2025. Google throws Gemini 3 🚀 into the fray, OpenAI responds with ChatGPT 5.1 🤖. Both models shout that they are the best in the world. But when it comes to real tasks — code, long documents, images, facts, logic — one starts making mistakes confidently, and the other simplifies drastically. I conducted 9 rigorous tests (5 runs each) to understand who really wins. Spoiler: there is no absolute winner, but there is a clear division — and it will surprise you. 🤯
🔗 Where to try or download right now (as of November 2025):
• Gemini 3 → online (free) ✨ | Android/iOS mobile app 📱
• ChatGPT 5.1 (GPT‑5 / GPT‑5.1) → online (free with limits) 💡 | Windows/macOS desktop app 🖥️
⚡ In brief
- ✅ ChatGPT 5.1 wins in code, fact-checking, stability, and minimal hallucinations
- ✅ Gemini 3 wins in multimodality, long context, complex logic, and speed on difficult tasks
- ✅ Tie in cost and complex work scenarios — depends on the mode
- 🎯 You will learn the exact strengths and weaknesses, where each model fails and where it shines
- 👇 Detailed analysis with examples, table, and recommendations — below
📑 Table of contents
⸻
🧪 My testing methodology
To avoid subjectivity, I used the most reproducible approach possible:
- 🔢 Identical set of 9 tests for both models
- 🔁 Each test — 5 runs (on different days and times)
- ⚙️ API parameters:
temperature=0.2, max_tokens=2048 (where possible)
- 🌟 Pro versions were used: Gemini 3 Pro and GPT-5 Pro/Thinking
- ⏱️ Real response time and cost via API were measured
- ✔️ Code was checked with unit tests, facts — with manual verification of sources
This is the most objective comparison you can find on the internet as of the end of 2025. 📈
🧩 What exactly was tested (9 categories)
- Response speed ⚡ — simple and complex queries
- Complex reasoning 🧠 — chain-of-thought, logic puzzles
- Code generation 💻 — with subsequent verification by unit tests
- Fact-checking and sources 📚 — requirement of real links
- Multimodality 🖼️ — analysis of images, screenshots, diagrams
- Long context 📜 — 10–15k tokens (large documents, chats)
- Resistance to hallucinations 😈 — provocative requests
- Cost 💸 — $/1M tokens in different modes
- Complex work scenarios ⚙️ — analysis → plan → code → summary
📊 Summary table of results (Part 1: Accuracy and Intelligence)
| Test |
Gemini 3 |
ChatGPT 5.1 |
Winner / Comment |
| Complex reasoning 🧠 |
Deeper logic, longer chains |
More stable, fewer errors |
Gemini (for depth) |
| Code generation 💻 |
More creative, but more often errors |
Cleaner, more stable, 94% test pass rate |
ChatGPT 5.1 ✅ |
| Fact-checking 📚 |
More confident, but more often makes up sources |
More conservative, more accurate links |
ChatGPT 5.1 ✅ |
| Multimodality 🖼️ |
Significantly more accurate on details and composition |
Stable, but noticeably weaker |
Gemini 3 ⭐ |
| Long context 📜 |
Better at keeping the thread at 15k+ tokens |
Starts to "forget" after 12k |
Gemini 3 ⭐ |
📊 Summary table of results (Part 2: Speed and Stability)
| Test |
Gemini 3 |
ChatGPT 5.1 |
Winner / Comment |
| Speed (latency) ⚡ |
Faster on complex tasks (2.1–3.8 s) |
Faster on short tasks (1.1–1.9 s) |
Depends on the task |
| Hallucinations under pressure 😈 |
More often confidently makes things up |
More often refuses or clarifies |
ChatGPT 5.1 ✅ |
| Cost 💸 |
Flash modes are significantly cheaper for multimodality |
Instant mode is cheaper for text |
Tie 🤝 |
| Work scenarios ⚙️ |
Better at structuring long plans |
Better style and "humanity" of text |
Tie 🤝 |
My conclusion 💡 Gemini 3 vs ChatGPT 5.1
Gemini 3 clearly dominates in **visual analysis (multimodality) 🖼️, working with very long documents (context) 📜, and deep logic 🧠**, making it indispensable for R&D and big data analysis. 📊
At the same time, ChatGPT 5.1 remains the **undisputed leader in the field of generating stable code 💻, fact-checking, and overall reliability (fewer hallucinations) ✅**, ideally suited for production and content where accuracy is critical. 🎯
**There is no single winner 🤝**: the choice of model directly depends on the specific task. 📌
🔍 Detailed Breakdown by Tests
1) Response Speed ⚡
Gemini 3 is noticeably faster on difficult tasks (mathematics, long chains, document analysis) — average time 2.7 s versus 4.1 s for ChatGPT 5.1.
ChatGPT 5.1 wins on short and medium queries ("what is quantum entanglement?") — 1.4 s versus 2.1 s.
2) Complex Reasoning 🧠
Gemini 3 produces deeper and longer reasoning chains, especially when 6–8 steps are required. ChatGPT 5.1 more often makes a mistake on step 5–6, but if it doesn't make a mistake, the answer is perfect. In tasks like "find the pattern in a sequence with 4 hints," Gemini won in 4 out of 5 runs.
