What is the difference between ChatGPT-4o (March 2025) and Z.ai: GLM 5.1?

ChatGPT-4o (March 2025) is developed by OpenAI while Z.ai: GLM 5.1 is developed by Z-ai. ChatGPT-4o (March 2025) has a 128K token context window vs Z.ai: GLM 5.1's 203K. You can compare their actual outputs across 31 challenges on Rival to see how they differ in practice.

Which is better, ChatGPT-4o (March 2025) or Z.ai: GLM 5.1?

It depends on your use case. ChatGPT-4o (March 2025) and Z.ai: GLM 5.1 each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 31 challenges so you can judge which fits your needs best.

How much does ChatGPT-4o (March 2025) cost compared to Z.ai: GLM 5.1?

ChatGPT-4o (March 2025) costs $5/M input tokens and Z.ai: GLM 5.1 costs $1.4/M input tokens. Z.ai: GLM 5.1 is $3.60/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 ChatGPT-4o (March 2025) and Z.ai: GLM 5.1 on Rival?

This page shows a side-by-side comparison of ChatGPT-4o (March 2025) and Z.ai: GLM 5.1 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 ChatGPT-4o (March 2025) and Z.ai: GLM 5.1?

ChatGPT-4o (March 2025) is developed by OpenAI while Z.ai: GLM 5.1 is developed by Z-ai. ChatGPT-4o (March 2025) has a 128K token context window vs Z.ai: GLM 5.1's 203K. You can compare their actual outputs across 31 challenges on Rival to see how they differ in practice.

Which is better, ChatGPT-4o (March 2025) or Z.ai: GLM 5.1?

It depends on your use case. ChatGPT-4o (March 2025) and Z.ai: GLM 5.1 each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 31 challenges so you can judge which fits your needs best.

How much does ChatGPT-4o (March 2025) cost compared to Z.ai: GLM 5.1?

ChatGPT-4o (March 2025) costs $5/M input tokens and Z.ai: GLM 5.1 costs $1.4/M input tokens. Z.ai: GLM 5.1 is $3.60/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 ChatGPT-4o (March 2025) and Z.ai: GLM 5.1 on Rival?

This page shows a side-by-side comparison of ChatGPT-4o (March 2025) and Z.ai: GLM 5.1 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.

ChatGPT-4o (March 2025) vs Z.ai: GLM 5.1: Which Is Better?

Updated Apr 2026

Our Verdict

ChatGPT-4o (March 2025)

Z.ai: GLM 5.1

No community votes yet. On paper, these are closely matched - try both with your actual task to see which fits your workflow.

Z.ai: GLM 5.1 is 3.4x cheaper per token — worth considering if cost matters.

Too close to call

API pricing

Cost per 1M tokens

ChatGPT-4o (March 2025)

Input

$5.00

Output

$15.00

Z.ai: GLM 5.1

Input

$1.40

3.6× cheaper

Output

$4.40

3.4× cheaper

Z.ai: GLM 5.1 is cheaper on both — 3.6× input, 3.4× output

Writing DNA

Style Comparison

Similarity

31%

ChatGPT-4o (March 2025) uses 94.5x more emoji

ChatGPT-4o (March 2025)

Z.ai: GLM 5.1

55%Vocabulary54%

24wSentence Length18w

0.52Hedging0.31

3.3Bold3.6

6.0Lists2.6

0.94Emoji0.00

0.63Headings0.43

0.05Transitions0.11

Based on 15 + 27 text responses

Research

What we learned reading every model

ChatGPT-4o (March 2025) and Z.ai: GLM 5.1 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

ChatGPT-4o (March 2025) vs MiniMax M3New provider

Z.ai: GLM 5.1 vs Llama 4 MaverickNew provider

ChatGPT-4o (March 2025) vs Claude Opus 4.1New provider

Updated Apr 2026

Our Verdict

ChatGPT-4o (March 2025)

Z.ai: GLM 5.1

No community votes yet. On paper, these are closely matched - try both with your actual task to see which fits your workflow.

Z.ai: GLM 5.1 is 3.4x cheaper per token — worth considering if cost matters.

Too close to call

API pricing

Cost per 1M tokens

ChatGPT-4o (March 2025)

Input

$5.00

Output

$15.00

Z.ai: GLM 5.1

Input

$1.40

3.6× cheaper

Output

$4.40

3.4× cheaper

Z.ai: GLM 5.1 is cheaper on both — 3.6× input, 3.4× output

Writing DNA

Style Comparison

Similarity

31%

ChatGPT-4o (March 2025) uses 94.5x more emoji

ChatGPT-4o (March 2025)

Z.ai: GLM 5.1

55%Vocabulary54%

24wSentence Length18w

0.52Hedging0.31

3.3Bold3.6

6.0Lists2.6

0.94Emoji0.00

0.63Headings0.43

0.05Transitions0.11

Based on 15 + 27 text responses

Research

What we learned reading every model

ChatGPT-4o (March 2025) and Z.ai: GLM 5.1 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

ChatGPT-4o (March 2025) vs MiniMax M3New provider

Z.ai: GLM 5.1 vs Llama 4 MaverickNew provider

ChatGPT-4o (March 2025) vs Claude Opus 4.1New provider