Model comparison
GPT-5.1-Codex vs Step 3.7 Flash
GPT-5.1-Codex is the stronger model overall, scoring 38.2 to 36.5 on the Noometry Index. Step 3.7 Flash costs 8.3× less per token, which makes it the better buy when GPT-5.1-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-5.1-Codex scores higher in 1 category and Step 3.7 Flash in 1 category; 2 gaps are clear of the uncertainty.
- The widest gap is in math, where Step 3.7 Flash leads 40.9 to 29.3.
- Step 3.7 Flash is cheaper at $0.18 / $1.11 per million input/output tokens, against $1.25 / $10 for GPT-5.1-Codex.
- GPT-5.1-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-5.1-Codex | Step 3.7 Flash | |
|---|---|---|
| Provider | OpenAI | StepFun |
| Noometry Index | 38.2 | 36.5 |
| Released | 2025-11-12 | 2026-05-29 |
| Weights | Proprietary | Open |
| Context window | 400K | 256K |
| Max output | 128K | 256K |
| Input $ / M tokens | $1.25 | $0.18 |
| Output $ / M tokens | $10 | $1.11 |
| Results tracked | 6 | 5 |
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Category by category
Coding GPT-5.1-Codex leads
GPT-5.1-Codex: 41.7 (#107), Step 3.7 Flash: 39.4 (#147)
| Benchmark | GPT-5.1-Codex | Step 3.7 Flash |
|---|---|---|
| ALE-Bench | 1,245 | 694.12 |
| SWE-bench Verified (bash only) | 66% | — |
| LMArena WebDev | 1337 | — |
| SciCode | — | 40% |
Agentic & Tool Use Not comparable
GPT-5.1-Codex: 37.8 (#32), Step 3.7 Flash: —
| Benchmark | GPT-5.1-Codex | Step 3.7 Flash |
|---|---|---|
| Terminal-Bench | 60.4% | — |
| METR Time Horizons | 70.8% | — |
Reasoning Not comparable
GPT-5.1-Codex: —, Step 3.7 Flash: 20.9 (#211)
| Benchmark | GPT-5.1-Codex | Step 3.7 Flash |
|---|---|---|
| NYT Connections (extended) | — | 39.7% |
| CritPt | — | 2.3% |
Math Step 3.7 Flash leads
GPT-5.1-Codex: 29.3 (#218), Step 3.7 Flash: 40.9 (#74)
| Benchmark | GPT-5.1-Codex | Step 3.7 Flash |
|---|---|---|
| MathArena Final-Answer Competitions | — | 68.5% |
| ProofBench | 9% | — |
Frequently asked questions
Is GPT-5.1-Codex better than Step 3.7 Flash?
GPT-5.1-Codex is the stronger model overall, scoring 38.2 to 36.5 on the Noometry Index. Step 3.7 Flash costs 8.3× less per token, which makes it the better buy when GPT-5.1-Codex's lead doesn't matter for your workload.
Which is cheaper, GPT-5.1-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-5.1-Codex lists at $1.25 and $10.
Is GPT-5.1-Codex or Step 3.7 Flash better for coding?
GPT-5.1-Codex scores higher on coding benchmarks: 41.7 versus 39.4 in the Noometry coding category.
Which has the bigger context window?
GPT-5.1-Codex does, with 400K tokens against 256K.
How many benchmarks do GPT-5.1-Codex and Step 3.7 Flash share?
1 benchmark has published results for both models. GPT-5.1-Codex has 6 scored results on Noometry and Step 3.7 Flash has 5.