Model comparison
Kimi K2.5 Instant vs Step 3.5 Flash
Kimi K2.5 Instant is the stronger model overall, scoring 43.6 to 42.3 on the Noometry Index.
Last verified . 16 shared benchmarks.
StepFunSummary
- 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 29.7 to 22.2.
Side by side
| Kimi K2.5 Instant | Step 3.5 Flash | |
|---|---|---|
| Provider | Moonshot AI | StepFun |
| Noometry Index | 43.6 | 42.3 |
| Released | — | 2026-01-29 |
| Weights | Open | Open |
| Context window | — | 256K |
| Max output | — | 256K |
| Input $ / M tokens | — | $0.10 |
| Output $ / M tokens | — | $0.30 |
| Results tracked | 18 | 19 |
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Category by category
Coding Too close to call
Kimi K2.5 Instant: 42.6 (#97), Step 3.5 Flash: 42.4 (#105)
| Benchmark | Kimi K2.5 Instant | Step 3.5 Flash |
|---|---|---|
| LMArena Coding | 1484 | 1436 |
| LMArena WebDev | 1404 | — |
Reasoning Kimi K2.5 Instant leads
Kimi K2.5 Instant: 29.7 (#90), Step 3.5 Flash: 22.2 (#202)
| Benchmark | Kimi K2.5 Instant | Step 3.5 Flash |
|---|---|---|
| LMArena Hard Prompts | 1443 | 1411 |
| NYT Connections (extended) | — | 28.4% |
Math Step 3.5 Flash leads
Kimi K2.5 Instant: 39.4 (#105), Step 3.5 Flash: 42.6 (#84)
| Benchmark | Kimi K2.5 Instant | Step 3.5 Flash |
|---|---|---|
| LMArena Math | 1442 | 1408 |
| MathArena Final-Answer Competitions | — | 66.8% |
Knowledge Too close to call
Kimi K2.5 Instant: 40.2 (#123), Step 3.5 Flash: 39.6 (#132)
| Benchmark | Kimi K2.5 Instant | Step 3.5 Flash |
|---|---|---|
| LMArena Expert | 1440 | 1421 |
Multimodal Not comparable
Kimi K2.5 Instant: 40.2 (#50), Step 3.5 Flash: —
| Benchmark | Kimi K2.5 Instant | Step 3.5 Flash |
|---|---|---|
| LMArena Vision | 1254 | — |
Multilingual Kimi K2.5 Instant leads
Kimi K2.5 Instant: 52.0 (#94), Step 3.5 Flash: 50.5 (#119)
| Benchmark | Kimi K2.5 Instant | Step 3.5 Flash |
|---|---|---|
| LMArena Non-English | 1406 | 1385 |
| LMArena Chinese | 1449 | 1447 |
| LMArena French | 1403 | 1421 |
| LMArena German | 1413 | 1405 |
| LMArena Korean | 1378 | 1352 |
| LMArena Russian | 1404 | 1385 |
| LMArena Spanish | 1447 | 1419 |
| LMArena Japanese | — | 1354 |
Instruction Following Kimi K2.5 Instant leads
Kimi K2.5 Instant: 75.3 (#65), Step 3.5 Flash: 73.1 (#124)
| Benchmark | Kimi K2.5 Instant | Step 3.5 Flash |
|---|---|---|
| LMArena Instruction Following | 1430 | 1385 |
Long Context Kimi K2.5 Instant leads
Kimi K2.5 Instant: 43.9 (#83), Step 3.5 Flash: 42.8 (#117)
| Benchmark | Kimi K2.5 Instant | Step 3.5 Flash |
|---|---|---|
| LMArena Longer Query | 1435 | 1402 |
Writing & Preference Kimi K2.5 Instant leads
Kimi K2.5 Instant: 60.6 (#95), Step 3.5 Flash: 58.8 (#113)
| Benchmark | Kimi K2.5 Instant | Step 3.5 Flash |
|---|---|---|
| LMArena Text | 1420 | 1403 |
| LMArena Creative Writing | 1381 | 1357 |
| LMArena Multi-Turn | 1427 | 1405 |
Frequently asked questions
Is Kimi K2.5 Instant better than Step 3.5 Flash?
Kimi K2.5 Instant is the stronger model overall, scoring 43.6 to 42.3 on the Noometry Index.
Is Kimi K2.5 Instant or Step 3.5 Flash better for coding?
They score almost the same on coding (42.6 vs 42.4); 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.