Model comparison
GPT-5.4 nano vs GPT-5-Codex
GPT-5.4 nano is the stronger model overall, scoring 41.9 to 37.9 on the Noometry Index.
Last verified . 2 shared benchmarks.
Summary
- They share 2 benchmarks with published results for both. GPT-5.4 nano scores higher in 1 category and GPT-5-Codex in 1 category; 2 gaps are clear of the uncertainty.
- The widest gap is in reasoning, where GPT-5-Codex leads 30.9 to 23.7.
- The biggest single-benchmark swing is Kagi LLM Benchmark: 39.7% for GPT-5.4 nano and 70.3% for GPT-5-Codex.
- GPT-5.4 nano is cheaper at $0.20 / $1.25 per million input/output tokens, against $1.25 / $10 for GPT-5-Codex.
Side by side
| GPT-5.4 nano | GPT-5-Codex | |
|---|---|---|
| Provider | OpenAI | OpenAI |
| Noometry Index | 41.9 | 37.9 |
| Released | 2026-03-17 | 2025-09-15 |
| Weights | Proprietary | Proprietary |
| Context window | 400K | 400K |
| Max output | 128K | 128K |
| Input $ / M tokens | $0.20 | $1.25 |
| Output $ / M tokens | $1.25 | $10 |
| Results tracked | 40 | 3 |
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Category by category
Coding GPT-5.4 nano leads
GPT-5.4 nano: 43.6 (#84), GPT-5-Codex: 42.4 (#103)
| Benchmark | GPT-5.4 nano | GPT-5-Codex |
|---|---|---|
| WeirdML | 49.2% | 54.5% |
| SciCode | 46.9% | — |
| LMArena Coding | 1405 | — |
| ALE-Bench | 1,005 | — |
Agentic & Tool Use Not comparable
GPT-5.4 nano: —, GPT-5-Codex: 31.0 (#72)
| Benchmark | GPT-5.4 nano | GPT-5-Codex |
|---|---|---|
| Terminal-Bench | — | 44.3% |
Reasoning GPT-5-Codex leads
GPT-5.4 nano: 23.7 (#173), GPT-5-Codex: 30.9 (#83)
| Benchmark | GPT-5.4 nano | GPT-5-Codex |
|---|---|---|
| Kagi LLM Benchmark | 39.7% | 70.3% |
| ARC-AGI-2 | 5.7% | — |
| ARC-AGI-1 | 51.5% | — |
| CritPt | 9.3% | — |
| Chess Puzzles | 30% | — |
| LMArena Hard Prompts | 1381 | — |
| Mystery Game Puzzles | 9% | — |
| DTBench | 80.3% | — |
| LMCA | 36.9% | — |
| Epoch Capabilities Index | 145.81 | — |
| ForecastBench | 57.3 | — |
Math Not comparable
GPT-5.4 nano: 40.9 (#88), GPT-5-Codex: —
| Benchmark | GPT-5.4 nano | GPT-5-Codex |
|---|---|---|
| FrontierMath (Tiers 1-3) | 44.9% | — |
| FrontierMath Tier 4 | 12.2% | — |
| OTIS Mock AIME 2024-2025 | 87.8% | — |
| ProofBench | 5% | — |
| LMArena Math | 1406 | — |
| FrontierMath (Feb 2025 set) | 25.9% | — |
| FrontierMath Tier 4 (v1) | 6.3% | — |
Knowledge Not comparable
GPT-5.4 nano: 41.9 (#103), GPT-5-Codex: —
| Benchmark | GPT-5.4 nano | GPT-5-Codex |
|---|---|---|
| GPQA Diamond | 78.5% | — |
| SimpleQA Verified | 11.7% | — |
| Vectara Hallucination Rate | 3.1% | — |
| LMArena Expert | 1396 | — |
Multimodal Not comparable
GPT-5.4 nano: 36.7 (#78), GPT-5-Codex: —
| Benchmark | GPT-5.4 nano | GPT-5-Codex |
|---|---|---|
| LMArena Vision | 1196 | — |
Multilingual Not comparable
GPT-5.4 nano: 48.6 (#140), GPT-5-Codex: —
| Benchmark | GPT-5.4 nano | GPT-5-Codex |
|---|---|---|
| LMArena Non-English | 1359 | — |
| LMArena Chinese | 1392 | — |
| LMArena French | 1396 | — |
| LMArena German | 1367 | — |
| LMArena Japanese | 1343 | — |
| LMArena Korean | 1320 | — |
| LMArena Russian | 1363 | — |
| LMArena Spanish | 1371 | — |
Instruction Following Not comparable
GPT-5.4 nano: 71.9 (#144), GPT-5-Codex: —
| Benchmark | GPT-5.4 nano | GPT-5-Codex |
|---|---|---|
| LMArena Instruction Following | 1362 | — |
Long Context Not comparable
GPT-5.4 nano: 41.6 (#137), GPT-5-Codex: —
| Benchmark | GPT-5.4 nano | GPT-5-Codex |
|---|---|---|
| LMArena Longer Query | 1366 | — |
Writing & Preference Not comparable
GPT-5.4 nano: 55.7 (#142), GPT-5-Codex: —
| Benchmark | GPT-5.4 nano | GPT-5-Codex |
|---|---|---|
| LMArena Text | 1372 | — |
| LMArena Creative Writing | 1314 | — |
| LMArena Multi-Turn | 1382 | — |
Frequently asked questions
Is GPT-5.4 nano better than GPT-5-Codex?
GPT-5.4 nano is the stronger model overall, scoring 41.9 to 37.9 on the Noometry Index.
Which is cheaper, GPT-5.4 nano or GPT-5-Codex?
GPT-5.4 nano is cheaper. It lists at $0.20 per million input tokens and $1.25 per million output tokens; GPT-5-Codex lists at $1.25 and $10.
Is GPT-5.4 nano or GPT-5-Codex better for coding?
GPT-5.4 nano scores higher on coding benchmarks: 43.6 versus 42.4 in the Noometry coding category.
Which has the bigger context window?
Both accept 400K tokens.
How many benchmarks do GPT-5.4 nano and GPT-5-Codex share?
2 benchmarks have published results for both models. GPT-5.4 nano has 40 scored results on Noometry and GPT-5-Codex has 3.