Model comparison
Claude 2.1 vs GPT-5.3 Codex
GPT-5.3 Codex is the stronger model overall, scoring 45.8 to 25.2 on the Noometry Index.
Last verified . 2 shared benchmarks.
Summary
- They share 2 benchmarks with published results for both. Claude 2.1 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 26.2.
- The biggest single-benchmark swing is WeirdML: 7.1% for Claude 2.1 and 79.3% for GPT-5.3 Codex.
Side by side
| Claude 2.1 | GPT-5.3 Codex | |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Noometry Index | 25.2 | 45.8 |
| Released | 2023-11-21 | 2026-02-05 |
| Weights | Proprietary | Proprietary |
| Context window | — | 400K |
| Max output | — | 128K |
| Input $ / M tokens | — | $1.75 |
| Output $ / M tokens | — | $14 |
| Results tracked | 7 | 8 |
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Category by category
Coding GPT-5.3 Codex leads
Claude 2.1: 26.2 (#327), GPT-5.3 Codex: 48.6 (#56)
| Benchmark | Claude 2.1 | GPT-5.3 Codex |
|---|---|---|
| WeirdML | 7.1% | 79.3% |
| SWE-bench Verified | — | 74.8% |
| LMArena WebDev | — | 1409 |
| ALE-Bench | — | 1,655 |
Agentic & Tool Use Not comparable
Claude 2.1: —, GPT-5.3 Codex: 48.0 (#9)
| Benchmark | Claude 2.1 | GPT-5.3 Codex |
|---|---|---|
| Terminal-Bench | — | 78.4% |
| METR Time Horizons | — | 74.5% |
| Vending-Bench 2 | — | 5,940 |
Reasoning Not comparable
Claude 2.1: 21.4 (#221), GPT-5.3 Codex: —
| Benchmark | Claude 2.1 | GPT-5.3 Codex |
|---|---|---|
| Epoch Capabilities Index | 119.27 | 156.77 |
| DTBench | 51% | — |
| ForecastBench | 54.2 | — |
Math Not comparable
Claude 2.1: 10.2 (#315), GPT-5.3 Codex: —
| Benchmark | Claude 2.1 | GPT-5.3 Codex |
|---|---|---|
| OTIS Mock AIME 2024-2025 | 1.9% | — |
Knowledge Not comparable
Claude 2.1: 15.4 (#292), GPT-5.3 Codex: —
| Benchmark | Claude 2.1 | GPT-5.3 Codex |
|---|---|---|
| GPQA Diamond | 33% | — |
| MMLU | 73.5% | — |
Frequently asked questions
Is Claude 2.1 better than GPT-5.3 Codex?
GPT-5.3 Codex is the stronger model overall, scoring 45.8 to 25.2 on the Noometry Index.
Is Claude 2.1 or GPT-5.3 Codex better for coding?
GPT-5.3 Codex scores higher on coding benchmarks: 48.6 versus 26.2 in the Noometry coding category.
How many benchmarks do Claude 2.1 and GPT-5.3 Codex share?
2 benchmarks have published results for both models. Claude 2.1 has 7 scored results on Noometry and GPT-5.3 Codex has 8.