What is the difference between GPT-5.1-Codex and Grok Code Fast 1?

GPT-5.1-Codex is developed by OpenAI while Grok Code Fast 1 is developed by xAI. GPT-5.1-Codex has a 400K token context window vs Grok Code Fast 1's 256K. You can compare their actual outputs across 53 challenges on Rival to see how they differ in practice.

Which is better, GPT-5.1-Codex or Grok Code Fast 1?

It depends on your use case. GPT-5.1-Codex and Grok Code Fast 1 each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 53 challenges so you can judge which fits your needs best.

How much does GPT-5.1-Codex cost compared to Grok Code Fast 1?

GPT-5.1-Codex costs $1.25/M input tokens and Grok Code Fast 1 costs $0.2/M input tokens. Grok Code Fast 1 is $1.05/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-Codex and Grok Code Fast 1 on Rival?

This page shows a side-by-side comparison of GPT-5.1-Codex and Grok Code Fast 1 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-Codex and Grok Code Fast 1?

GPT-5.1-Codex is developed by OpenAI while Grok Code Fast 1 is developed by xAI. GPT-5.1-Codex has a 400K token context window vs Grok Code Fast 1's 256K. You can compare their actual outputs across 53 challenges on Rival to see how they differ in practice.

Which is better, GPT-5.1-Codex or Grok Code Fast 1?

It depends on your use case. GPT-5.1-Codex and Grok Code Fast 1 each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 53 challenges so you can judge which fits your needs best.

How much does GPT-5.1-Codex cost compared to Grok Code Fast 1?

GPT-5.1-Codex costs $1.25/M input tokens and Grok Code Fast 1 costs $0.2/M input tokens. Grok Code Fast 1 is $1.05/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-Codex and Grok Code Fast 1 on Rival?

This page shows a side-by-side comparison of GPT-5.1-Codex and Grok Code Fast 1 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.

Updated Nov 2025

GPT-5.1-CodexvsGrok Code Fast 1

Grok Code Fast 1 is cheaper than GPT-5.1-Codex at $0.2/M vs $1.25/M input tokens.

GPT-5.1-Codex and Grok Code Fast 1 compared across 53 shared prompts
Spec	GPT-5.1-Codex	Grok Code Fast 1
Input price	$1.25/M tokens	$0.2/M tokens
Output price	$10/M tokens	$1.5/M tokens
Context window	400K tokens	256K tokens
Released	Nov 2025	Aug 2025
SWE-bench Verified	73.7%	70.8%

Our Verdict

GPT-5.1-Codex

Grok Code Fast 1Runner-up

Not enough votes to call it. On the specs, GPT-5.1-Codex has the edge: bigger model tier, newer, bigger context window.

Grok Code Fast 1 costs 6.7x less per token.

Slight edge

What do GPT-5.1-Codex and Grok Code Fast 1 say about your brand?

10 models, one question, verbatim receipts.

or peek at a demo: Notion Linear Vercel

API pricing

Cost per 1M tokens

GPT-5.1-Codex

Input

$1.25

Output

$10.00

Grok Code Fast 1

Input

$0.20

6.3× cheaper

Output

$1.50

6.7× cheaper

Grok Code Fast 1 is cheaper on both — 6.3× input, 6.7× output

Writing DNA

Style Comparison

Similarity

63%

Grok Code Fast 1 uses 6.0x more emoji

GPT-5.1-Codex

Grok Code Fast 1

70%Vocabulary60%

17wSentence Length17w

0.39Hedging0.97

3.4Bold2.8

3.5Lists2.5

0.00Emoji0.06

0.50Headings0.89

0.38Transitions0.11

Based on 14 + 23 text responses

Research

What we learned reading every model

FAQ

Common questions

Keep exploring

More comparisons

Grok Code Fast 1 vs MiniMax M3New provider

Grok Code Fast 1 vs Ox AlphaNew provider

Grok Code Fast 1 vs Claude Opus 4New provider

Grok Code Fast 1 vs Claude Opus 4.1New provider

Grok Code Fast 1 vs Claude Sonnet 4.6New provider

Grok Code Fast 1 vs Claude Sonnet 5New provider

Grok Code Fast 1 vs OpenAI Codex MiniCross-provider

GPT-5.1-Codex vs Cypher Alpha (free)New provider

Updated Nov 2025

GPT-5.1-CodexvsGrok Code Fast 1

Grok Code Fast 1 is cheaper than GPT-5.1-Codex at $0.2/M vs $1.25/M input tokens.

GPT-5.1-Codex and Grok Code Fast 1 compared across 53 shared prompts
Spec	GPT-5.1-Codex	Grok Code Fast 1
Input price	$1.25/M tokens	$0.2/M tokens
Output price	$10/M tokens	$1.5/M tokens
Context window	400K tokens	256K tokens
Released	Nov 2025	Aug 2025
SWE-bench Verified	73.7%	70.8%

Our Verdict

GPT-5.1-Codex

Grok Code Fast 1Runner-up

Not enough votes to call it. On the specs, GPT-5.1-Codex has the edge: bigger model tier, newer, bigger context window.

Grok Code Fast 1 costs 6.7x less per token.

Slight edge

What do GPT-5.1-Codex and Grok Code Fast 1 say about your brand?

10 models, one question, verbatim receipts.

or peek at a demo: Notion Linear Vercel

API pricing

Cost per 1M tokens

GPT-5.1-Codex

Input

$1.25

Output

$10.00

Grok Code Fast 1

Input

$0.20

6.3× cheaper

Output

$1.50

6.7× cheaper

Grok Code Fast 1 is cheaper on both — 6.3× input, 6.7× output

Writing DNA

Style Comparison

Similarity

63%

Grok Code Fast 1 uses 6.0x more emoji

GPT-5.1-Codex

Grok Code Fast 1

70%Vocabulary60%

17wSentence Length17w

0.39Hedging0.97

3.4Bold2.8

3.5Lists2.5

0.00Emoji0.06

0.50Headings0.89

0.38Transitions0.11

Based on 14 + 23 text responses

Research

What we learned reading every model

FAQ

Common questions

Keep exploring

More comparisons

Grok Code Fast 1 vs MiniMax M3New provider

Grok Code Fast 1 vs Ox AlphaNew provider

Grok Code Fast 1 vs Claude Opus 4New provider

Grok Code Fast 1 vs Claude Opus 4.1New provider

Grok Code Fast 1 vs Claude Sonnet 4.6New provider

Grok Code Fast 1 vs Claude Sonnet 5New provider

Grok Code Fast 1 vs OpenAI Codex MiniCross-provider

GPT-5.1-Codex vs Cypher Alpha (free)New provider