# Claude Opus 4.8 vs Kimi K3

> Claude Opus 4.8 is the stronger model overall, scoring 60.7 to 59.5 on the Noometry Index. Kimi K3 costs 1.7× less per token, which makes it the better buy when Claude Opus 4.8's lead doesn't matter for your workload.

- Canonical page: https://noometry.com/compare/claude-opus-4-8-vs-kimi-k3
- Last updated: 2026-10-10
- Shared benchmarks: 52

## Summary

- They share 52 benchmarks with published results for both. Claude Opus 4.8 scores higher in 4 categories and Kimi K3 in 6 categories; 7 gaps are clear of the uncertainty.
- The widest gap is in agentic & tool use, where Claude Opus 4.8 leads 47.6 to 41.8.
- The biggest single-benchmark swing is GBAEval: 70.9% for Claude Opus 4.8 and 48.3% for Kimi K3.
- Kimi K3 is cheaper at $3 / $15 per million input/output tokens, against $5 / $25 for Claude Opus 4.8.
- Kimi K3 accepts more context: 1.05M tokens versus 1M.
- Kimi K3 has downloadable open weights; the other is API-only.

## Snapshot

| | Claude Opus 4.8 | Kimi K3 |
|---|---|---|
| Provider | Anthropic | Moonshot AI |
| Noometry Index | 60.7 | 59.5 |
| Rank | 9 | 12 |
| Context | 1M | 1.05M |
| Input $/M | $5 | $3 |
| Output $/M | $25 | $15 |
| Weights | Proprietary | Open |

## Coding

- Claude Opus 4.8: 60.2 (#9)
- Kimi K3: 60.6 (#8)

| Benchmark | Claude Opus 4.8 | Kimi K3 |
|---|---|---|
| DeepSWE | 59% | 68.5% |
| FrontierCode | 46.5% | 44.2% |
| LMArena WebDev | 1556 | 1659 |
| SciCode | 53.5% | 59.5% |
| WeirdML | 82.9% | 82.6% |
| LMArena Coding | 1491 | 1509 |
| ALE-Bench | 1,564 | 1,524 |
| FrontierSWE | — | 25.9% |
| GSO | 47.1% | — |

## Agentic & Tool Use

- Claude Opus 4.8: 47.6 (#10)
- Kimi K3: 41.8 (#19)

| Benchmark | Claude Opus 4.8 | Kimi K3 |
|---|---|---|
| APEX-Agents | 48.9% | 50.6% |
| τ²-bench Banking | 39.7% | 37.1% |
| PostTrainBench | 33.8% | 32% |
| GBAEval | 70.9% | 48.3% |
| GDP.pdf | 24% | 19% |
| Vending-Bench 2 | 5,787 | 5,165 |
| OSWorld 2.0 | 20.6% | — |
| Remote Labor Index | 8.3% | — |
| DeepResearch Bench | 50.2% | — |
| LMArena Search | 1204 | — |

## Reasoning

- Claude Opus 4.8: 64.6 (#14)
- Kimi K3: 63.0 (#15)

| Benchmark | Claude Opus 4.8 | Kimi K3 |
|---|---|---|
| ARC-AGI-2 | 72.1% | 60.4% |
| SimpleBench | 64.8% | 60.7% |
| NYT Connections (extended) | 91.1% | 93.6% |
| ARC-AGI-1 | 92.5% | 94.5% |
| CritPt | 20.9% | 23.4% |
| Chess Puzzles | 34% | 39% |
| LMArena Hard Prompts | 1481 | 1495 |
| Mystery Game Puzzles | 36% | 26% |
| DTBench | 94.9% | 91.2% |
| LMCA | 57.5% | 52.7% |
| Surface Evolver Bench | 87.5% | 95% |
| Epoch Capabilities Index | 158.3 | 157.68 |
| ForecastBench | 59.9 | 61.1 |
| Kagi LLM Benchmark | 88.8% | — |
| EnigmaEval | 23.5% | — |
| EBR-Bench | 28.6% | — |
| Bench to the Future 3 | 0.14 | — |

