GPT-5.5 Instant vs Kimi K3.1 Pro
Kimi K3.1 Pro leads the LLM Stats Score 55.5 to 31.7. Kimi K3.1 Pro is 2.8x cheaper per token.
OpenAI · Moonshot AI · Updated for 2026
Which is better?
Kimi K3.1 Pro leads the overall LLM Stats Score 55.5 to 31.7, ranking #5 overall.
In the 3 individual benchmarks reported for both models, Kimi K3.1 Pro wins 3; this is a narrower head-to-head signal than the composite indexes.
On price, Kimi K3.1 Pro is roughly 2.8x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
Kimi K3.1 Pro also accepts a larger context window (1,048,576 input tokens), making it the stronger choice for long documents and large codebases.
Based on current LLM Stats indexes, shared benchmarks, pricing, and model metadata for 2026.
Choose GPT-5.5 Instant
- you want predictable pricing at $5.00/M input and $30.00/M output
Choose Kimi K3.1 Pro
- overall performance matters — it scores 55.5 and ranks #5 on LLM Stats
- your work emphasizes reasoning — it leads those capability indexes
- you value its reported benchmark strengths — it wins 3 of 3 exact shared results
- cost matters — it's about 2.8x 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 Oct 2026
At a glance
The differences that matter most.
Capability indexes
Additional strengths measured across groups of related public benchmarks
Individual benchmarks
9 reported for GPT-5.5 Instant · 30 for Kimi K3.1 Pro
GPT-5.5 Instant outperforms in 0 benchmarks, while Kimi K3.1 Pro is better at 3 benchmarks (CharXiv-R, GPQA, MMMU-Pro).
Kimi K3.1 Pro significantly outperforms across most benchmarks.
Human preference
Blind head-to-head votes and playground preference scores
Pricing Analysis
Price comparison per million tokens
For input processing, GPT-5.5 Instant ($5.00/1M tokens) is 2.5x more expensive than Kimi K3.1 Pro ($2.00/1M tokens).
For output processing, GPT-5.5 Instant ($30.00/1M tokens) is 3.0x more expensive than Kimi K3.1 Pro ($10.00/1M tokens).
In conclusion, GPT-5.5 Instant is more expensive than Kimi K3.1 Pro.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
Kimi K3.1 Pro accepts 1,048,576 input tokens compared to GPT-5.5 Instant's 400,000 tokens. Kimi K3.1 Pro can generate longer responses up to 1,048,576 tokens, while GPT-5.5 Instant is limited to 128,000 tokens.
Input capabilities
Documented input modalities across available providers
Both GPT-5.5 Instant and Kimi K3.1 Pro support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
GPT-5.5 Instant
Kimi K3.1 Pro
Release Timeline
When each model was launched
GPT-5.5 Instant was released on 2026-05-05, while Kimi K3.1 Pro was released on 2026-10-23.
Kimi K3.1 Pro is 6 months newer than GPT-5.5 Instant.
May 5, 2026
5 months ago
Oct 23, 2026
2 days ago
5mo newerKnowledge Cutoff
When training data ends
GPT-5.5 Instant has a documented knowledge cutoff of 2025-08-31, while Kimi K3.1 Pro'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 K3.1 Pro's cutoff date.
Aug 2025
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Provider Availability
GPT-5.5 Instant is available from OpenAI. Kimi K3.1 Pro is available from Moonshot AI.
GPT-5.5 Instant
Kimi K3.1 Pro
Outputs Comparison
Judge for yourself.
Run your own prompts against GPT-5.5 Instant and Kimi K3.1 Pro side-by-side, then vote on the output you prefer.
FAQ
Common questions about GPT-5.5 Instant vs Kimi K3.1 Pro.