Greek vs English Prompts: I Ran the Test — The Difference Surprised Me

The Question Everyone Asks

Every Greek person using ChatGPT has wondered this at some point: Should I write my prompts in Greek or English?

I've heard all the theories. "English gives better results because the training data is mostly English." Or "Greek works fine now, the models have improved." But nobody seemed to have actual data.

So I ran my own test. Same tasks, same complexity, Greek vs English prompts. Here's what I found.

The Setup

I tested five common tasks across GPT-4 and Claude:

1. Writing a professional email
2. Explaining a technical concept
3. Creating a marketing headline
4. Summarizing a Greek news article
5. Generating creative story ideas

For each task, I wrote the prompt first in Greek, then translated it to English myself (not machine-translated). I kept the structure identical.

Test 1: Professional Email

Greek prompt:

prompt Γράψε ένα επαγγελματικό email σε πελάτη που ζητάει έκπτωση. Πρέπει να αρνηθώ ευγενικά αλλά να κρατήσω τη σχέση. Η εταιρεία πουλάει λογισμικό.

English prompt:

prompt Write a professional email to a client asking for a discount. I need to politely decline but maintain the relationship. The company sells software.

Result: Nearly identical quality. The Greek response came in Greek, the English in English. Both were professional, both hit the right tone. No winner here.

Test 2: Technical Explanation

Greek prompt:

prompt Εξήγησέ μου τι είναι το API σαν να είμαι 10 χρονών. Χρησιμοποίησε καθημερινά παραδείγματα.

English prompt:

prompt Explain what an API is like I'm 10 years old. Use everyday examples.

Result: Here's where it got interesting. The English response used more creative analogies — restaurants, waiters, menus. The Greek response was accurate but felt more textbook-like.

Small edge to English.

Test 3: Marketing Headlines

This one surprised me most.

Greek prompt:

prompt Δημιούργησε 5 headlines για διαφήμιση ελληνικού ελαιόλαδου. Στόχος: νέοι καταναλωτές 25-35.

English prompt:

prompt Create 5 headlines for a Greek olive oil ad. Target: young consumers 25-35.

Result: The Greek prompt produced headlines that actually sounded Greek. Natural phrasing, cultural references that made sense. The English prompt gave me headlines that felt translated — technically correct but not how a Greek person would speak.

Clear win for Greek when the output needs to be in Greek.

Test 4: Summarizing Greek Content

I pasted a Greek news article and asked for a summary.

Greek prompt:

prompt Συνόψισε αυτό το άρθρο σε 3 σημεία. Κράτα μόνο τα βασικά.

English prompt:

prompt Summarize this article in 3 bullet points. Keep only the essentials.

Result: Identical quality. Both understood the Greek text perfectly. The language of the prompt didn't affect comprehension at all.

Test 5: Creative Ideas

Greek prompt:

prompt Δώσε μου 5 ιδέες για μικρές ιστορίες που διαδραματίζονται στην Αθήνα. Σύγχρονη εποχή, ρεαλιστικές.

English prompt:

prompt Give me 5 ideas for short stories set in Athens. Modern day, realistic.

Result: The Greek prompt generated ideas with more local flavor — specific neighborhoods, cultural situations that felt authentic. The English prompt gave me more generic "European city" ideas.

Another win for Greek when cultural context matters.

What Actually Matters

After running these tests, here's my take:

Use Greek when:

• Your final output needs to be in Greek
• Cultural context or local references matter
• You're working with Greek source material

Use English when:

• You want slightly more creative/varied responses
• You're learning prompting techniques from English resources
• The output will be in English anyway

But here's the real insight: the language of your prompt matters less than the clarity of your prompt.

A vague English prompt loses to a specific Greek prompt every time. And vice versa.

The Hybrid Approach

What I do now is mix them. I write my main instructions in whatever language feels natural for that task. But I always add specific details in the language of the expected output.

Like this:

prompt Write a product description for a leather bag. Target audience: Greek women 30-45. Use a warm, conversational tone. Η περιγραφή πρέπει να είναι στα ελληνικά, 100-150 λέξεις.

This hybrid approach consistently gives me the best results.

The Takeaway

Stop worrying about Greek vs English. Worry about being specific.

The models understand both languages well enough. What they need is clear instructions, concrete examples, and defined expectations.

Write in whatever language helps you think more clearly. That's your best prompt.