Model comparison
GPT-5.3 Codex vs GPT-5-Codex
GPT-5.3 Codex is the stronger model overall, scoring 45.8 to 37.9 on the Noometry Index.
Last verified . 2 shared benchmarks.
Summary
- They share 2 benchmarks with published results for both. GPT-5.3 Codex scores higher in 2 categories and GPT-5-Codex in 0 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 31.0.
- The biggest single-benchmark swing is Terminal-Bench: 78.4% for GPT-5.3 Codex and 44.3% for GPT-5-Codex.
- GPT-5-Codex is cheaper at $1.25 / $10 per million input/output tokens, against $1.75 / $14 for GPT-5.3 Codex.
Side by side
| GPT-5.3 Codex | GPT-5-Codex | |
|---|---|---|
| Provider | OpenAI | OpenAI |
| Noometry Index | 45.8 | 37.9 |
| Released | 2026-02-05 | 2025-09-15 |
| Weights | Proprietary | Proprietary |
| Context window | 400K | 400K |
| Max output | 128K | 128K |
| Input $ / M tokens | $1.75 | $1.25 |
| Output $ / M tokens | $14 | $10 |
| Results tracked | 8 | 3 |
Sponsored placements are available on pages like this one. Advertise on Noometry
Category by category
Coding GPT-5.3 Codex leads
GPT-5.3 Codex: 48.6 (#56), GPT-5-Codex: 42.4 (#103)
| Benchmark | GPT-5.3 Codex | GPT-5-Codex |
|---|---|---|
| WeirdML | 79.3% | 54.5% |
| SWE-bench Verified | 74.8% | — |
| LMArena WebDev | 1409 | — |
| ALE-Bench | 1,655 | — |
Agentic & Tool Use GPT-5.3 Codex leads
GPT-5.3 Codex: 48.0 (#9), GPT-5-Codex: 31.0 (#72)
| Benchmark | GPT-5.3 Codex | GPT-5-Codex |
|---|---|---|
| Terminal-Bench | 78.4% | 44.3% |
| METR Time Horizons | 74.5% | — |
| Vending-Bench 2 | 5,940 | — |
Reasoning Not comparable
GPT-5.3 Codex: —, GPT-5-Codex: 30.9 (#83)
| Benchmark | GPT-5.3 Codex | GPT-5-Codex |
|---|---|---|
| Kagi LLM Benchmark | — | 70.3% |
| Epoch Capabilities Index | 156.77 | — |
Frequently asked questions
Is GPT-5.3 Codex better than GPT-5-Codex?
GPT-5.3 Codex is the stronger model overall, scoring 45.8 to 37.9 on the Noometry Index.
Which is cheaper, GPT-5.3 Codex or GPT-5-Codex?
GPT-5-Codex is cheaper. It lists at $1.25 per million input tokens and $10 per million output tokens; GPT-5.3 Codex lists at $1.75 and $14.
Is GPT-5.3 Codex or GPT-5-Codex better for coding?
GPT-5.3 Codex scores higher on coding benchmarks: 48.6 versus 42.4 in the Noometry coding category.
Which has the bigger context window?
Both accept 400K tokens.
How many benchmarks do GPT-5.3 Codex and GPT-5-Codex share?
2 benchmarks have published results for both models. GPT-5.3 Codex has 8 scored results on Noometry and GPT-5-Codex has 3.