Model comparison
GPT-5.3 Chat vs Kimi K2.5
Kimi K2.5 is the stronger model overall, scoring 47.8 to 42.1 on the Noometry Index.
Last verified . 18 shared benchmarks.
Summary
- They share 18 benchmarks with published results for both. GPT-5.3 Chat scores higher in 0 categories and Kimi K2.5 in 8 categories; 8 gaps are clear of the uncertainty.
- The widest gap is in knowledge, where Kimi K2.5 leads 53.6 to 38.2.
- Kimi K2.5 is cheaper at $0.45 / $2.25 per million input/output tokens, against $1.75 / $14 for GPT-5.3 Chat.
- Kimi K2.5 accepts more context: 262K tokens versus 128K.
- Kimi K2.5 has downloadable open weights; the other is API-only.
Side by side
| GPT-5.3 Chat | Kimi K2.5 | |
|---|---|---|
| Provider | OpenAI | Moonshot AI |
| Noometry Index | 42.1 | 47.8 |
| Released | 2026-03-03 | 2026-01-27 |
| Weights | Proprietary | Open |
| Context window | 128K | 262K |
| Max output | 16K | 262K |
| Input $ / M tokens | $1.75 | $0.45 |
| Output $ / M tokens | $14 | $2.25 |
| Results tracked | 18 | 51 |
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Category by category
Coding Kimi K2.5 leads
GPT-5.3 Chat: 40.8 (#124), Kimi K2.5: 48.7 (#48)
| Benchmark | GPT-5.3 Chat | Kimi K2.5 |
|---|---|---|
| LMArena Coding | 1408 | 1474 |
| SWE-bench Verified | — | 73.8% |
| SWE-bench Verified (bash only) | — | 70.8% |
| LMArena WebDev | — | 1436 |
| SWE-bench Multilingual | — | 67.3% |
| SciCode | — | 49% |
| WeirdML | — | 45.6% |
| ALE-Bench | — | 821.65 |
Agentic & Tool Use Not comparable
GPT-5.3 Chat: —, Kimi K2.5: 34.0 (#44)
| Benchmark | GPT-5.3 Chat | Kimi K2.5 |
|---|---|---|
| Terminal-Bench | — | 43.2% |
| OSWorld | — | 63.3% |
| Vending-Bench 2 | — | 1,198 |
Reasoning Kimi K2.5 leads
GPT-5.3 Chat: 27.3 (#105), Kimi K2.5: 31.2 (#74)
| Benchmark | GPT-5.3 Chat | Kimi K2.5 |
|---|---|---|
| LMArena Hard Prompts | 1399 | 1454 |
| ARC-AGI-2 | — | 11.8% |
| SimpleBench | — | 46.8% |
| Kagi LLM Benchmark | — | 78.5% |
| NYT Connections (extended) | — | 69.9% |
| ARC-AGI-1 | — | 65.3% |
| CritPt | — | 3.1% |
| Chess Puzzles | — | 12% |
| EnigmaEval | — | 3.4% |
| Thematic Generalization | — | 69.4% |
| Epoch Capabilities Index | — | 148.05 |
Math Kimi K2.5 leads
GPT-5.3 Chat: 35.4 (#146), Kimi K2.5: 50.3 (#46)
| Benchmark | GPT-5.3 Chat | Kimi K2.5 |
|---|---|---|
| LMArena Math | 1389 | 1470 |
| MathArena Final-Answer Competitions | — | 62.3% |
| OTIS Mock AIME 2024-2025 | — | 92.2% |
| FrontierMath (Feb 2025 set) | — | 27.9% |
| FrontierMath Tier 4 (v1) | — | 4.2% |
Knowledge Kimi K2.5 leads
GPT-5.3 Chat: 38.2 (#137), Kimi K2.5: 53.6 (#52)
| Benchmark | GPT-5.3 Chat | Kimi K2.5 |
|---|---|---|
| LMArena Expert | 1397 | 1466 |
| GPQA Diamond | — | 87.6% |
| Humanity's Last Exam | — | 24.4% |
| SimpleQA Verified | — | 34.3% |
| Vectara Hallucination Rate | — | 14.2% |
Multimodal Not comparable
GPT-5.3 Chat: —, Kimi K2.5: 40.4 (#37)
| Benchmark | GPT-5.3 Chat | Kimi K2.5 |
|---|---|---|
| LMArena Vision | — | 1269 |
| LMArena Document | — | 1430 |
Multilingual Kimi K2.5 leads
GPT-5.3 Chat: 50.5 (#119), Kimi K2.5: 54.1 (#50)
| Benchmark | GPT-5.3 Chat | Kimi K2.5 |
|---|---|---|
| LMArena Non-English | 1383 | 1433 |
| LMArena Chinese | 1433 | 1495 |
| LMArena French | 1398 | 1454 |
| LMArena German | 1384 | 1441 |
| LMArena Japanese | 1351 | 1422 |
| LMArena Korean | 1347 | 1412 |
| LMArena Russian | 1400 | 1436 |
| LMArena Spanish | 1371 | 1450 |
Instruction Following Kimi K2.5 leads
GPT-5.3 Chat: 73.0 (#124), Kimi K2.5: 75.5 (#60)
| Benchmark | GPT-5.3 Chat | Kimi K2.5 |
|---|---|---|
| LMArena Instruction Following | 1378 | 1431 |
Long Context Kimi K2.5 leads
GPT-5.3 Chat: 42.6 (#115), Kimi K2.5: 52.1 (#7)
| Benchmark | GPT-5.3 Chat | Kimi K2.5 |
|---|---|---|
| LMArena Longer Query | 1396 | 1445 |
| Fiction.LiveBench | — | 86.1% |
| CL-bench | — | 19.3% |
| CL-bench Life | — | 13.2% |
Writing & Preference Kimi K2.5 leads
GPT-5.3 Chat: 63.3 (#65), Kimi K2.5: 65.3 (#51)
| Benchmark | GPT-5.3 Chat | Kimi K2.5 |
|---|---|---|
| LMArena Text | 1389 | 1445 |
| LMArena Creative Writing | 1356 | 1423 |
| EQ-Bench Creative Writing | 1690 | 1579 |
| LMArena Multi-Turn | 1413 | 1444 |
Frequently asked questions
Is GPT-5.3 Chat better than Kimi K2.5?
Kimi K2.5 is the stronger model overall, scoring 47.8 to 42.1 on the Noometry Index.
Which is cheaper, GPT-5.3 Chat or Kimi K2.5?
Kimi K2.5 is cheaper. It lists at $0.45 per million input tokens and $2.25 per million output tokens; GPT-5.3 Chat lists at $1.75 and $14.
Is GPT-5.3 Chat or Kimi K2.5 better for coding?
Kimi K2.5 scores higher on coding benchmarks: 48.7 versus 40.8 in the Noometry coding category.
Which has the bigger context window?
Kimi K2.5 does, with 262K tokens against 128K.
How many benchmarks do GPT-5.3 Chat and Kimi K2.5 share?
18 benchmarks have published results for both models. GPT-5.3 Chat has 18 scored results on Noometry and Kimi K2.5 has 51.