
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Category by category
Coding Claude Opus 5.5 leads
Claude Opus 5.5: 71.4 (#1), GPT-5.3 Chat: 40.8 (#124)
| Benchmark | Claude Opus 5.5 | GPT-5.3 Chat |
|---|---|---|
| LMArena Coding | 1545 | 1408 |
| FrontierCode | 54.4% | — |
| CursorBench | 57.8% | — |
| LMArena WebDev | 1820 | — |
| FrontierSWE | 62.3% | — |
| SciCode | 66.9% | — |
| MirrorCode | 77.4% | — |
Agentic & Tool Use Not comparable
Claude Opus 5.5: 45.3 (#13), GPT-5.3 Chat: —
| Benchmark | Claude Opus 5.5 | GPT-5.3 Chat |
|---|---|---|
| APEX-Agents | 73.5% | — |
| GDP.pdf | 30.6% | — |
Reasoning Claude Opus 5.5 leads
Claude Opus 5.5: 79.5 (#2), GPT-5.3 Chat: 27.3 (#105)
| Benchmark | Claude Opus 5.5 | GPT-5.3 Chat |
|---|---|---|
| LMArena Hard Prompts | 1545 | 1399 |
| ARC-AGI-2 | 92.5% | — |
| NYT Connections (extended) | 88.5% | — |
| ARC-AGI-1 | 97.5% | — |
| CritPt | 31.7% | — |
| EBR-Bench | 71.4% | — |
| Mystery Game Puzzles | 71% | — |
| DTBench | 98.9% | — |
| LMCA | 68.2% | — |
Math Claude Opus 5.5 leads
Claude Opus 5.5: 92.4 (#2), GPT-5.3 Chat: 35.4 (#146)
| Benchmark | Claude Opus 5.5 | GPT-5.3 Chat |
|---|---|---|
| FrontierMath (Tiers 1-3) | 91.2% | — |
| FrontierMath Tier 4 | 95% | — |
| OTIS Mock AIME 2024-2025 | 100% | — |
| ProofBench | 100% | — |
| LMArena Math | — | 1389 |
Knowledge Claude Opus 5.5 leads
Claude Opus 5.5: 66.6 (#9), GPT-5.3 Chat: 38.2 (#137)
| Benchmark | Claude Opus 5.5 | GPT-5.3 Chat |
|---|---|---|
| LMArena Expert | 1564 | 1397 |
| GPQA Diamond | 90.6% | — |
| SimpleQA Verified | 72.2% | — |
Multimodal Not comparable
Claude Opus 5.5: 56.5 (#2), GPT-5.3 Chat: —
| Benchmark | Claude Opus 5.5 | GPT-5.3 Chat |
|---|---|---|
| Furniture Assembly | 83.3% | — |
Multilingual Claude Opus 5.5 leads
Claude Opus 5.5: 59.8 (#1), GPT-5.3 Chat: 50.5 (#119)
| Benchmark | Claude Opus 5.5 | GPT-5.3 Chat |
|---|---|---|
| LMArena Non-English | 1513 | 1383 |
| LMArena Chinese | 1572 | 1433 |
| LMArena Russian | 1532 | 1400 |
| LMArena French | — | 1398 |
| LMArena German | — | 1384 |
| LMArena Japanese | — | 1351 |
| LMArena Korean | — | 1347 |
| LMArena Spanish | — | 1371 |
Instruction Following Claude Opus 5.5 leads
Claude Opus 5.5: 80.1 (#2), GPT-5.3 Chat: 73.0 (#124)
| Benchmark | Claude Opus 5.5 | GPT-5.3 Chat |
|---|---|---|
| LMArena Instruction Following | 1535 | 1378 |
Long Context Claude Opus 5.5 leads
Claude Opus 5.5: 47.3 (#18), GPT-5.3 Chat: 42.6 (#115)
| Benchmark | Claude Opus 5.5 | GPT-5.3 Chat |
|---|---|---|
| LMArena Longer Query | 1540 | 1396 |
Writing & Preference Claude Opus 5.5 leads
Claude Opus 5.5: 78.7 (#3), GPT-5.3 Chat: 63.3 (#65)
| Benchmark | Claude Opus 5.5 | GPT-5.3 Chat |
|---|---|---|
| LMArena Text | 1518 | 1389 |
| LMArena Creative Writing | 1538 | 1356 |
| EQ-Bench Creative Writing | 2050 | 1690 |
| LMArena Multi-Turn | 1520 | 1413 |
Frequently asked questions
Is Claude Opus 5.5 better than GPT-5.3 Chat?
Claude Opus 5.5 is the stronger model overall, scoring 68.5 to 42.1 on the Noometry Index. GPT-5.3 Chat costs 1.7× 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 GPT-5.3 Chat?
GPT-5.3 Chat is cheaper. It lists at $1.75 per million input tokens and $14 per million output tokens; Claude Opus 5.5 lists at $4 and $20.
Is Claude Opus 5.5 or GPT-5.3 Chat better for coding?
Claude Opus 5.5 scores higher on coding benchmarks: 71.4 versus 40.8 in the Noometry coding category.
Which has the bigger context window?
Claude Opus 5.5 does, with 1M tokens against 128K.
How many benchmarks do Claude Opus 5.5 and GPT-5.3 Chat share?
12 benchmarks have published results for both models. Claude Opus 5.5 has 35 scored results on Noometry and GPT-5.3 Chat has 18.