Model comparison
Claude Sonnet 4 vs gpt-oss-20b
Claude Sonnet 4 is the stronger model overall, scoring 40.8 to 32.5 on the Noometry Index. gpt-oss-20b costs 167× less per token, which makes it the better buy when Claude Sonnet 4's lead doesn't matter for your workload.
Last verified . 32 shared benchmarks.
Summary
- They share 32 benchmarks with published results for both. Claude Sonnet 4 scores higher in 8 categories and gpt-oss-20b in 1 category; 9 gaps are clear of the uncertainty.
- The widest gap is in agentic & tool use, where Claude Sonnet 4 leads 38.5 to 9.3.
- The biggest single-benchmark swing is Kagi LLM Benchmark: 73% for Claude Sonnet 4 and 53.2% for gpt-oss-20b.
- gpt-oss-20b is cheaper at $0.018 / $0.09 per million input/output tokens, against $3 / $15 for Claude Sonnet 4.
- Claude Sonnet 4 accepts more context: 200K tokens versus 131K.
- gpt-oss-20b has downloadable open weights; the other is API-only.
Side by side
| Claude Sonnet 4 | gpt-oss-20b | |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Noometry Index | 40.8 | 32.5 |
| Released | 2025-05-22 | 2025-08-05 |
| Weights | Proprietary | Open |
| Context window | 200K | 131K |
| Max output | 64K | 16K |
| Input $ / M tokens | $3 | $0.018 |
| Output $ / M tokens | $15 | $0.09 |
| Results tracked | 58 | 34 |
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Category by category
Coding Claude Sonnet 4 leads
Claude Sonnet 4: 43.5 (#88), gpt-oss-20b: 37.6 (#192)
| Benchmark | Claude Sonnet 4 | gpt-oss-20b |
|---|---|---|
| SciCode | 40% | 34.4% |
| WeirdML | 46.1% | 40.9% |
| LMArena Coding | 1414 | 1306 |
| ALE-Bench | 655.35 | 566.05 |
| SWE-bench Verified (bash only) | 64.9% | — |
| Aider Polyglot | 61.3% | — |
| GSO | 4.9% | — |
Agentic & Tool Use Claude Sonnet 4 leads
Claude Sonnet 4: 38.5 (#31), gpt-oss-20b: 9.3 (#154)
| Benchmark | Claude Sonnet 4 | gpt-oss-20b |
|---|---|---|
| Terminal-Bench | — | 3.4% |
| TheAgentCompany | 33.1% | — |
| Cybench | 35% | — |
| DeepResearch Bench | 46.6% | — |
| OSWorld | 43.9% | — |
| METR Time Horizons | 62% | — |
Reasoning Claude Sonnet 4 leads
Claude Sonnet 4: 22.9 (#187), gpt-oss-20b: 19.3 (#261)
| Benchmark | Claude Sonnet 4 | gpt-oss-20b |
|---|---|---|
| Kagi LLM Benchmark | 73% | 53.2% |
| CritPt | 0.3% | 1.4% |
| LMArena Hard Prompts | 1372 | 1274 |
| DTBench | 77.1% | 68% |
| LMCA | 29% | 14.5% |
| Epoch Capabilities Index | 141.69 | 137.82 |
| ARC-AGI-2 | 5.9% | — |
| SimpleBench | 45.5% | — |
| ARC-AGI-1 | 40% | — |
| Chess Puzzles | — | 4% |
| EnigmaEval | 3.1% | — |
| ForecastBench | 60.2 | — |
Math Claude Sonnet 4 leads
Claude Sonnet 4: 43.3 (#80), gpt-oss-20b: 39.4 (#103)
| Benchmark | Claude Sonnet 4 | gpt-oss-20b |
|---|---|---|
| OTIS Mock AIME 2024-2025 | 71.1% | 65.3% |
| Omni-MATH | 60.2% | 56.5% |
| LMArena Math | 1375 | 1317 |
