Model Comparison
GPT-5.1 Instant vs Kimi K3Which is better in 2026?
Kimi K3 significantly outperforms across most benchmarks. GPT-5.1 Instant is 1.7x cheaper per token.
Verdict: GPT-5.1 Instant vs Kimi K3 — which is better?
GPT-5.1 Instant (by OpenAI) and Kimi K3 (by Moonshot AI) are two of the AI models people compare most. Here is how they stack up on benchmarks, price and capabilities, and which one to pick in 2026.
GPT-5.1 Instant outperforms in 0 benchmarks, while Kimi K3 is better at 1 benchmark (GPQA). Kimi K3 significantly outperforms across most benchmarks.
On price, GPT-5.1 Instant is roughly 1.7x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
Kimi K3 also accepts a larger context window (1,048,576 input tokens), making it the stronger choice for long documents and large codebases.
Choose GPT-5.1 Instant if…
- cost matters — it's about 1.7x cheaper per token
Choose Kimi K3 if…
- you want the strongest raw capability — it leads on 1 of 1 shared benchmarks
- you process long inputs — it offers a 1,048,576 token context window
- you want the most recent training data — it shipped Jul 2026
Performance Benchmarks
Comparative analysis across standard metrics
GPT-5.1 Instant outperforms in 0 benchmarks, while Kimi K3 is better at 1 benchmark (GPQA).
Kimi K3 significantly outperforms across most benchmarks.
Arena Performance
Human preference votes
Pricing Analysis
Price comparison per million tokens
For input processing, GPT-5.1 Instant ($1.25/1M tokens) is 2.4x cheaper than Kimi K3 ($3.00/1M tokens).
For output processing, GPT-5.1 Instant ($10.00/1M tokens) is 1.5x cheaper than Kimi K3 ($15.00/1M tokens).
In conclusion, Kimi K3 is more expensive than GPT-5.1 Instant.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
Kimi K3 accepts 1,048,576 input tokens compared to GPT-5.1 Instant's 400,000 tokens. Kimi K3 can generate longer responses up to 1,048,576 tokens, while GPT-5.1 Instant is limited to 128,000 tokens.
Input Capabilities
Supported data types and modalities
Both GPT-5.1 Instant and Kimi K3 support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
GPT-5.1 Instant
Kimi K3
Release Timeline
When each model was launched
GPT-5.1 Instant was released on 2025-11-12, while Kimi K3 was released on 2026-07-16.
Kimi K3 is 8 months newer than GPT-5.1 Instant.
Nov 12, 2025
8 months ago
Jul 16, 2026
1 weeks ago
8mo newerKnowledge Cutoff
When training data ends
Neither model specifies a knowledge cutoff date.
Unable to compare the recency of their training data.
Provider Availability
GPT-5.1 Instant is available from OpenAI. Kimi K3 is available from Moonshot AI.
GPT-5.1 Instant
Kimi K3
Outputs Comparison
Key Takeaways
Kimi K3
View detailsMoonshot AI
Detailed Comparison
Interactive Arena
Judge for yourself.
Run your own prompts against GPT-5.1 Instant and Kimi K3 side-by-side, then vote on the output you prefer.
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FAQ
Common questions about GPT-5.1 Instant vs Kimi K3.