Kimi K2.5vsGrok Code Fast 1
Kimi K2.5 | Grok Code Fast 1 | |
|---|---|---|
| Specifications | ||
ParametersA rough measure of how big the model is. More parameters usually means more capable and more expensive to run, though it is a poor guide on its own — a smaller, newer model often beats a larger, older one. | 1T | — |
Context windowHow much text the model can hold in mind at once — your question, any documents you attach, the conversation so far, and its own reply. Go past it and the earliest part falls out of view. | 256k | — |
| API pricingUSD per 1M tokens · lower wins · base tier | ||
Input priceWhat you pay for everything you send the model — your question, plus any documents or earlier conversation you include with it. | $0.60 | $1.00 |
Output priceWhat you pay for the text the model writes back. It is normally the dearer half: producing an answer costs more than reading one. | $3.00 | $2.00 |
Cached input priceA reduced rate for text you send over and over. If every request starts with the same instructions or the same document, the provider keeps a copy ready and charges less to read it again. | $0.10 | $0.20 |
| Benchmarks | ||
Arena Elo (Code)Community preference (code) — Like the text arena, but people vote on which AI writes better code. The votes become a chess-style Elo rating on arena.ai. Higher is better. | 1433 | 1163 |
| BenchmarksPublished by one model only | ||
BullshitBench v2Nonsense detection — Given a confidently-worded but nonsensical prompt, does the AI spot that it makes no sense and push back — instead of playing along and inventing an answer? The score is how often it clearly called out the nonsense. Higher is better. | 52% | — |
SWE-Bench VerifiedCoding — Real coding tasks pulled from open-source projects — the AI has to find and fix actual bugs. A human-checked version of the original SWE-Bench. Higher is better. | 76.8% | — |
CursorBench v3.1Agentic coding — Cursor's own test of harder, real-world coding tasks inside a code editor. Higher is better. | 31.9% | — |
Next.js EvalsNext.js coding — Vercel's open eval of how well AI coding agents build and migrate real Next.js apps — measured as the share of tasks the agent completes successfully. Higher is better. | 21% | — |
LiveCodeBenchCompetitive coding — Coding problems published so recently the AI can't have seen them in training — a contamination-free test of raw programming skill. Higher is better. | 85% | — |
GPQA DiamondScience — Graduate-level science questions in biology, physics, and chemistry — hard enough that subject-matter PhDs score around 65%. Higher is better. | 87.6% | — |
| Overview | ||
| Company | Moonshot AI | SpaceXAI |
| Release date | Jan 27 2026 | Aug 28 2025 |
| Access | Open Weight | Proprietary |
Frequently asked questions
Kimi K2.5 leads Grok Code Fast 1 on 1 of the 1 benchmark they both report (Arena Elo (Code)). Kimi K2.5 is cheaper on input: $0.60 vs $1.00 per million tokens. Grok Code Fast 1 is cheaper on output: $2.00 vs $3.00 per million tokens. Figures are base-tier rates. Grok Code Fast 1 shipped 152 days before Kimi K2.5, so benchmark comparisons should account for the intervening progress.
Kimi K2.5 is open weight, while Grok Code Fast 1 is proprietary.
On Arena Elo (Code), Kimi K2.5 leads at 1433 vs Grok Code Fast 1 at 1163.
Kimi K2.5 was released by Moonshot AI on Jan 27 2026.
Grok Code Fast 1 was released by SpaceXAI on Aug 28 2025.
Kimi K2.5 is cheaper on input: $0.60 vs $1.00 per million tokens. Grok Code Fast 1 is cheaper on output: $2.00 vs $3.00 per million tokens. Figures are base-tier rates. Rates are pay-as-you-go API prices verified on August 18, 2026.
Kimi K2.5 is an open weight model released by Moonshot AI. Grok Code Fast 1 is a proprietary model released by SpaceXAI.