![[Completely Free] The Complete Guide to Using LMArena: An Innovative Platform for Fairly Comparing AI Models](/guides-media/bd66787a-Screenshot-2025-08-20-at-22.40.35-scaled.jpg)
LMArena (Large Model Arena) is a platform for comparing a wide range of AI models objectively and for free. This service's biggest feature is its blind-testing system, in which users compare responses without being told which model produced each one.
What makes LMArena innovative is that it allows fair evaluation without preconceptions. Model names are revealed only after you vote, so evaluations are based on actual performance rather than marketing buzzwords.
Key Features
- Completely free: No special registration or login required
- Anonymous evaluation system: Compares responses with model names hidden
- Elo rating: Rankings based on user votes
- Support for the latest models: Test the newest models from major companies such as OpenAI, Google, Anthropic, and Mistral
Basic Usage of LMArena
Step 1: Access the Site
First, open lmarena.ai in your browser. No special registration is needed, so you can start using it right away.
Step 2: Choose a Feature
In LMArena, you can switch between the following features using the tabs at the top of the screen:
- Battle (Chat): Compare text-generation AIs
- Side by Side: Compare generative AIs
- Direct Chat: Choose a generative AI to use directly
Detailed Usage of Each Feature
Below, we explain in detail how to use LMArena's main features: “Battle,” “Side by Side,” and “Direct Chat.”
Battle: Comparing Generative AIs
The Battle feature lets you vote on which of two generative AIs' responses is better, in a blind comparison.
1. Enter a prompt
Select “Battle” on the site and enter your question or instructions (a prompt).
2. Response generation
Two different AI models respond to the same prompt. The responses are shown without revealing which model produced which.
3. Compare and vote
Click to select whichever response (A or B) you think is better.
4. View results and learn
After you vote, you finally learn which AI model produced each response. Your vote is reflected in the Elo rating, updating the models' rankings.
Main use cases: Ideal when you want to fairly compare each model's real ability, or when you want to know actual performance without the marketing spin.
Side by Side: Comparing Generative AIs
Side by Side is a feature that displays the responses of multiple generative AIs side by side, letting you directly compare their content.
1. Enter a prompt
Enter your question or instructions in the “Side by Side” tab.
2. Model selection (if applicable)
Either choose the AI models you want yourself, or let the platform automatically select multiple models.
3. View responses
Responses from multiple models (typically 3 to 5) are displayed side by side, letting you see the differences between them at a glance.
4. Compare and analyze
You can closely compare and analyze the content, quality, and style of each (a voting feature may not always be available).
Main use cases: Recommended when you want a bird's-eye view of multiple AIs' strengths and weaknesses, or when you need detailed analysis for research or work purposes.
Direct Chat: Choosing and Using a Generative AI
Direct Chat is a feature that lets you specify whichever generative AI model you like and chat or generate content with it directly.
1. Select an AI model
In the “Direct Chat” tab, explicitly select the AI model you want (for example, ChatGPT, Claude, or Gemini).
2. Start chatting
Enter a prompt, question, or instruction to start a conversation or generate content.
3. How to use it
You can use it for a variety of purposes, including general questions, creative output, code generation, and image generation (for models that support it).
Main use cases: Convenient when you want to experience a specific AI model's capabilities on its own, run tests suited to real work, or do prompt tuning and research.
What Is the Leaderboard?
LMArena's Leaderboard is a public ranking that quantifies votes gathered through Battle, Side by Side, and other features into an Elo rating, ranking generative AI models against each other.
- The stronger the opponent you beat, the more points you gain, and the more points you lose for losing to a weaker opponent, so a lucky win alone won't keep a model at the top.
- The ranking updates automatically every few hours to a few days, and the standings shift every time a new model, such as GPT-5 or Gemini 2.5 Pro, is added.
Benefits of Using LMArena
Business Use
LMArena is especially valuable for small businesses because it lets you compare performance under realistic work conditions before committing to an expensive rollout. It can be used for purposes such as:
- Comparing performance before adopting an AI tool
- Selecting the model best suited to improving work efficiency
- Objectively evaluating multiple AI services
Learning and Research Use
- Tracking performance trends of the latest AI models
- Understanding AI's capabilities and limitations
- Practicing prompt engineering
Conclusion
LMArena is an innovative platform that enables neutral, fair comparison of AI models through its anonymous evaluation system. You can test the latest models, including Google Gemini, ChatGPT, and Claude, for free, and get an objective evaluation based on actual performance rather than marketing bias.
If you're considering selecting or adopting an AI tool, we recommend starting with a free test on LMArena to find the model best suited to your needs. Additional specialized evaluation tools are planned for the future, making it an important platform for keeping up with trends in the AI industry as well.