## Math

- Claude Opus 4.8: 78.2 (#11)
- Kimi K3: 74.0 (#13)

| Benchmark | Claude Opus 4.8 | Kimi K3 |
|---|---|---|
| FrontierMath (Tiers 1-3) | 80% | 72.2% |
| FrontierMath Tier 4 | 56.1% | 39% |
| MathArena Final-Answer Competitions | 91.8% | 87.8% |
| OTIS Mock AIME 2024-2025 | 98.3% | 97.2% |
| ProofBench | 69% | 87% |
| LMArena Math | 1487 | 1493 |
| FrontierMath (Feb 2025 set) | 47.2% | — |
| FrontierMath Tier 4 (v1) | 31.3% | — |

## Knowledge

- Claude Opus 4.8: 61.3 (#26)
- Kimi K3: 63.2 (#19)

| Benchmark | Claude Opus 4.8 | Kimi K3 |
|---|---|---|
| GPQA Diamond | 91% | 93.1% |
| SimpleQA Verified | 53% | 50.6% |
| LMArena Expert | 1501 | 1520 |

## Multimodal

- Claude Opus 4.8: 43.2 (#20)
- Kimi K3: 38.4 (#58)

| Benchmark | Claude Opus 4.8 | Kimi K3 |
|---|---|---|
| Blueprint-Bench 2 | 14.5% | 29.5% |
| Furniture Assembly | 42.5% | 34.2% |
| LMArena Vision | 1295 | — |
| LMArena Document | 1475 | — |

## Multilingual

- Claude Opus 4.8: 55.4 (#31)
- Kimi K3: 56.5 (#20)

| Benchmark | Claude Opus 4.8 | Kimi K3 |
|---|---|---|
| LMArena Non-English | 1450 | 1466 |
| LMArena Chinese | 1509 | 1528 |
| LMArena French | 1482 | 1488 |
| LMArena German | 1470 | 1474 |
| LMArena Japanese | 1440 | 1492 |
| LMArena Korean | 1432 | 1465 |
| LMArena Russian | 1476 | 1481 |
| LMArena Spanish | 1470 | 1478 |

## Instruction Following

- Claude Opus 4.8: 77.6 (#22)
- Kimi K3: 77.8 (#13)

| Benchmark | Claude Opus 4.8 | Kimi K3 |
|---|---|---|
| LMArena Instruction Following | 1476 | 1481 |

## Long Context

- Claude Opus 4.8: 45.4 (#37)
- Kimi K3: 45.8 (#27)

| Benchmark | Claude Opus 4.8 | Kimi K3 |
|---|---|---|
| LMArena Longer Query | 1482 | 1494 |

## Writing & Preference

- Claude Opus 4.8: 72.1 (#17)
- Kimi K3: 76.7 (#4)

| Benchmark | Claude Opus 4.8 | Kimi K3 |
|---|---|---|
| LMArena Text | 1460 | 1476 |
| LMArena Creative Writing | 1453 | 1452 |
| EQ-Bench Creative Writing | 1840 | 2082 |
| EQ-Bench 4 | 1281 | 1339 |
| LMArena Multi-Turn | 1476 | 1488 |

## FAQ

### Is Claude Opus 4.8 better than Kimi K3?

Claude Opus 4.8 is the stronger model overall, scoring 60.7 to 59.5 on the Noometry Index. Kimi K3 costs 1.7× less per token, which makes it the better buy when Claude Opus 4.8's lead doesn't matter for your workload.

### Which is cheaper, Claude Opus 4.8 or Kimi K3?

Kimi K3 is cheaper. It lists at $3 per million input tokens and $15 per million output tokens; Claude Opus 4.8 lists at $5 and $25.

### Is Claude Opus 4.8 or Kimi K3 better for coding?

They score almost the same on coding (60.2 vs 60.6); test both on your own repository before choosing.

### Which has the bigger context window?

Kimi K3 does, with 1.05M tokens against 1M.

### How many benchmarks do Claude Opus 4.8 and Kimi K3 share?

52 benchmarks have published results for both models. Claude Opus 4.8 has 65 scored results on Noometry and Kimi K3 has 53.