What is the difference between GPT-5.1 and Kimi K2 Thinking?

GPT-5.1 is developed by OpenAI while Kimi K2 Thinking is developed by Moonshot AI. GPT-5.1 has a 400K token context window vs Kimi K2 Thinking's 262K. You can compare their actual outputs across 51 challenges on Rival to see how they differ in practice.

Which is better, GPT-5.1 or Kimi K2 Thinking?

It depends on your use case. GPT-5.1 and Kimi K2 Thinking each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 51 challenges so you can judge which fits your needs best.

How much does GPT-5.1 cost compared to Kimi K2 Thinking?

GPT-5.1 costs $1.25/M input tokens and Kimi K2 Thinking costs $0.6/M input tokens. Kimi K2 Thinking is $0.65/M cheaper per input. Check their side-by-side outputs on Rival to see if the price difference is justified by quality.

How can I compare GPT-5.1 and Kimi K2 Thinking on Rival?

This page shows a side-by-side comparison of GPT-5.1 and Kimi K2 Thinking across shared challenges. You can vote on which model produced the better output in a blind duel. Browsing and voting are free. No account is needed to look; signing in only saves your votes and likes.

What is the difference between GPT-5.1 and Kimi K2 Thinking?

GPT-5.1 is developed by OpenAI while Kimi K2 Thinking is developed by Moonshot AI. GPT-5.1 has a 400K token context window vs Kimi K2 Thinking's 262K. You can compare their actual outputs across 51 challenges on Rival to see how they differ in practice.

Which is better, GPT-5.1 or Kimi K2 Thinking?

It depends on your use case. GPT-5.1 and Kimi K2 Thinking each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 51 challenges so you can judge which fits your needs best.

How much does GPT-5.1 cost compared to Kimi K2 Thinking?

GPT-5.1 costs $1.25/M input tokens and Kimi K2 Thinking costs $0.6/M input tokens. Kimi K2 Thinking is $0.65/M cheaper per input. Check their side-by-side outputs on Rival to see if the price difference is justified by quality.

How can I compare GPT-5.1 and Kimi K2 Thinking on Rival?

This page shows a side-by-side comparison of GPT-5.1 and Kimi K2 Thinking across shared challenges. You can vote on which model produced the better output in a blind duel. Browsing and voting are free. No account is needed to look; signing in only saves your votes and likes.

GPT-5.1 vs Kimi K2 Thinking: Which Is Better?

Updated Nov 2025

Our Verdict

GPT-5.1

Kimi K2 ThinkingRunner-up

No community votes yet. On paper, GPT-5.1 has the edge — bigger context window, major provider backing.

Kimi K2 Thinking is 4.0x cheaper per token — worth considering if cost matters.

Too close to call

API pricing

Cost per 1M tokens

GPT-5.1

Input

$1.25

Output

$10.00

Kimi K2 Thinking

Input

$0.60

2.1× cheaper

Output

$2.50

4.0× cheaper

Kimi K2 Thinking is cheaper on both — 2.1× input, 4.0× output

Writing DNA

Style Comparison

Similarity

47%

Kimi K2 Thinking uses 2.1x more transitions

GPT-5.1

Kimi K2 Thinking

62%Vocabulary57%

19wSentence Length26w

0.29Hedging0.36

3.5Bold5.8

7.2Lists6.0

0.00Emoji0.00

0.61Headings0.56

0.03Transitions0.06

Based on 14 + 14 text responses

Research

What we learned reading every model

GPT-5.1 and Kimi K2 Thinking have opinions about your brand too.Ask 10 models what they tell people about you. Verbatim receipts.Run the mirror

FAQ

Common questions

Keep exploring

More comparisons

GPT-5.1 vs MiniMax M3New provider

GPT-5.1 vs Grok 3New provider

GPT-5.1 vs Llama 4 MaverickNew provider

Updated Nov 2025

Our Verdict

GPT-5.1

Kimi K2 ThinkingRunner-up

No community votes yet. On paper, GPT-5.1 has the edge — bigger context window, major provider backing.

Kimi K2 Thinking is 4.0x cheaper per token — worth considering if cost matters.

Too close to call

API pricing

Cost per 1M tokens

GPT-5.1

Input

$1.25

Output

$10.00

Kimi K2 Thinking

Input

$0.60

2.1× cheaper

Output

$2.50

4.0× cheaper

Kimi K2 Thinking is cheaper on both — 2.1× input, 4.0× output

Writing DNA

Style Comparison

Similarity

47%

Kimi K2 Thinking uses 2.1x more transitions

GPT-5.1

Kimi K2 Thinking

62%Vocabulary57%

19wSentence Length26w

0.29Hedging0.36

3.5Bold5.8

7.2Lists6.0

0.00Emoji0.00

0.61Headings0.56

0.03Transitions0.06

Based on 14 + 14 text responses

Research

What we learned reading every model

GPT-5.1 and Kimi K2 Thinking have opinions about your brand too.Ask 10 models what they tell people about you. Verbatim receipts.Run the mirror

FAQ

Common questions

Keep exploring

More comparisons

GPT-5.1 vs MiniMax M3New provider

GPT-5.1 vs Grok 3New provider

GPT-5.1 vs Llama 4 MaverickNew provider