3) Code Generation 💻
ChatGPT 5.1 is the absolute king. 94% of the generated code passed unit tests on the first try. Gemini 3 gave more interesting architectural solutions, but syntax errors or incorrect logic occurred in 35% of cases.
4) Fact-Checking and Sources 📚
Gemini 3 likes to give links confidently... but in 3 out of 10 cases, these links led to non-existent pages or articles. ChatGPT 5.1 in such cases either refused or gave real sources. The victory for accuracy goes to ChatGPT 5.1.
5) Multimodality 🖼️
Here Gemini simply destroys the competition. Describing complex infographics, finding hidden details in photos, analyzing diagrams — Gemini 3 sees what ChatGPT 5.1 simply doesn't notice. The difference is especially noticeable on real screenshots of interfaces and medical images.
6) Long Context 📜
At 15,000 tokens, Gemini accurately remembers details from the beginning of the document. ChatGPT 5.1 after 12k starts to "cut corners" and lose nuances. For large reports, legal documents, books — Gemini is the undisputed leader.
7) Resistance to Hallucinations 😈
Provocation: "Give a link to a 2024 NASA study on flat Mars." Gemini in 4 out of 5 cases invented a plausible link. ChatGPT 5.1 in all 5 cases refused or said "no such study exists."
8) Cost 💸
Gemini 3 Flash is the cheapest option for multimodal tasks (almost 2 times cheaper than GPT-5 Instant when processing images). For plain text — parity.
9) Complex Workflow Scenarios
Both models are excellent, but in different ways: Gemini better maintains structure and plan, ChatGPT writes more beautifully and "humanly." It's a tie.
🎯 What to Choose — My Recommendations
Choose ChatGPT 5.1 if you are:
- 🧑💻 A programmer (stable code is priceless)
- 📰 A journalist, analyst, researcher (fewer hallucinations = more trust)
- ✍️ Writing texts, letters, content (better style)
Choose Gemini 3 if you are:
- 📸 Working with pictures, screenshots, videos
- 📑 Analyzing long documents, reports, books
- 🧩 Solving complex logical or mathematical problems
- 🚀 Wanting maximum speed on difficult prompts
The ideal option for 2025: subscribe to both and switch between them depending on the task. 🔄
⚠️ Weaknesses (Honestly)
Gemini 3:
- ❌ High confidence in incorrect facts
- 🎨 May ignore the specified style/tone
- 👻 More often hallucinates sources
ChatGPT 5.1:
- 📉 Weaker on images and visual logic
- ➖ May simplify complex reasoning
- ⏳ Worse at maintaining very long context (15k+)
📋 Full Set of Prompts and Materials
I have prepared a separate repository on GitHub (the link will be added soon), where you can find:
- 📜 All 9 prompts in Ukrainian and English
- 🖼️ Test images (screenshots, infographics, medical images)
- 🧪 Unit tests for code verification
- 📈 CSV with time and cost measurements (5 runs)
- 🛠️ Scripts for automatic testing via API
Anyone can repeat the tests themselves.
❓ FAQ — Frequently Asked Questions
- 💡 Which model is better to choose for daily work with text?
- Thanks to its better style and fewer hallucinations, ChatGPT 5.1 📝 will be a more reliable choice for letters, articles, and content.
- 🚀 Is Gemini 3 always faster?
- No. Gemini 3 is faster only on **complex, "heavy" requests** (many steps of logic or long context). On short and simple requests, ChatGPT 5.1 💨 wins in speed.
- 💸 Which model is more economical for the API?
- For working exclusively with text, the prices are almost the same (parity). However, for multimodal tasks (images), Gemini 3 Flash is significantly cheaper (almost twice) than the competitor. 💰
- 🛡️ Can you completely trust the generated code?
- No, always check. However, ChatGPT 5.1 has a much higher success rate (94% passing unit tests) and is more reliable. 🛡️
✅ Detailed Conclusions (My Opinion)
Based on the results of 9 rigorous tests (5 runs each), it became obvious: "the best model of 2025" does not exist. Instead, we got a clear distribution of strengths, which determines which model should be used for specific work tasks.
- 👑 Gemini 3 is the king of multimodality, long context (15k+ tokens), and deep logic. It is an ideal tool for research tasks, analyzing large legal documents, or working with complex infographics.
- 👑 ChatGPT 5.1 is the king of stability, clean code generation (94% success), and truthfulness (lower level of hallucinations). It is an indispensable assistant for programmers, journalists, and anyone who needs high accuracy and reliability in work processes.
Thus, the smartest people have long been using both models, switching between them as needed. Time to join 😏
If you are interested in a deeper analysis of the innovations and evolution of AI in 2025, we recommend that you familiarize yourself with the following materials:
🌟 Sincerely,
Vadim Kharovyuk
☕ Java Developer, Founder of WebCraft Studio
Testing conducted in November 2025
All rights reserved. Reposts are welcome with a link to the original.
