Model comparison
gpt-oss-20b vs Kimi K2 (Jul 2025)
Kimi K2 (Jul 2025) is the stronger model overall, scoring 41.2 to 32.5 on the Noometry Index. gpt-oss-20b costs 28× less per token, which makes it the better buy when Kimi K2 (Jul 2025)'s lead doesn't matter for your workload.
Last verified . 27 shared benchmarks.
Summary
- They share 27 benchmarks with published results for both. gpt-oss-20b scores higher in 0 categories and Kimi K2 (Jul 2025) in 9 categories; 9 gaps are clear of the uncertainty.
- The widest gap is in writing & preference, where Kimi K2 (Jul 2025) leads 62.3 to 35.5.
- The biggest single-benchmark swing is Terminal-Bench: 3.4% for gpt-oss-20b and 35.7% for Kimi K2 (Jul 2025).
- gpt-oss-20b is cheaper at $0.018 / $0.09 per million input/output tokens, against $0.57 / $2.30 for Kimi K2 (Jul 2025).
- Kimi K2 (Jul 2025) accepts more context: 262K tokens versus 131K.
Side by side
| gpt-oss-20b | Kimi K2 (Jul 2025) | |
|---|---|---|
| Provider | OpenAI | Moonshot AI |
| Noometry Index | 32.5 | 41.2 |
| Released | 2025-08-05 | 2025-07-12 |
| Weights | Open | Open |
| Context window | 131K | 262K |
| Max output | 16K | 262K |
| Input $ / M tokens | $0.018 | $0.57 |
| Output $ / M tokens | $0.09 | $2.30 |
| Results tracked | 34 | 42 |
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Category by category
Coding Kimi K2 (Jul 2025) leads
gpt-oss-20b: 37.6 (#192), Kimi K2 (Jul 2025): 42.4 (#102)
| Benchmark | gpt-oss-20b | Kimi K2 (Jul 2025) |
|---|---|---|
| WeirdML | 40.9% | 42.8% |
| LMArena Coding | 1306 | 1399 |
| ALE-Bench | 566.05 | 597.5 |
| SWE-bench Verified (bash only) | — | 63.4% |
| Aider Polyglot | — | 59.1% |
| SciCode | 34.4% | — |
| GSO | — | 4.9% |
Agentic & Tool Use Kimi K2 (Jul 2025) leads
gpt-oss-20b: 9.3 (#154), Kimi K2 (Jul 2025): 32.4 (#64)
| Benchmark | gpt-oss-20b | Kimi K2 (Jul 2025) |
|---|---|---|
| Terminal-Bench | 3.4% | 35.7% |
| Berkeley Function Calling Leaderboard | — | 59.1% |
| METR Time Horizons | — | 59.2% |
Reasoning Kimi K2 (Jul 2025) leads
gpt-oss-20b: 19.3 (#261), Kimi K2 (Jul 2025): 23.3 (#179)
| Benchmark | gpt-oss-20b | Kimi K2 (Jul 2025) |
|---|---|---|
| Kagi LLM Benchmark | 53.2% | 64.4% |
| LMArena Hard Prompts | 1274 | 1384 |
| Epoch Capabilities Index | 137.82 | 146.01 |
| SimpleBench | — | 26.3% |
| CritPt | 1.4% | — |
| Chess Puzzles | 4% | — |
| DTBench | 68% | — |
| LMCA | 14.5% | — |
| ForecastBench | — | 60.2 |
Math Kimi K2 (Jul 2025) leads
gpt-oss-20b: 39.4 (#103), Kimi K2 (Jul 2025): 42.7 (#83)
| Benchmark | gpt-oss-20b | Kimi K2 (Jul 2025) |
|---|---|---|
| Omni-MATH | 56.5% | 65.4% |
| LMArena Math | 1317 | 1397 |
| OTIS Mock AIME 2024-2025 | 65.3% | — |
