Kimi K3 vs Kimi K2: Full Comparison (2026)

Kimi K3 isn’t an incremental update to Kimi K2 — Moonshot AI calls it a new generation, and the numbers back that up. Here’s the complete side-by-side comparison, plus honest guidance on when K2 might still make sense. New to K3? Start with the complete Kimi K3 guide.

Spec-by-spec comparison

Spec	Kimi K2	Kimi K3
Total parameters	1.0T	2.8T
Architecture	MLA MoE	KDA + Attention Residuals + Stable LatentMoE
Experts	384	896 (16 active / token)
Context window	256K tokens	1,048,576 tokens (1M)
Vision / video input	—	Native
Long-context decode	baseline	Up to 6.3× faster
Scaling efficiency	baseline	~2.5× better
Frontend Code Arena	#18 (K2.6)	#1
Weights license	Modified MIT	Modified MIT (July 27)

The five differences that actually matter

1. Context window: 256K → 1M tokens

This is the headline upgrade. K2’s 256K window was already generous; K3’s 1,048,576 tokens means entire codebases, full-length books, or hours of transcripts in a single prompt — with no chunking or retrieval hacks.

2. Speed at long context: up to 6.3× faster

A big context window is useless if responses crawl. K2’s attention slowed sharply as prompts grew. K3’s Kimi Delta Attention (KDA) keeps decoding fast even at hundreds of thousands of tokens — up to 6.3× faster than K2 at long contexts. In practice: K3’s 1M window is one you’ll actually use.

3. Intelligence: 2.8T params with 896 experts

K3 nearly triples total parameters and more than doubles the expert count (384 → 896), while keeping just 16 experts active per token. Combined with ~2.5× better scaling efficiency from Attention Residuals, the capability jump is larger than the parameter jump suggests. On Artificial Analysis’s independent ranking, K3 sits at #4 of 189 models — far above anything K2 achieved.

4. Native vision and video

K2 was text-only. K3 understands images and video natively, which powers its agentic wins — like the #1 BrowseComp score (91.2) — and enables use cases (UI analysis, video Q&A, visual debugging) that simply weren’t possible on K2.

5. Coding: #18 → #1

On the Frontend Code Arena, K2.6 ranked #18. K3 ranks #1. It’s also #1 on Program Bench (77.8) and SWE Marathon (42.0), beating GPT-5.6 Sol and Claude Opus 4.8 on the latter. If you write code with AI, this alone justifies the switch.

Benchmarks: K3 vs the frontier (context K2 never reached)

Benchmark	Kimi K3	Note
Program Bench	77.8 (#1)	Edges GPT-5.6 Sol (77.6)
SWE Marathon	42.0 (#1)	Beats Claude Opus 4.8 (40.0)
BrowseComp	91.2 (#1)	Beats GPT-5.6 Sol (90.4)
Terminal-Bench 2.1	88.3 (#2)	0.5 behind GPT-5.6 Sol
Artificial Analysis	#4 / 189	Best open-weight result ever

Pricing

K3’s API pricing ($0.30 cache-hit / $3.00 cache-miss input, $15.00 output per 1M tokens) works out to $0.94 per average benchmark task — roughly half the per-task cost of Claude Opus 4.8 or GPT-5.5. Both K2 and K3 remain free to chat with in the Kimi app.

Should you switch to K3?

Switch to K3 if:

• You work with long documents or large codebases (the 1M window + 6.3× speed is transformative)
• You code with AI — #1 Frontend Code Arena, #1 SWE Marathon
• You need image or video understanding
• You want the best open-weight model, period

K2 might still make sense if:

• You’re self-hosting on limited hardware — K2’s 1.0T weights are far easier to run than K3’s 2.8T
• You have fine-tunes or pipelines built on K2 and its 256K context covers your workload
• Your tasks are short-context and cost-sensitive at scale

FAQ

Is Kimi K3 better than Kimi K2? Yes, across the board — 2.8T vs 1.0T parameters, 1M vs 256K context, native vision, up to 6.3× faster long-context decoding, and #18 → #1 on the Frontend Code Arena.

Should I upgrade from Kimi K2 to K3? Almost certainly — K3 is free in the same app and beats K2 everywhere. The main reason to stay on K2 is self-hosting with limited hardware.

Is Kimi K3 more expensive than K2? No — both are free in the Kimi app. K3’s API costs roughly half per task versus comparable frontier models.

Does K3 support images and video like K2? K2 was text-only. K3 adds native image and video understanding for the first time.

The verdict

For almost everyone, Kimi K3 is simply the better model — bigger, faster where it counts, multimodal, and the first open-weight model to genuinely pressure the closed frontier. K2 remains relevant mainly for self-hosters constrained by hardware.

Ready to try it? K3 is free in the Kimi app — and signing up through an invite link gets you bonus membership credits. For setup options, see how to download Kimi K3 on PC or the full specifications breakdown.