Model comparison
Claude 3 Sonnet vs GPT-5.3 Codex
GPT-5.3 Codex is the stronger model overall, scoring 45.8 to 29.0 on the Noometry Index.
Last verified . 2 shared benchmarks.
Summary
- They share 2 benchmarks with published results for both. Claude 3 Sonnet scores higher in 0 categories and GPT-5.3 Codex in 1 category; one gap is clear of the uncertainty.
- The widest gap is in coding, where GPT-5.3 Codex leads 48.6 to 29.6.
- The biggest single-benchmark swing is WeirdML: 10.2% for Claude 3 Sonnet and 79.3% for GPT-5.3 Codex.
Side by side
| Claude 3 Sonnet | GPT-5.3 Codex | |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Noometry Index | 29.0 | 45.8 |
| Released | 2024-02-29 | 2026-02-05 |
| Weights | Proprietary | Proprietary |
| Context window | — | 400K |
| Max output | — | 128K |
| Input $ / M tokens | — | $1.75 |
| Output $ / M tokens | — | $14 |
| Results tracked | 30 | 8 |
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Category by category
Coding GPT-5.3 Codex leads
Claude 3 Sonnet: 29.6 (#302), GPT-5.3 Codex: 48.6 (#56)
| Benchmark | Claude 3 Sonnet | GPT-5.3 Codex |
|---|---|---|
| WeirdML | 10.2% | 79.3% |
| SWE-bench Verified | — | 74.8% |
| LMArena WebDev | — | 1409 |
| BigCodeBench Instruct | 42.7% | — |
| LMArena Coding | 1223 | — |
| BigCodeBench Complete | 53.8% | — |
| ALE-Bench | — | 1,655 |
| HumanEval+ | 64% | — |
| MBPP+ | 69.3% | — |
Agentic & Tool Use Not comparable
Claude 3 Sonnet: —, GPT-5.3 Codex: 48.0 (#9)
| Benchmark | Claude 3 Sonnet | GPT-5.3 Codex |
|---|---|---|
| Terminal-Bench | — | 78.4% |
| METR Time Horizons | — | 74.5% |
| Vending-Bench 2 | — | 5,940 |
Reasoning Not comparable
Claude 3 Sonnet: 20.5 (#237), GPT-5.3 Codex: —
| Benchmark | Claude 3 Sonnet | GPT-5.3 Codex |
|---|---|---|
| Epoch Capabilities Index | 120.7 | 156.77 |
| LMArena Hard Prompts | 1197 | — |
| DTBench | 53.6% | — |
| WinoGrande | 75.1% | — |
Math Not comparable
Claude 3 Sonnet: 10.7 (#310), GPT-5.3 Codex: —
| Benchmark | Claude 3 Sonnet | GPT-5.3 Codex |
|---|---|---|
| OTIS Mock AIME 2024-2025 | 2.5% | — |
| LMArena Math | 1213 | — |
| MATH Level 5 | 18.2% | — |
Knowledge Not comparable
Claude 3 Sonnet: 21.1 (#276), GPT-5.3 Codex: —
| Benchmark | Claude 3 Sonnet | GPT-5.3 Codex |
|---|---|---|
| GPQA Diamond | 40.6% | — |
| LMArena Expert | 1173 | — |
| MMLU | 75.9% | — |
Multimodal Not comparable
Claude 3 Sonnet: 25.2 (#125), GPT-5.3 Codex: —
| Benchmark | Claude 3 Sonnet | GPT-5.3 Codex |
|---|---|---|
| LMArena Vision | 984 | — |
Multilingual Not comparable
Claude 3 Sonnet: 37.8 (#234), GPT-5.3 Codex: —
| Benchmark | Claude 3 Sonnet | GPT-5.3 Codex |
|---|---|---|
| LMArena Non-English | 1205 | — |
| LMArena Chinese | 1189 | — |
| LMArena French | 1229 | — |
| LMArena German | 1204 | — |
| LMArena Japanese | 1131 | — |
| LMArena Korean | 1128 | — |
| LMArena Russian | 1227 | — |
| LMArena Spanish | 1204 | — |
Instruction Following Not comparable
Claude 3 Sonnet: 62.8 (#235), GPT-5.3 Codex: —
| Benchmark | Claude 3 Sonnet | GPT-5.3 Codex |
|---|---|---|
| LMArena Instruction Following | 1199 | — |
Long Context Not comparable
Claude 3 Sonnet: 36.7 (#228), GPT-5.3 Codex: —
| Benchmark | Claude 3 Sonnet | GPT-5.3 Codex |
|---|---|---|
| LMArena Longer Query | 1211 | — |
Writing & Preference Not comparable
Claude 3 Sonnet: 42.1 (#238), GPT-5.3 Codex: —
| Benchmark | Claude 3 Sonnet | GPT-5.3 Codex |
|---|---|---|
| LMArena Text | 1218 | — |
| LMArena Creative Writing | 1186 | — |
| LMArena Multi-Turn | 1227 | — |
Frequently asked questions
Is Claude 3 Sonnet better than GPT-5.3 Codex?
GPT-5.3 Codex is the stronger model overall, scoring 45.8 to 29.0 on the Noometry Index.
Is Claude 3 Sonnet or GPT-5.3 Codex better for coding?
GPT-5.3 Codex scores higher on coding benchmarks: 48.6 versus 29.6 in the Noometry coding category.
How many benchmarks do Claude 3 Sonnet and GPT-5.3 Codex share?
2 benchmarks have published results for both models. Claude 3 Sonnet has 30 scored results on Noometry and GPT-5.3 Codex has 8.