Gemini 1.5 Pro vs GPT-3.5 Turbo

Compare Gemini 1.5 Pro by Google AI against GPT-3.5 Turbo by OpenAI, context windows of 1.0M vs 16K, tested across 11 shared challenges. Updated April 2026.

Which is better, Gemini 1.5 Pro or GPT-3.5 Turbo?

Gemini 1.5 Pro and GPT-3.5 Turbo are both competitive models. Gemini 1.5 Pro costs $3.5/M input tokens vs $1.5/M for GPT-3.5 Turbo. Context windows: 1000K vs 16K tokens. Compare their real outputs side by side below.

Key Differences Between Gemini 1.5 Pro and GPT-3.5 Turbo

Gemini 1.5 Pro is made by google while GPT-3.5 Turbo is from openai. Gemini 1.5 Pro has a 1000K token context window compared to GPT-3.5 Turbo's 16K. On pricing, Gemini 1.5 Pro costs $3.5/M input tokens vs $1.5/M for GPT-3.5 Turbo.

Our Verdict
Gemini 1.5 Pro
Gemini 1.5 Pro
GPT-3.5 Turbo
GPT-3.5 TurboRunner-up

No community votes yet. On paper, Gemini 1.5 Pro has the edge — bigger model tier, newer, bigger context window.

GPT-3.5 Turbo is 5.3x cheaper per token — worth considering if cost matters.

Slight edge
Writing DNA

Style Comparison

Similarity
93%

Gemini 1.5 Pro uses 365.8x more bold

Gemini 1.5 Pro
GPT-3.5 Turbo
61%Vocabulary61%
15wSentence Length16w
0.80Hedging0.23
3.7Bold0.0
3.3Lists3.7
0.00Emoji0.00
0.08Headings0.00
0.09Transitions0.38
Based on 8 + 11 text responses
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Ask them anything yourself

Gemini 1.5 ProGPT-3.5 Turbo

Some models write identically. You are paying for the brand.

178 models fingerprinted across 32 writing dimensions. Free research.

Model Similarity Index

185x

price gap between models that write identically

178

models

12

clone pairs

32

dimensions

Devstral M / S
95.7%
Qwen3 Coder / Flash
95.6%
GPT-5.4 / Mini
93.3%

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AI Hallucination Index 2026
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