GPT 5 vs Gemini 2.5 Pro Comparison - Ultimate Coding Test 2025

 GPT 5 vs Gemini 2.5 Pro Comparison - Ultimate Coding Test 2025 

As of August 2025, GPT-5 and Gemini 2.5 Pro are both considered top-tier large language models, but a recent "Ultimate Coding Test" shows a clear winner in coding performance.¹ GPT-5 currently leads in coding benchmarks and overall reasoning, though Gemini 2.5 Pro remains highly competitive and excels in other specific areas.

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Key Takeaways from the 2025 Ultimate Coding Test 💻

Based on recent benchmarks and expert analysis, here's a direct comparison of their coding capabilities:

• GPT-5 is the new leader in coding.² GPT-5, especially its Pro version with Python tools, has set new records on major coding benchmarks.³ It's credited with significant advancements in "vibe coding" (building apps from prompts with minimal human input) and handling long, complex agentic tasks from start to finish.⁴

• Gemini 2.5 Pro remains a strong contender.⁵ While GPT-5 has surpassed it in some coding benchmarks, Gemini 2.5 Pro is still highly regarded for its coding prowess.⁶ It's particularly praised for its ability to generate visually compelling web apps and agentic code applications from single-line prompts. Its "Deep Think" mode is specifically designed for complex problems, including competition-level coding.

• A major advantage for Gemini 2.5 Pro is its context window.⁷ With a context window of up to 1 million tokens (and 2 million on the horizon), Gemini 2.5 Pro is the industry leader in handling vast amounts of information.⁸ This is a significant advantage for coding tasks that involve analyzing large repositories or extensive documentation.⁹ GPT-5 has a 400k input token context window, which is still substantial but smaller than Gemini's.¹⁰

• Reliability and pricing are factors. GPT-5 is noted for its low hallucination rate and high reliability, especially in its Pro version. In terms of pricing, GPT-5 is competitively priced, with a cost of $1.25 per million input tokens and $10 per million output tokens.¹¹ Gemini 2.5 Pro has a similar pricing structure for small inputs, but its cost increases for larger contexts.

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Summary of Performance Across Different Metrics

While the focus is on coding, it's helpful to see a broader comparison to understand the full picture of each model's strengths.

Metric	GPT-5 (with Python tools)	Gemini 2.5 Pro	Analysis
Coding (SWE-Bench Verified)	74.9%	63.8%	GPT-5 holds a significant lead, with specific praise for its ability to complete complex, end-to-end tasks.
Reasoning (GPQA Diamond)	89.4%	86.4%	GPT-5 edges out Gemini, but both models demonstrate extremely strong reasoning capabilities.
Math (AIME 2025)	100% accuracy	86.7%	GPT-5's performance in math is exceptional, achieving a perfect score with its "thinking" and tool use capabilities.
Context Window	400k tokens	1M tokens	Gemini 2.5 Pro offers a much larger context window, making it superior for tasks involving massive datasets.
Hallucination Rate	< 1%	Moderate	GPT-5 is noted for its extremely low error and hallucination rates, a key focus of its development.
Multimodality	Text and images	Text, images, audio, video	Both are multimodal, but Gemini 2.5 Pro supports a broader range of input types, including audio and video.