| MATH Level 5 | 84.4% | — |
| FrontierMath (Feb 2025 set) | 4.1% | — |
| FrontierMath Tier 4 (v1) | 0% | — |
Knowledge Claude Sonnet 4 leads
Claude Sonnet 4: 41.8 (#108), gpt-oss-20b: 34.6 (#195)
| Benchmark | Claude Sonnet 4 | gpt-oss-20b |
|---|---|---|
| GPQA Diamond | 79.2% | 60.8% |
| MMLU-Pro | 84.3% | 74% |
| GPQA (HELM) | 70.6% | 59.4% |
| LMArena Expert | 1372 | 1258 |
| Humanity's Last Exam | 7.8% | — |
| Confabulations | 13.2% | — |
| Vectara Hallucination Rate | 10.3% | — |
Multimodal Not comparable
Claude Sonnet 4: 26.2 (#121), gpt-oss-20b: —
| Benchmark | Claude Sonnet 4 | gpt-oss-20b |
|---|---|---|
| LMArena Vision | 1191 | — |
| GeoBench | 37% | — |
| VPCT | 34% | — |
| MindCube | 44.8% | — |
Multilingual Claude Sonnet 4 leads
Claude Sonnet 4: 46.7 (#156), gpt-oss-20b: 42.2 (#197)
| Benchmark | Claude Sonnet 4 | gpt-oss-20b |
|---|---|---|
| LMArena Non-English | 1333 | 1268 |
| LMArena Chinese | 1350 | 1314 |
| LMArena German | 1331 | 1255 |
| LMArena Japanese | 1302 | 1244 |
| LMArena Korean | 1291 | 1236 |
| LMArena Russian | 1355 | 1278 |
| LMArena Spanish | 1357 | 1267 |
| LMArena French | 1363 | — |
Instruction Following Claude Sonnet 4 leads
Claude Sonnet 4: 71.7 (#145), gpt-oss-20b: 61.8 (#240)
| Benchmark | Claude Sonnet 4 | gpt-oss-20b |
|---|---|---|
| IFEval | 84% | 73.2% |
| LMArena Instruction Following | 1376 | 1236 |
Long Context gpt-oss-20b leads
Claude Sonnet 4: 33.7 (#259), gpt-oss-20b: 37.9 (#209)
| Benchmark | Claude Sonnet 4 | gpt-oss-20b |
|---|---|---|
| LMArena Longer Query | 1398 | 1250 |
| Fiction.LiveBench | 46.9% | — |
Writing & Preference Claude Sonnet 4 leads
Claude Sonnet 4: 57.1 (#132), gpt-oss-20b: 35.5 (#265)
| Benchmark | Claude Sonnet 4 | gpt-oss-20b |
|---|---|---|
| LMArena Text | 1351 | 1287 |
| LMArena Creative Writing | 1345 | 1201 |
| EQ-Bench Creative Writing | 1483 | 666 |
| WildBench | 83.8% | 73.7% |
| LMArena Multi-Turn | 1376 | 1268 |
| Short-Story Creative Writing | 81.4% | — |
Frequently asked questions
Is Claude Sonnet 4 better than gpt-oss-20b?
Claude Sonnet 4 is the stronger model overall, scoring 40.8 to 32.5 on the Noometry Index. gpt-oss-20b costs 167× less per token, which makes it the better buy when Claude Sonnet 4's lead doesn't matter for your workload.
Which is cheaper, Claude Sonnet 4 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; Claude Sonnet 4 lists at $3 and $15.
Is Claude Sonnet 4 or gpt-oss-20b better for coding?
Claude Sonnet 4 scores higher on coding benchmarks: 43.5 versus 37.6 in the Noometry coding category.
Which has the bigger context window?
Claude Sonnet 4 does, with 200K tokens against 131K.
How many benchmarks do Claude Sonnet 4 and gpt-oss-20b share?
32 benchmarks have published results for both models. Claude Sonnet 4 has 58 scored results on Noometry and gpt-oss-20b has 34.