What is the difference between xAI: Grok 4 Fast (free) and Grok 4.20 Beta?

Both are developed by xAI but target different use cases. xAI: Grok 4 Fast (free) has a 2.0M token context window vs Grok 4.20 Beta's 2.0M. You can compare their actual outputs across 34 challenges on Rival to see how they differ in practice.

Which is better, xAI: Grok 4 Fast (free) or Grok 4.20 Beta?

It depends on your use case. xAI: Grok 4 Fast (free) and Grok 4.20 Beta each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 34 challenges so you can judge which fits your needs best.

How much does xAI: Grok 4 Fast (free) cost compared to Grok 4.20 Beta?

xAI: Grok 4 Fast (free) costs $0/M input tokens and Grok 4.20 Beta costs $2/M input tokens. xAI: Grok 4 Fast (free) is $2.00/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 xAI: Grok 4 Fast (free) and Grok 4.20 Beta on Rival?

This page shows a side-by-side comparison of xAI: Grok 4 Fast (free) and Grok 4.20 Beta 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 xAI: Grok 4 Fast (free) and Grok 4.20 Beta?

Both are developed by xAI but target different use cases. xAI: Grok 4 Fast (free) has a 2.0M token context window vs Grok 4.20 Beta's 2.0M. You can compare their actual outputs across 34 challenges on Rival to see how they differ in practice.

Which is better, xAI: Grok 4 Fast (free) or Grok 4.20 Beta?

It depends on your use case. xAI: Grok 4 Fast (free) and Grok 4.20 Beta each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 34 challenges so you can judge which fits your needs best.

How much does xAI: Grok 4 Fast (free) cost compared to Grok 4.20 Beta?

xAI: Grok 4 Fast (free) costs $0/M input tokens and Grok 4.20 Beta costs $2/M input tokens. xAI: Grok 4 Fast (free) is $2.00/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 xAI: Grok 4 Fast (free) and Grok 4.20 Beta on Rival?

This page shows a side-by-side comparison of xAI: Grok 4 Fast (free) and Grok 4.20 Beta 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.

xAI: Grok 4 Fast (free) vs Grok 4.20 Beta: Which Is Better?

Updated Mar 2026

Our Verdict

Grok 4.20 Beta

xAI: Grok 4 Fast (free)Runner-up

No community votes yet. On paper, Grok 4.20 Beta has the edge — bigger model tier, newer.

Too close to call

API pricing

Cost per 1M tokens

xAI: Grok 4 Fast (free)

Input

$0.000

Output

$0.000

Grok 4.20 Beta

Input

$2.00

Output

$6.00

Writing DNA

Style Comparison

Similarity

49%

Grok 4.20 Beta uses 3.0x more bold

xAI: Grok 4 Fast (free)

Grok 4.20 Beta

65%Vocabulary57%

13wSentence Length20w

0.56Hedging0.35

1.4Bold4.2

2.5Lists3.7

0.00Emoji0.00

1.58Headings0.62

0.28Transitions0.14

Based on 14 + 23 text responses

Research

What we learned reading every model

xAI: Grok 4 Fast (free) and Grok 4.20 Beta 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

xAI: Grok 4 Fast (free) vs MiniMax M3New provider

xAI: Grok 4 Fast (free) vs GPT-5New provider

xAI: Grok 4 Fast (free) vs Pony AlphaNew provider

Updated Mar 2026

Our Verdict

Grok 4.20 Beta

xAI: Grok 4 Fast (free)Runner-up

No community votes yet. On paper, Grok 4.20 Beta has the edge — bigger model tier, newer.

Too close to call

API pricing

Cost per 1M tokens

xAI: Grok 4 Fast (free)

Input

$0.000

Output

$0.000

Grok 4.20 Beta

Input

$2.00

Output

$6.00

Writing DNA

Style Comparison

Similarity

49%

Grok 4.20 Beta uses 3.0x more bold

xAI: Grok 4 Fast (free)

Grok 4.20 Beta

65%Vocabulary57%

13wSentence Length20w

0.56Hedging0.35

1.4Bold4.2

2.5Lists3.7

0.00Emoji0.00

1.58Headings0.62

0.28Transitions0.14

Based on 14 + 23 text responses

Research

What we learned reading every model

xAI: Grok 4 Fast (free) and Grok 4.20 Beta 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

xAI: Grok 4 Fast (free) vs MiniMax M3New provider

xAI: Grok 4 Fast (free) vs GPT-5New provider

xAI: Grok 4 Fast (free) vs Pony AlphaNew provider