| FrontierMath (Feb 2025 set) | — | 21.4% |
| FrontierMath Tier 4 (v1) | — | 0% |
Knowledge Kimi K2 (Jul 2025) leads
gpt-oss-20b: 34.6 (#195), Kimi K2 (Jul 2025): 37.3 (#157)
| Benchmark | gpt-oss-20b | Kimi K2 (Jul 2025) |
|---|---|---|
| MMLU-Pro | 74% | 81.9% |
| GPQA (HELM) | 59.4% | 65.3% |
| LMArena Expert | 1258 | 1365 |
| GPQA Diamond | 60.8% | — |
| Confabulations | — | 20.4% |
| Vectara Hallucination Rate | — | 17.9% |
Multilingual Kimi K2 (Jul 2025) leads
gpt-oss-20b: 42.2 (#197), Kimi K2 (Jul 2025): 49.6 (#130)
| Benchmark | gpt-oss-20b | Kimi K2 (Jul 2025) |
|---|---|---|
| LMArena Non-English | 1268 | 1372 |
| LMArena Chinese | 1314 | 1415 |
| LMArena German | 1255 | 1387 |
| LMArena Japanese | 1244 | 1349 |
| LMArena Korean | 1236 | 1325 |
| LMArena Russian | 1278 | 1385 |
| LMArena Spanish | 1267 | 1386 |
| LMArena French | — | 1379 |
Instruction Following Kimi K2 (Jul 2025) leads
gpt-oss-20b: 61.8 (#240), Kimi K2 (Jul 2025): 71.1 (#156)
| Benchmark | gpt-oss-20b | Kimi K2 (Jul 2025) |
|---|---|---|
| IFEval | 73.2% | 85% |
| LMArena Instruction Following | 1236 | 1348 |
Long Context Kimi K2 (Jul 2025) leads
gpt-oss-20b: 37.9 (#209), Kimi K2 (Jul 2025): 41.2 (#145)
| Benchmark | gpt-oss-20b | Kimi K2 (Jul 2025) |
|---|---|---|
| LMArena Longer Query | 1250 | 1353 |
| Fiction.LiveBench | — | 66.7% |
| CL-bench | — | 17.6% |
Writing & Preference Kimi K2 (Jul 2025) leads
gpt-oss-20b: 35.5 (#265), Kimi K2 (Jul 2025): 62.3 (#78)
| Benchmark | gpt-oss-20b | Kimi K2 (Jul 2025) |
|---|---|---|
| LMArena Text | 1287 | 1380 |
| LMArena Creative Writing | 1201 | 1350 |
| EQ-Bench Creative Writing | 666 | 1666 |
| WildBench | 73.7% | 86.2% |
| LMArena Multi-Turn | 1268 | 1371 |
| Short-Story Creative Writing | — | 85.6% |
Frequently asked questions
Is gpt-oss-20b better than Kimi K2 (Jul 2025)?
Kimi K2 (Jul 2025) is the stronger model overall, scoring 41.2 to 32.5 on the Noometry Index. gpt-oss-20b costs 28× less per token, which makes it the better buy when Kimi K2 (Jul 2025)'s lead doesn't matter for your workload.
Which is cheaper, gpt-oss-20b or Kimi K2 (Jul 2025)?
gpt-oss-20b is cheaper. It lists at $0.018 per million input tokens and $0.09 per million output tokens; Kimi K2 (Jul 2025) lists at $0.57 and $2.30.
Is gpt-oss-20b or Kimi K2 (Jul 2025) better for coding?
Kimi K2 (Jul 2025) scores higher on coding benchmarks: 42.4 versus 37.6 in the Noometry coding category.
Which has the bigger context window?
Kimi K2 (Jul 2025) does, with 262K tokens against 131K.
How many benchmarks do gpt-oss-20b and Kimi K2 (Jul 2025) share?
27 benchmarks have published results for both models. gpt-oss-20b has 34 scored results on Noometry and Kimi K2 (Jul 2025) has 42.