Model comparison
Claude 3.5 Sonnet vs GPT-5.3 Codex
GPT-5.3 Codex is the stronger model overall, scoring 45.8 to 34.6 on the Noometry Index.
Last verified . 3 shared benchmarks.
Summary
- They share 3 benchmarks with published results for both. Claude 3.5 Sonnet scores higher in 0 categories and GPT-5.3 Codex in 2 categories; 2 gaps are clear of the uncertainty.
- The widest gap is in agentic & tool use, where GPT-5.3 Codex leads 48.0 to 32.3.
- The biggest single-benchmark swing is WeirdML: 40% for Claude 3.5 Sonnet and 79.3% for GPT-5.3 Codex.
Side by side
| Claude 3.5 Sonnet | GPT-5.3 Codex | |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Noometry Index | 34.6 | 45.8 |
| Released | 2024-06-20 | 2026-02-05 |
| Weights | Proprietary | Proprietary |
| Context window | — | 400K |
| Max output | — | 128K |
| Input $ / M tokens | — | $1.75 |
| Output $ / M tokens | — | $14 |
| Results tracked | 60 | 8 |
Sponsored placements are available on pages like this one. Advertise on Noometry
Category by category
Coding GPT-5.3 Codex leads
Claude 3.5 Sonnet: 39.0 (#165), GPT-5.3 Codex: 48.6 (#56)
| Benchmark | Claude 3.5 Sonnet | GPT-5.3 Codex |
|---|---|---|
| WeirdML | 40% | 79.3% |
| SWE-bench Verified | — | 74.8% |
| Aider Polyglot | 51.6% | — |
| LMArena WebDev | — | 1409 |
| GSO | 4.6% | — |
| BigCodeBench Instruct | 46.8% | — |
| LiveBench Coding | 67.1% | — |
| LMArena Coding | 1342 | — |
| BigCodeBench Complete | 58.6% | — |
| CadEval | 48% | — |
| ALE-Bench | — | 1,655 |
| HumanEval+ | 81.7% | — |
| MBPP+ | 74.3% | — |
Agentic & Tool Use GPT-5.3 Codex leads
Claude 3.5 Sonnet: 32.3 (#67), GPT-5.3 Codex: 48.0 (#9)
| Benchmark | Claude 3.5 Sonnet | GPT-5.3 Codex |
|---|---|---|
| METR Time Horizons | 45.2% | 74.5% |
| Terminal-Bench | — | 78.4% |
| TheAgentCompany | 24% | — |
| Cybench | 17.5% | — |
| BALROG | 32.6% | — |
| Vending-Bench 2 | — | 5,940 |
Reasoning Not comparable
Claude 3.5 Sonnet: 23.1 (#183), GPT-5.3 Codex: —
| Benchmark | Claude 3.5 Sonnet | GPT-5.3 Codex |
|---|---|---|
| Epoch Capabilities Index | 133.55 | 156.77 |
| SimpleBench | 41.4% | — |
| EnigmaEval | 0.9% | — |
| LiveBench Reasoning | 56.7% | — |
| LMArena Hard Prompts | 1305 | — |
| DTBench | 67.8% | — |
| LiveBench Data Analysis | 55% | — |
| ForecastBench | 60.7 | — |
| LiveBench | 59% | — |
Math Not comparable
Claude 3.5 Sonnet: 19.2 (#288), GPT-5.3 Codex: —
| Benchmark | Claude 3.5 Sonnet | GPT-5.3 Codex |
|---|---|---|
| OTIS Mock AIME 2024-2025 | 8.5% | — |
| Omni-MATH | 27.6% | — |
| LiveBench Math | 52.3% | — |
| LMArena Math | 1307 | — |
| MATH Level 5 | 56.9% | — |
| FrontierMath (Feb 2025 set) | 2.1% | — |
| FrontierMath Tier 4 (v1) | 0% | — |
Knowledge Not comparable
Claude 3.5 Sonnet: 28.6 (#245), GPT-5.3 Codex: —
| Benchmark | Claude 3.5 Sonnet | GPT-5.3 Codex |
|---|---|---|
| GPQA Diamond | 55.3% | — |
| Humanity's Last Exam | 4.1% | — |
| MMLU-Pro | 77.7% | — |
| Confabulations | 19.9% | — |
| GPQA (HELM) | 56.5% | — |
| LMArena Expert | 1265 | — |
| MMLU | 87.3% | — |
Multimodal Not comparable
Claude 3.5 Sonnet: 26.5 (#120), GPT-5.3 Codex: —
| Benchmark | Claude 3.5 Sonnet | GPT-5.3 Codex |
|---|---|---|
| LMArena Vision | 1125 | — |
| Video-MME | 60% | — |
| GeoBench | 62% | — |
| VPCT | 33% | — |
Multilingual Not comparable
Claude 3.5 Sonnet: 43.2 (#185), GPT-5.3 Codex: —
| Benchmark | Claude 3.5 Sonnet | GPT-5.3 Codex |
|---|---|---|
| LMArena Non-English | 1283 | — |
| LMArena Chinese | 1272 | — |
| LMArena French | 1305 | — |
| LMArena German | 1297 | — |
| LMArena Japanese | 1234 | — |
| LMArena Korean | 1200 | — |
| LMArena Russian | 1306 | — |
| LMArena Spanish | 1290 | — |
Instruction Following Not comparable
Claude 3.5 Sonnet: 68.8 (#182), GPT-5.3 Codex: —
| Benchmark | Claude 3.5 Sonnet | GPT-5.3 Codex |
|---|---|---|
| LiveBench Instruction Following | 69.3% | — |
| IFEval | 85.5% | — |
| LMArena Instruction Following | 1297 | — |
Long Context Not comparable
Claude 3.5 Sonnet: 39.9 (#167), GPT-5.3 Codex: —
| Benchmark | Claude 3.5 Sonnet | GPT-5.3 Codex |
|---|---|---|
| LMArena Longer Query | 1311 | — |
Writing & Preference Not comparable
Claude 3.5 Sonnet: 52.9 (#164), GPT-5.3 Codex: —
| Benchmark | Claude 3.5 Sonnet | GPT-5.3 Codex |
|---|---|---|
| LMArena Text | 1298 | — |
| LMArena Creative Writing | 1292 | — |
| Short-Story Creative Writing | 80.3% | — |
| EQ-Bench Creative Writing | 1451 | — |
| WildBench | 79.2% | — |
| LMArena Multi-Turn | 1326 | — |
| LiveBench Language | 53.8% | — |
Frequently asked questions
Is Claude 3.5 Sonnet better than GPT-5.3 Codex?
GPT-5.3 Codex is the stronger model overall, scoring 45.8 to 34.6 on the Noometry Index.
Is Claude 3.5 Sonnet or GPT-5.3 Codex better for coding?
GPT-5.3 Codex scores higher on coding benchmarks: 48.6 versus 39.0 in the Noometry coding category.
How many benchmarks do Claude 3.5 Sonnet and GPT-5.3 Codex share?
3 benchmarks have published results for both models. Claude 3.5 Sonnet has 60 scored results on Noometry and GPT-5.3 Codex has 8.