Model Comparison
GPT-5.5 Instant vs Kimi K3Which is better in 2026?
Kimi K3 significantly outperforms across most benchmarks. Kimi K3 is 1.9x cheaper per token.
Verdict: GPT-5.5 Instant vs Kimi K3 — which is better?
GPT-5.5 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-5.5 Instant outperforms in 0 benchmarks, while Kimi K3 is better at 3 benchmarks (CharXiv-R, GPQA, MMMU-Pro). Kimi K3 significantly outperforms across most benchmarks.
On price, Kimi K3 is roughly 1.9x 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-5.5 Instant if…
- you want predictable pricing at $5.00/M input and $30.00/M output
Choose Kimi K3 if…
- you want the strongest raw capability — it leads on 3 of 3 shared benchmarks
- cost matters — it's about 1.9x cheaper per token
- 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-5.5 Instant outperforms in 0 benchmarks, while Kimi K3 is better at 3 benchmarks (CharXiv-R, GPQA, MMMU-Pro).
Kimi K3 significantly outperforms across most benchmarks.
Arena Performance
Human preference votes
Pricing Analysis
Price comparison per million tokens
For input processing, GPT-5.5 Instant ($5.00/1M tokens) is 1.7x more expensive than Kimi K3 ($3.00/1M tokens).
For output processing, GPT-5.5 Instant ($30.00/1M tokens) is 2.0x more expensive than Kimi K3 ($15.00/1M tokens).
In conclusion, GPT-5.5 Instant is more expensive than Kimi K3.*
* 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-5.5 Instant's 400,000 tokens. Kimi K3 can generate longer responses up to 1,048,576 tokens, while GPT-5.5 Instant is limited to 128,000 tokens.
Input Capabilities
Supported data types and modalities
Both GPT-5.5 Instant and Kimi K3 support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
GPT-5.5 Instant
Kimi K3
Release Timeline
When each model was launched
GPT-5.5 Instant was released on 2026-05-05, while Kimi K3 was released on 2026-07-16.
Kimi K3 is 2 months newer than GPT-5.5 Instant.
May 5, 2026
2 months ago
Jul 16, 2026
4 days ago
2mo newerKnowledge Cutoff
When training data ends
GPT-5.5 Instant has a documented knowledge cutoff of 2025-08-31, while Kimi K3's cutoff date is not specified.
We can confirm GPT-5.5 Instant's training data extends to 2025-08-31, but cannot make a direct comparison without Kimi K3's cutoff date.
Aug 2025
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Provider Availability
GPT-5.5 Instant is available from OpenAI. Kimi K3 is available from Moonshot AI.
GPT-5.5 Instant
Kimi K3
Outputs Comparison
Key Takeaways
No standout differentiators in the data we have for this pair.
Kimi K3
View detailsMoonshot AI
Detailed Comparison
Interactive Arena
Judge for yourself.
Run your own prompts against GPT-5.5 Instant and Kimi K3 side-by-side, then vote on the output you prefer.
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FAQ
Common questions about GPT-5.5 Instant vs Kimi K3.