Model comparison
GPT-5.2 Codex vs Step 3.5 Flash
GPT-5.2 Codex and Step 3.5 Flash score almost the same on the Noometry Index (42.6 vs 42.3), so choose on price, context window or the category you care about most.
Last verified . 0 shared benchmarks.
StepFunSummary
- The widest gap is in coding, where GPT-5.2 Codex leads 45.5 to 42.4.
- Step 3.5 Flash is cheaper at $0.10 / $0.30 per million input/output tokens, against $1.75 / $14 for GPT-5.2 Codex.
- GPT-5.2 Codex accepts more context: 400K tokens versus 256K.
- Step 3.5 Flash has downloadable open weights; the other is API-only.
Side by side
| GPT-5.2 Codex | Step 3.5 Flash | |
|---|---|---|
| Provider | OpenAI | StepFun |
| Noometry Index | 42.6 | 42.3 |
| Released | 2025-12-18 | 2026-01-29 |
| Weights | Proprietary | Open |
| Context window | 400K | 256K |
| Max output | 128K | 256K |
| Input $ / M tokens | $1.75 | $0.10 |
| Output $ / M tokens | $14 | $0.30 |
| Results tracked | 5 | 19 |
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Category by category
Coding GPT-5.2 Codex leads
GPT-5.2 Codex: 45.5 (#71), Step 3.5 Flash: 42.4 (#105)
| Benchmark | GPT-5.2 Codex | Step 3.5 Flash |
|---|---|---|
| SWE-bench Verified (bash only) | 72.8% | — |
| LMArena WebDev | 1339 | — |
| SWE-bench Multilingual | 66.3% | — |
| LMArena Coding | — | 1436 |
| ALE-Bench | 1,300 | — |
Agentic & Tool Use Not comparable
GPT-5.2 Codex: 41.0 (#22), Step 3.5 Flash: —
| Benchmark | GPT-5.2 Codex | Step 3.5 Flash |
|---|---|---|
| Terminal-Bench | 66.5% | — |
Reasoning Not comparable
GPT-5.2 Codex: —, Step 3.5 Flash: 22.2 (#202)
| Benchmark | GPT-5.2 Codex | Step 3.5 Flash |
|---|---|---|
| NYT Connections (extended) | — | 28.4% |
| LMArena Hard Prompts | — | 1411 |
Math Not comparable
GPT-5.2 Codex: —, Step 3.5 Flash: 42.6 (#84)
| Benchmark | GPT-5.2 Codex | Step 3.5 Flash |
|---|---|---|
| MathArena Final-Answer Competitions | — | 66.8% |
| LMArena Math | — | 1408 |
Knowledge Not comparable
GPT-5.2 Codex: —, Step 3.5 Flash: 39.6 (#132)
| Benchmark | GPT-5.2 Codex | Step 3.5 Flash |
|---|---|---|
| LMArena Expert | — | 1421 |
Multilingual Not comparable
GPT-5.2 Codex: —, Step 3.5 Flash: 50.5 (#119)
| Benchmark | GPT-5.2 Codex | Step 3.5 Flash |
|---|---|---|
| LMArena Non-English | — | 1385 |
| LMArena Chinese | — | 1447 |
| LMArena French | — | 1421 |
| LMArena German | — | 1405 |
| LMArena Japanese | — | 1354 |
| LMArena Korean | — | 1352 |
| LMArena Russian | — | 1385 |
| LMArena Spanish | — | 1419 |
Instruction Following Not comparable
GPT-5.2 Codex: —, Step 3.5 Flash: 73.1 (#124)
| Benchmark | GPT-5.2 Codex | Step 3.5 Flash |
|---|---|---|
| LMArena Instruction Following | — | 1385 |
Long Context Not comparable
GPT-5.2 Codex: —, Step 3.5 Flash: 42.8 (#117)
| Benchmark | GPT-5.2 Codex | Step 3.5 Flash |
|---|---|---|
| LMArena Longer Query | — | 1402 |
Writing & Preference Not comparable
GPT-5.2 Codex: —, Step 3.5 Flash: 58.8 (#113)
| Benchmark | GPT-5.2 Codex | Step 3.5 Flash |
|---|---|---|
| LMArena Text | — | 1403 |
| LMArena Creative Writing | — | 1357 |
| LMArena Multi-Turn | — | 1405 |
Frequently asked questions
Is GPT-5.2 Codex better than Step 3.5 Flash?
GPT-5.2 Codex and Step 3.5 Flash score almost the same on the Noometry Index (42.6 vs 42.3), so choose on price, context window or the category you care about most.
Which is cheaper, GPT-5.2 Codex or Step 3.5 Flash?
Step 3.5 Flash is cheaper. It lists at $0.10 per million input tokens and $0.30 per million output tokens; GPT-5.2 Codex lists at $1.75 and $14.
Is GPT-5.2 Codex or Step 3.5 Flash better for coding?
GPT-5.2 Codex scores higher on coding benchmarks: 45.5 versus 42.4 in the Noometry coding category.
Which has the bigger context window?
GPT-5.2 Codex does, with 400K tokens against 256K.
How many benchmarks do GPT-5.2 Codex and Step 3.5 Flash share?
0 benchmarks have published results for both models. GPT-5.2 Codex has 5 scored results on Noometry and Step 3.5 Flash has 19.