Should You Speak English to AI? A Practical Guide to Cost Reduction and Performance Enhancement

Should You Speak English to AI? A Practical Guide to Cost Reduction and Performance Enhancement

Speaking Japanese to AI Might Be "Losing Money"

Super Practical Techniques: How English Can Dramatically Reduce Costs and Unlock AI Performance

【Important: Please Read First】

The information in this article is based on research as of September 24, 2025. Generative AI technology, pricing structures, and tokenization specifications may change without notice due to updates from various companies. The prices and figures mentioned are purely illustrative examples.

When using actual services, please always verify the latest accurate information on official websites and use it at your own judgment and responsibility.

Introduction: What's the Real Cause of Your AI Cost Problem?

Everyone has their own relationship with generative AI. For those who use services like ChatGPT for daily conversations and brainstorming, the main concern might be "hitting the free plan limits too quickly."

However, for developers and power users who leverage AI agents (like Cursor) for development or integrate APIs into their services, the real headache is the "pay-per-use" costs snowballing out of control.

💸 Why Traditional Solutions No Longer Work

Previously, there was an approach where you could somewhat stabilize costs by using specific models like Codex. However, recently even these models have strict usage limits and time restrictions (rate limits), and it's not uncommon to see merciless notifications like "You can't use this for another X hours" at crucial moments.

🎯 The Real Challenge We Must Face Now

So there's one challenge we really need to confront:

How to use top-performance "professional-grade" models like GPT-5 and Gemini 2.5 Pro smartly, efficiently, and sustainably.

In this article, I propose the simplest yet most powerful solution to this challenge:

💡 Solution: "Switch your primary AI conversations from Japanese to English"

🔰 Middle School English Is Enough

And don't worry. The English I'm talking about here is definitely not fluent business English.

• Simple vocabulary and grammar from middle school level is sufficient
• AI can intelligently understand even if some Japanese is mixed in
• You can start casually without aiming for perfection

This article provides a thorough explanation based on the latest data and facts about specific methods and why this dramatically reduces costs, improves AI response speed and quality, and even enhances your English skills.

Part 1: The Inconvenient Truth. Why Japanese Is a "Fuel-Inefficient Language" for AI

AI doesn't understand language like humans do. It breaks down text into units called "Tokens" and processes their relationships mathematically. And this "Token" is the fundamental reason why Japanese users are at a disadvantage cost-wise.

📊 Fact: Japanese Consumes More Tokens Than English

Due to language characteristics, the same amount of information creates significant differences in token consumption.

• Words are separated by spaces, so they're efficiently tokenized in "word" or "sub-word" units
• Example: "AI is powerful." → About 4 tokens

For English

• There are no word boundaries, so text tends to be tokenized into character or short morpheme units
• Example: 「AIはパワフルです。」 → About 10 tokens

For Japanese

⚠️ Important Fact
To convey the same information, Japanese sends 1.5 to 3+ times the "data volume" to AI compared to English. This ratio varies depending on the content and AI model.

💰 Data: The "Output Token" Trap That Dominates Costs

Most AI API pricing is set up as follows:

• Input tokens: Instructions humans send to AI
• Output tokens: Responses AI generates and returns

And "output" where AI generates text is generally priced higher than "input" where humans give instructions.

⚠️ Note: The above prices are examples for illustration. Please always check the latest pricing on official websites.

💸 Actual Cost Calculation: Requesting Report Creation

Let's compare the costs when requesting the same content report.

• Total tokens (estimated): About 12,000 tokens
• GPT-5 cost (estimated): About $0.29

Japanese instruction・Japanese output

• Total tokens (estimated): About 4,000 tokens
• GPT-5 cost (estimated): About $0.09

English instruction・English output

📊 Analysis Result
As this calculation shows, just the difference in language can create a 3x+ difference in costs.

Part 2: Four Benefits You Can Expect from Switching to English

Cost reduction is just the beginning. Making English your working language with AI can further improve your productivity.

💰 Benefit ①: Improved Cost Performance

As mentioned above, you can expect dramatically improved cost efficiency compared to Japanese for API fees and paid plan usage limits.

🎯 Benefit ②: Improved Answer "Quality" and "Freshness"

• Major AI models worldwide are said to be composed primarily of English text in their training data
• Especially for specialized fields, latest technology, and niche topics, asking in English is advantageous

Impact of Training Data Language Ratio

• Deeper, more accurate responses based on the latest information are likely to be returned
• The abundance of technical documents and documentation is reflected

Expected Effects

⚡ Benefit ③: Improved AI Response Speed

• Generally, the fewer tokens AI generates, the shorter the processing time tends to be
• English output requires fewer tokens than Japanese, so AI responses may become faster

Impact on Processing Speed

⚠️ Note: Speed is also affected by other factors like server congestion

🏋️ Benefit ④: Becomes a Practical "English Gym"

• Do you feel like "my English skills are declining..."?
• AI can be your English "practice partner" 24/7/365

Continuous English Learning Opportunities

• Since AI can understand your intent even with some grammar mistakes, you can work without fear of imperfection
• You can conduct practical reading (reading AI responses) and writing (giving instructions) training in your daily work

Learning Effects

Part 3: Start Today! AI English Utilization・Practical Steps

You don't need to switch everything to English immediately. You can start with simple steps.

🔰 Suggestion 1: Don't Overthink It! Middle School English Is Enough, Japanese Mixed In Is OK

• AI has very high contextual understanding ability, so perfect sentences aren't necessary
• Even just lining up keywords, AI can understand your intent
• If you can't think of difficult words, using just Japanese for those parts is fine

Leverage AI's High Contextual Understanding

• React component, カードデザイン, sample code please
• summary, this article, 3 points
• function, calculates 消費税, input is price

Good Examples: Mixed Language Instructions

🛠️ Suggestion 2: Use Translation Tools as Your "Crutch"

• Always keep DeepL or Google Translate by your side
• First translate instructions you think in Japanese to English using translation tools, then send to AI
• This alone can reduce input costs

Efficient Input Cost Reduction Method

🚀 Suggestion 3: Try the Ultimate Workflow "Generate in English → Human Translation"

3-Step Efficient Workflow

1. Give instructions (prompts) in simple English
2. Receive AI responses in English too, of course
3. Copy the entire English response and run it through translation tools as needed

💡 This procedure is, in many cases, one of the most cost-, speed-, and quality-balanced AI utilization techniques.

👨‍🏫 Suggestion 4: Make AI Your "English Teacher"

• Don't worry if you're not confident in your English
• Have AI correct it for you
• Try adding the following "magic spell" at the end of your prompts

Utilize English Correction Features

Correction Request Template

First, please correct and improve my English prompt for clarity and effectiveness. Then, answer the improved prompt.

This way, AI will correct your English and teach you better ways to give instructions.

Conclusion: Tomorrow's Standard, In Your Hands Today

Switching AI interactions from Japanese to English isn't just a cost-cutting technique.

🌟 The Essence of This Approach

It's an extremely strategic self-investment that maximizes AI tool performance, provides direct access to global information, and simultaneously sharpens your English skills.

🚀 Action Starting Today

You don't need to aim for perfect English.

Starting today, why not incorporate just a little "casual English" into your AI conversations?

That small step might become the trigger that dramatically changes your productivity and future.

I hope this article helps make your AI utilization more efficient and practical. 🤖✨