Model comparison
GPT-5.3 Chat vs Step 3.7 Flash
GPT-5.3 Chat is the stronger model overall, scoring 42.1 to 36.5 on the Noometry Index. Step 3.7 Flash costs 12× less per token, which makes it the better buy when GPT-5.3 Chat's lead doesn't matter for your workload.
Last verified . 0 shared benchmarks.
StepFunSummary
- The widest gap is in reasoning, where GPT-5.3 Chat leads 27.3 to 20.9.
- Step 3.7 Flash is cheaper at $0.18 / $1.11 per million input/output tokens, against $1.75 / $14 for GPT-5.3 Chat.
- Step 3.7 Flash accepts more context: 256K tokens versus 128K.
- Step 3.7 Flash has downloadable open weights; the other is API-only.
Side by side
| GPT-5.3 Chat | Step 3.7 Flash | |
|---|---|---|
| Provider | OpenAI | StepFun |
| Noometry Index | 42.1 | 36.5 |
| Released | 2026-03-03 | 2026-05-29 |
| Weights | Proprietary | Open |
| Context window | 128K | 256K |
| Max output | 16K | 256K |
| Input $ / M tokens | $1.75 | $0.18 |
| Output $ / M tokens | $14 | $1.11 |
| Results tracked | 18 | 5 |
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Category by category
Coding GPT-5.3 Chat leads
GPT-5.3 Chat: 40.8 (#124), Step 3.7 Flash: 39.4 (#147)
| Benchmark | GPT-5.3 Chat | Step 3.7 Flash |
|---|---|---|
| SciCode | — | 40% |
| LMArena Coding | 1408 | — |
| ALE-Bench | — | 694.12 |
Reasoning GPT-5.3 Chat leads
GPT-5.3 Chat: 27.3 (#105), Step 3.7 Flash: 20.9 (#211)
| Benchmark | GPT-5.3 Chat | Step 3.7 Flash |
|---|---|---|
| NYT Connections (extended) | — | 39.7% |
| CritPt | — | 2.3% |
| LMArena Hard Prompts | 1399 | — |
Math Step 3.7 Flash leads
GPT-5.3 Chat: 35.4 (#146), Step 3.7 Flash: 40.9 (#74)
| Benchmark | GPT-5.3 Chat | Step 3.7 Flash |
|---|---|---|
| MathArena Final-Answer Competitions | — | 68.5% |
| LMArena Math | 1389 | — |
Knowledge Not comparable
GPT-5.3 Chat: 38.2 (#137), Step 3.7 Flash: —
| Benchmark | GPT-5.3 Chat | Step 3.7 Flash |
|---|---|---|
| LMArena Expert | 1397 | — |
Multilingual Not comparable
GPT-5.3 Chat: 50.5 (#119), Step 3.7 Flash: —
| Benchmark | GPT-5.3 Chat | Step 3.7 Flash |
|---|---|---|
| LMArena Non-English | 1383 | — |
| LMArena Chinese | 1433 | — |
| LMArena French | 1398 | — |
| LMArena German | 1384 | — |
| LMArena Japanese | 1351 | — |
| LMArena Korean | 1347 | — |
| LMArena Russian | 1400 | — |
| LMArena Spanish | 1371 | — |
Instruction Following Not comparable
GPT-5.3 Chat: 73.0 (#124), Step 3.7 Flash: —
| Benchmark | GPT-5.3 Chat | Step 3.7 Flash |
|---|---|---|
| LMArena Instruction Following | 1378 | — |
Long Context Not comparable
GPT-5.3 Chat: 42.6 (#115), Step 3.7 Flash: —
| Benchmark | GPT-5.3 Chat | Step 3.7 Flash |
|---|---|---|
| LMArena Longer Query | 1396 | — |
Writing & Preference Not comparable
GPT-5.3 Chat: 63.3 (#65), Step 3.7 Flash: —
| Benchmark | GPT-5.3 Chat | Step 3.7 Flash |
|---|---|---|
| LMArena Text | 1389 | — |
| LMArena Creative Writing | 1356 | — |
| EQ-Bench Creative Writing | 1690 | — |
| LMArena Multi-Turn | 1413 | — |
Frequently asked questions
Is GPT-5.3 Chat better than Step 3.7 Flash?
GPT-5.3 Chat is the stronger model overall, scoring 42.1 to 36.5 on the Noometry Index. Step 3.7 Flash costs 12× less per token, which makes it the better buy when GPT-5.3 Chat's lead doesn't matter for your workload.
Which is cheaper, GPT-5.3 Chat 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 Chat lists at $1.75 and $14.
Is GPT-5.3 Chat or Step 3.7 Flash better for coding?
GPT-5.3 Chat scores higher on coding benchmarks: 40.8 versus 39.4 in the Noometry coding category.
Which has the bigger context window?
Step 3.7 Flash does, with 256K tokens against 128K.
How many benchmarks do GPT-5.3 Chat and Step 3.7 Flash share?
0 benchmarks have published results for both models. GPT-5.3 Chat has 18 scored results on Noometry and Step 3.7 Flash has 5.