Model comparison
GPT-5.3 Chat vs Step 2 16k Exp 202412
GPT-5.3 Chat is the stronger model overall, scoring 42.8 to 39.2 on the Noometry Index.
Last verified . 12 shared benchmarks.
StepFunSummary
- They share 12 benchmarks with published results for both. GPT-5.3 Chat scores higher in 8 categories and Step 2 16k Exp 202412 in 0 categories; 8 gaps are clear of the uncertainty.
- The widest gap is in writing & preference, where GPT-5.3 Chat leads 63.1 to 52.3.
Side by side
| GPT-5.3 Chat | Step 2 16k Exp 202412 | |
|---|---|---|
| Provider | OpenAI | StepFun |
| Noometry Index | 42.8 | 39.2 |
| Released | 2026-03-03 | — |
| Weights | Proprietary | Proprietary |
| Context window | 128K | — |
| Max output | 16K | — |
| Input $ / M tokens | $1.75 | — |
| Output $ / M tokens | $14 | — |
| Results tracked | 18 | 12 |
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Category by category
Coding GPT-5.3 Chat leads
GPT-5.3 Chat: 41.4 (#124), Step 2 16k Exp 202412: 38.5 (#174)
| Benchmark | GPT-5.3 Chat | Step 2 16k Exp 202412 |
|---|---|---|
| LMArena Coding | 1408 | 1316 |
Reasoning GPT-5.3 Chat leads
GPT-5.3 Chat: 28.5 (#102), Step 2 16k Exp 202412: 25.9 (#142)
| Benchmark | GPT-5.3 Chat | Step 2 16k Exp 202412 |
|---|---|---|
| LMArena Hard Prompts | 1399 | 1299 |
Math GPT-5.3 Chat leads
GPT-5.3 Chat: 38.2 (#142), Step 2 16k Exp 202412: 36.3 (#169)
| Benchmark | GPT-5.3 Chat | Step 2 16k Exp 202412 |
|---|---|---|
| LMArena Math | 1389 | 1304 |
Knowledge GPT-5.3 Chat leads
GPT-5.3 Chat: 38.8 (#140), Step 2 16k Exp 202412: 35.2 (#187)
| Benchmark | GPT-5.3 Chat | Step 2 16k Exp 202412 |
|---|---|---|
| LMArena Expert | 1397 | 1279 |
Multilingual GPT-5.3 Chat leads
GPT-5.3 Chat: 50.3 (#124), Step 2 16k Exp 202412: 43.7 (#181)
| Benchmark | GPT-5.3 Chat | Step 2 16k Exp 202412 |
|---|---|---|
| LMArena Non-English | 1382 | 1290 |
| LMArena Chinese | 1432 | 1331 |
| LMArena Russian | 1400 | 1324 |
| LMArena French | 1397 | — |
| LMArena German | 1384 | — |
| LMArena Japanese | 1352 | — |
| LMArena Korean | 1346 | — |
| LMArena Spanish | 1371 | — |
Instruction Following GPT-5.3 Chat leads
GPT-5.3 Chat: 72.8 (#129), Step 2 16k Exp 202412: 67.9 (#192)
| Benchmark | GPT-5.3 Chat | Step 2 16k Exp 202412 |
|---|---|---|
| LMArena Instruction Following | 1378 | 1287 |
Long Context GPT-5.3 Chat leads
GPT-5.3 Chat: 42.6 (#120), Step 2 16k Exp 202412: 39.7 (#170)
| Benchmark | GPT-5.3 Chat | Step 2 16k Exp 202412 |
|---|---|---|
| LMArena Longer Query | 1396 | 1307 |
Writing & Preference GPT-5.3 Chat leads
GPT-5.3 Chat: 63.1 (#68), Step 2 16k Exp 202412: 52.3 (#173)
| Benchmark | GPT-5.3 Chat | Step 2 16k Exp 202412 |
|---|---|---|
| LMArena Text | 1389 | 1321 |
| LMArena Creative Writing | 1355 | 1328 |
| LMArena Multi-Turn | 1412 | 1292 |
| EQ-Bench Creative Writing | 1690 | — |
Frequently asked questions
Is GPT-5.3 Chat better than Step 2 16k Exp 202412?
GPT-5.3 Chat is the stronger model overall, scoring 42.8 to 39.2 on the Noometry Index.
Is GPT-5.3 Chat or Step 2 16k Exp 202412 better for coding?
GPT-5.3 Chat scores higher on coding benchmarks: 41.4 versus 38.5 in the Noometry coding category.
How many benchmarks do GPT-5.3 Chat and Step 2 16k Exp 202412 share?
12 benchmarks have published results for both models. GPT-5.3 Chat has 18 scored results on Noometry and Step 2 16k Exp 202412 has 12.