Model comparison
GPT-5.3 Codex vs GPT-5.5 Pro
GPT-5.5 Pro is the stronger model overall, scoring 64.3 to 45.5 on the Noometry Index. GPT-5.3 Codex costs 14× less per token, which makes it the better buy when GPT-5.5 Pro's lead doesn't matter for your workload.
Last verified . 1 shared benchmarks.
Summary
- They share 1 benchmark with published results for both.
- GPT-5.3 Codex is cheaper at $1.75 / $14 per million input/output tokens, against $30 / $180 for GPT-5.5 Pro.
- GPT-5.5 Pro accepts more context: 1.05M tokens versus 400K.
Side by side
| GPT-5.3 Codex | GPT-5.5 Pro | |
|---|---|---|
| Provider | OpenAI | OpenAI |
| Noometry Index | 45.5 | 64.3 |
| Released | 2026-02-05 | 2026-04-23 |
| Weights | Proprietary | Proprietary |
| Context window | 400K | 1.05M |
| Max output | 128K | 128K |
| Input $ / M tokens | $1.75 | $30 |
| Output $ / M tokens | $14 | $180 |
| Results tracked | 8 | 14 |
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Category by category
Coding Not comparable
GPT-5.3 Codex: 48.5 (#51), GPT-5.5 Pro: —
| Benchmark | GPT-5.3 Codex | GPT-5.5 Pro |
|---|---|---|
| SWE-bench Verified | 74.8% | — |
| LMArena WebDev | 1408 | — |
| WeirdML | 79.3% | — |
| ALE-Bench | 1,655 | — |
Agentic & Tool Use Not comparable
GPT-5.3 Codex: 47.8 (#9), GPT-5.5 Pro: —
| Benchmark | GPT-5.3 Codex | GPT-5.5 Pro |
|---|---|---|
| Terminal-Bench | 78.4% | — |
| METR Time Horizons | 74.5% | — |
| Vending-Bench 2 | 5,940 | — |
Reasoning Not comparable
GPT-5.3 Codex: —, GPT-5.5 Pro: 73.6 (#7)
| Benchmark | GPT-5.3 Codex | GPT-5.5 Pro |
|---|---|---|
| Epoch Capabilities Index | 156.84 | 162.45 |
| ARC-AGI-2 | — | 84.6% |
| SimpleBench | — | 76.9% |
| ARC-AGI-1 | — | 96.5% |
| CritPt | — | 30.6% |
| Chess Puzzles | — | 64% |
| DTBench | — | 96% |
| LMCA | — | 53.9% |
Math Not comparable
GPT-5.3 Codex: —, GPT-5.5 Pro: 83.8 (#8)
| Benchmark | GPT-5.3 Codex | GPT-5.5 Pro |
|---|---|---|
| FrontierMath (Tiers 1-3) | — | 87.7% |
| FrontierMath Tier 4 | — | 78% |
| OTIS Mock AIME 2024-2025 | — | 100% |
| FrontierMath (Feb 2025 set) | — | 52.4% |
| FrontierMath Tier 4 (v1) | — | 39.6% |
Knowledge Not comparable
GPT-5.3 Codex: —, GPT-5.5 Pro: 64.2 (#17)
| Benchmark | GPT-5.3 Codex | GPT-5.5 Pro |
|---|---|---|
| GPQA Diamond | — | 93.9% |
Frequently asked questions
Is GPT-5.3 Codex better than GPT-5.5 Pro?
GPT-5.5 Pro is the stronger model overall, scoring 64.3 to 45.5 on the Noometry Index. GPT-5.3 Codex costs 14× less per token, which makes it the better buy when GPT-5.5 Pro's lead doesn't matter for your workload.
Which is cheaper, GPT-5.3 Codex or GPT-5.5 Pro?
GPT-5.3 Codex is cheaper. It lists at $1.75 per million input tokens and $14 per million output tokens; GPT-5.5 Pro lists at $30 and $180.
Which has the bigger context window?
GPT-5.5 Pro does, with 1.05M tokens against 400K.
How many benchmarks do GPT-5.3 Codex and GPT-5.5 Pro share?
1 benchmark has published results for both models. GPT-5.3 Codex has 8 scored results on Noometry and GPT-5.5 Pro has 14.