Model comparison
gpt-oss-120b vs gpt-oss-20b
gpt-oss-120b is the stronger model overall, scoring 36.0 to 32.1 on the Noometry Index. gpt-oss-20b costs 2.0× less per token, which makes it the better buy when gpt-oss-120b's lead doesn't matter for your workload.
Last verified . 34 shared benchmarks.
Summary
- They share 34 benchmarks with published results for both. gpt-oss-120b scores higher in 7 categories and gpt-oss-20b in 2 categories; 8 gaps are clear of the uncertainty.
- The widest gap is in math, where gpt-oss-120b leads 50.6 to 37.6.
- The biggest single-benchmark swing is OTIS Mock AIME 2024-2025: 88.9% for gpt-oss-120b and 65.3% for gpt-oss-20b.
- gpt-oss-20b is cheaper at $0.018 / $0.09 per million input/output tokens, against $0.037 / $0.17 for gpt-oss-120b.
Side by side
| gpt-oss-120b | gpt-oss-20b | |
|---|---|---|
| Provider | OpenAI | OpenAI |
| Noometry Index | 36.0 | 32.1 |
| Released | 2025-08-05 | 2025-08-05 |
| Weights | Open | Open |
| Context window | 131K | 131K |
| Max output | 41K | 16K |
| Input $ / M tokens | $0.037 | $0.018 |
| Output $ / M tokens | $0.17 | $0.09 |
| Results tracked | 48 | 34 |
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Category by category
Coding gpt-oss-20b leads
gpt-oss-120b: 33.2 (#251), gpt-oss-20b: 37.1 (#185)
| Benchmark | gpt-oss-120b | gpt-oss-20b |
|---|---|---|
| SciCode | 36% | 34.4% |
| WeirdML | 48.2% | 40.9% |
| LMArena Coding | 1380 | 1307 |
| ALE-Bench | 575.62 | 566.05 |
| SWE-bench Verified (bash only) | 26% | — |
| Aider Polyglot | 41.8% | — |
| AlgoTune | 1.41 | — |
Agentic & Tool Use gpt-oss-120b leads
gpt-oss-120b: 12.1 (#145), gpt-oss-20b: 9.2 (#146)
| Benchmark | gpt-oss-120b | gpt-oss-20b |
|---|---|---|
| Terminal-Bench | 18.7% | 3.4% |
| APEX-Agents | 4.4% | — |
| METR Time Horizons | 56.6% | — |
| Vending-Bench 2 | -21.53 | — |
Reasoning Too close to call
gpt-oss-120b: 19.5 (#236), gpt-oss-20b: 18.8 (#251)
| Benchmark | gpt-oss-120b | gpt-oss-20b |
|---|---|---|
| Kagi LLM Benchmark | 58.6% | 53.2% |
| CritPt | 1.1% | 1.4% |
| Chess Puzzles | 20% | 4% |
| LMArena Hard Prompts | 1364 | 1274 |
| DTBench | 76.3% | 68% |
| LMCA | 22.1% | 14.5% |
| Epoch Capabilities Index | 139.94 | 137.81 |
| SimpleBench | 22.1% | — |
| Mystery Game Puzzles | 2% | — |
| Surface Evolver Bench | 25% | — |
Math gpt-oss-120b leads
gpt-oss-120b: 50.6 (#43), gpt-oss-20b: 37.6 (#93)
| Benchmark | gpt-oss-120b | gpt-oss-20b |
|---|---|---|
| OTIS Mock AIME 2024-2025 | 88.9% | 65.3% |
| Omni-MATH | 68.8% | 56.5% |
| LMArena Math | 1388 | 1317 |
Knowledge gpt-oss-120b leads
gpt-oss-120b: 42.3 (#89), gpt-oss-20b: 34.6 (#186)
| Benchmark | gpt-oss-120b | gpt-oss-20b |
|---|---|---|
| GPQA Diamond | 75.8% | 60.8% |
| MMLU-Pro | 79.5% | 74% |
| GPQA (HELM) | 68.4% | 59.4% |
| LMArena Expert | 1356 | 1258 |
| Confabulations | 15.7% | — |
| Vectara Hallucination Rate | 14.2% | — |
Multilingual gpt-oss-120b leads
gpt-oss-120b: 48.2 (#142), gpt-oss-20b: 42.4 (#192)
| Benchmark | gpt-oss-120b | gpt-oss-20b |
|---|---|---|
| LMArena Non-English | 1350 | 1269 |
| LMArena Chinese | 1384 | 1311 |
| LMArena German | 1355 | 1249 |
| LMArena Japanese | 1332 | 1245 |
| LMArena Korean | 1283 | 1239 |
| LMArena Russian | 1343 | 1279 |
| LMArena Spanish | 1388 | 1267 |
| LMArena French | 1370 | — |
Instruction Following gpt-oss-120b leads
gpt-oss-120b: 69.5 (#168), gpt-oss-20b: 62.0 (#235)
| Benchmark | gpt-oss-120b | gpt-oss-20b |
|---|---|---|
| IFEval | 83.6% | 73.2% |
| LMArena Instruction Following | 1318 | 1236 |
Long Context gpt-oss-20b leads
gpt-oss-120b: 31.4 (#273), gpt-oss-20b: 37.9 (#203)
| Benchmark | gpt-oss-120b | gpt-oss-20b |
|---|---|---|
| LMArena Longer Query | 1319 | 1251 |
| Fiction.LiveBench | 44.4% | — |
Writing & Preference gpt-oss-120b leads
gpt-oss-120b: 46.7 (#213), gpt-oss-20b: 35.8 (#260)
| Benchmark | gpt-oss-120b | gpt-oss-20b |
|---|---|---|
| LMArena Text | 1366 | 1288 |
| LMArena Creative Writing | 1274 | 1201 |
| EQ-Bench Creative Writing | 961 | 666 |
| WildBench | 84.5% | 73.7% |
| LMArena Multi-Turn | 1340 | 1268 |
| Short-Story Creative Writing | 77.1% | — |
Frequently asked questions
Is gpt-oss-120b better than gpt-oss-20b?
gpt-oss-120b is the stronger model overall, scoring 36.0 to 32.1 on the Noometry Index. gpt-oss-20b costs 2.0× less per token, which makes it the better buy when gpt-oss-120b's lead doesn't matter for your workload.
Which is cheaper, gpt-oss-120b or gpt-oss-20b?
gpt-oss-20b is cheaper. It lists at $0.018 per million input tokens and $0.09 per million output tokens; gpt-oss-120b lists at $0.037 and $0.17.
Is gpt-oss-120b or gpt-oss-20b better for coding?
gpt-oss-20b scores higher on coding benchmarks: 37.1 versus 33.2 in the Noometry coding category.
Which has the bigger context window?
Both accept 131K tokens.
How many benchmarks do gpt-oss-120b and gpt-oss-20b share?
34 benchmarks have published results for both models. gpt-oss-120b has 48 scored results on Noometry and gpt-oss-20b has 34.