Model comparison
GPT-5.3 Codex vs Step 3.7 Flash
GPT-5.3 Codex is the stronger model overall, scoring 45.8 to 37.3 on the Noometry Index. Step 3.7 Flash costs 12× less per token, which makes it the better buy when GPT-5.3 Codex's lead doesn't matter for your workload.
Last verified . 1 shared benchmarks.
StepFunSummary
- They share 1 benchmark with published results for both. GPT-5.3 Codex scores higher in 1 category and Step 3.7 Flash in 0 categories; one gap is clear of the uncertainty.
- The widest gap is in coding, where GPT-5.3 Codex leads 48.6 to 40.0.
- Step 3.7 Flash is cheaper at $0.18 / $1.11 per million input/output tokens, against $1.75 / $14 for GPT-5.3 Codex.
- GPT-5.3 Codex accepts more context: 400K tokens versus 256K.
- Step 3.7 Flash has downloadable open weights; the other is API-only.
Side by side
| GPT-5.3 Codex | Step 3.7 Flash | |
|---|---|---|
| Provider | OpenAI | StepFun |
| Noometry Index | 45.8 | 37.3 |
| Released | 2026-02-05 | 2026-05-29 |
| Weights | Proprietary | Open |
| Context window | 400K | 256K |
| Max output | 128K | 256K |
| Input $ / M tokens | $1.75 | $0.18 |
| Output $ / M tokens | $14 | $1.11 |
| Results tracked | 8 | 5 |
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Category by category
Coding GPT-5.3 Codex leads
GPT-5.3 Codex: 48.6 (#56), Step 3.7 Flash: 40.0 (#150)
| Benchmark | GPT-5.3 Codex | Step 3.7 Flash |
|---|---|---|
| ALE-Bench | 1,655 | 694.12 |
| SWE-bench Verified | 74.8% | — |
| LMArena WebDev | 1409 | — |
| SciCode | — | 40% |
| WeirdML | 79.3% | — |
Agentic & Tool Use Not comparable
GPT-5.3 Codex: 48.0 (#9), Step 3.7 Flash: —
| Benchmark | GPT-5.3 Codex | Step 3.7 Flash |
|---|---|---|
| Terminal-Bench | 78.4% | — |
| METR Time Horizons | 74.5% | — |
| Vending-Bench 2 | 5,940 | — |
Reasoning Not comparable
GPT-5.3 Codex: —, Step 3.7 Flash: 21.6 (#219)
| Benchmark | GPT-5.3 Codex | Step 3.7 Flash |
|---|---|---|
| NYT Connections (extended) | — | 39.7% |
| CritPt | — | 2.3% |
| Epoch Capabilities Index | 156.77 | — |
Math Not comparable
GPT-5.3 Codex: —, Step 3.7 Flash: 42.9 (#82)
| Benchmark | GPT-5.3 Codex | Step 3.7 Flash |
|---|---|---|
| MathArena Final-Answer Competitions | — | 68.5% |
Frequently asked questions
Is GPT-5.3 Codex better than Step 3.7 Flash?
GPT-5.3 Codex is the stronger model overall, scoring 45.8 to 37.3 on the Noometry Index. Step 3.7 Flash costs 12× less per token, which makes it the better buy when GPT-5.3 Codex's lead doesn't matter for your workload.
Which is cheaper, GPT-5.3 Codex or Step 3.7 Flash?
Step 3.7 Flash is cheaper. It lists at $0.18 per million input tokens and $1.11 per million output tokens; GPT-5.3 Codex lists at $1.75 and $14.
Is GPT-5.3 Codex or Step 3.7 Flash better for coding?
GPT-5.3 Codex scores higher on coding benchmarks: 48.6 versus 40.0 in the Noometry coding category.
Which has the bigger context window?
GPT-5.3 Codex does, with 400K tokens against 256K.
How many benchmarks do GPT-5.3 Codex and Step 3.7 Flash share?
1 benchmark has published results for both models. GPT-5.3 Codex has 8 scored results on Noometry and Step 3.7 Flash has 5.