# Kimi K2.5 Instant vs Step 3.5 Flash

> Kimi K2.5 Instant is the stronger model overall, scoring 42.9 to 41.7 on the Noometry Index.

- Canonical page: https://noometry.com/compare/kimi-k2-5-instant-vs-step-3-5-flash
- Last updated: 2026-10-10
- Shared benchmarks: 16

## Summary

- They share 16 benchmarks with published results for both. Kimi K2.5 Instant scores higher in 7 categories and Step 3.5 Flash in 1 category; 6 gaps are clear of the uncertainty.
- The widest gap is in reasoning, where Kimi K2.5 Instant leads 28.5 to 21.2.

## Snapshot

| | Kimi K2.5 Instant | Step 3.5 Flash |
|---|---|---|
| Provider | Moonshot AI | StepFun |
| Noometry Index | 42.9 | 41.7 |
| Rank | 92 | 116 |
| Context | — | 256K |
| Input $/M | — | $0.10 |
| Output $/M | — | $0.30 |
| Weights | Open | Open |

## Coding

- Kimi K2.5 Instant: 42.3 (#95)
- Step 3.5 Flash: 41.7 (#106)

| Benchmark | Kimi K2.5 Instant | Step 3.5 Flash |
|---|---|---|
| LMArena Coding | 1483 | 1436 |
| LMArena WebDev | 1404 | — |

## Reasoning

- Kimi K2.5 Instant: 28.5 (#88)
- Step 3.5 Flash: 21.2 (#202)

| Benchmark | Kimi K2.5 Instant | Step 3.5 Flash |
|---|---|---|
| LMArena Hard Prompts | 1443 | 1411 |
| NYT Connections (extended) | — | 28.4% |

## Math

- Kimi K2.5 Instant: 36.6 (#105)
- Step 3.5 Flash: 40.6 (#77)

| Benchmark | Kimi K2.5 Instant | Step 3.5 Flash |
|---|---|---|
| LMArena Math | 1443 | 1408 |
| MathArena Final-Answer Competitions | — | 66.8% |

## Knowledge

- Kimi K2.5 Instant: 39.5 (#121)
- Step 3.5 Flash: 39.0 (#127)

| Benchmark | Kimi K2.5 Instant | Step 3.5 Flash |
|---|---|---|
| LMArena Expert | 1438 | 1422 |

## Multimodal

- Kimi K2.5 Instant: 39.5 (#47)
- Step 3.5 Flash: —

| Benchmark | Kimi K2.5 Instant | Step 3.5 Flash |
|---|---|---|
| LMArena Vision | 1254 | — |

## Multilingual

- Kimi K2.5 Instant: 52.2 (#89)
- Step 3.5 Flash: 50.7 (#115)

| Benchmark | Kimi K2.5 Instant | Step 3.5 Flash |
|---|---|---|
| LMArena Non-English | 1406 | 1386 |
| LMArena Chinese | 1450 | 1448 |
| LMArena French | 1403 | 1421 |
| LMArena German | 1413 | 1404 |
| LMArena Korean | 1378 | 1350 |
| LMArena Russian | 1404 | 1385 |
| LMArena Spanish | 1448 | 1419 |
| LMArena Japanese | — | 1353 |

## Instruction Following

- Kimi K2.5 Instant: 75.5 (#61)
- Step 3.5 Flash: 73.3 (#119)

| Benchmark | Kimi K2.5 Instant | Step 3.5 Flash |
|---|---|---|
| LMArena Instruction Following | 1430 | 1385 |

## Long Context

- Kimi K2.5 Instant: 43.8 (#82)
- Step 3.5 Flash: 42.8 (#112)

| Benchmark | Kimi K2.5 Instant | Step 3.5 Flash |
|---|---|---|
| LMArena Longer Query | 1435 | 1402 |

## Writing & Preference

- Kimi K2.5 Instant: 60.8 (#91)
- Step 3.5 Flash: 59.0 (#108)

| Benchmark | Kimi K2.5 Instant | Step 3.5 Flash |
|---|---|---|
| LMArena Text | 1420 | 1403 |
| LMArena Creative Writing | 1379 | 1357 |
| LMArena Multi-Turn | 1427 | 1405 |

## FAQ

### Is Kimi K2.5 Instant better than Step 3.5 Flash?

Kimi K2.5 Instant is the stronger model overall, scoring 42.9 to 41.7 on the Noometry Index.

### Is Kimi K2.5 Instant or Step 3.5 Flash better for coding?

They score almost the same on coding (42.3 vs 41.7); test both on your own repository before choosing.

### How many benchmarks do Kimi K2.5 Instant and Step 3.5 Flash share?

16 benchmarks have published results for both models. Kimi K2.5 Instant has 18 scored results on Noometry and Step 3.5 Flash has 19.