GPT-4.5 vs GPT-5 Pro
Compare GPT-4.5 and GPT-5 Pro, both from OpenAI, context windows of 128K vs 400K, tested across 17 shared challenges. Updated May 2026.
Which is better, GPT-4.5 or GPT-5 Pro?
GPT-4.5 and GPT-5 Pro are both competitive models. GPT-4.5 costs $75/M input tokens vs $15/M for GPT-5 Pro. Context windows: 128K vs 400K tokens. Compare their real outputs side by side below.
Key Differences Between GPT-4.5 and GPT-5 Pro
GPT-4.5 is made by openai while GPT-5 Pro is from openai. GPT-4.5 has a 128K token context window compared to GPT-5 Pro's 400K. On pricing, GPT-4.5 costs $75/M input tokens vs $15/M for GPT-5 Pro.
API pricing
Per 1M tokens
GPT-4.5
Input
$75.00
Output
$150.00
GPT-5 Pro
Input
$15.00
5.0× cheaper
Output
$120.00
1.3× cheaper
GPT-5 Pro is cheaper on both — 5.0× input, 1.3× output
Our Verdict
GPT-5 Pro
GPT-4.5Runner-up
No community votes yet. On paper, GPT-5 Pro has the edge — newer, bigger context window.
Too close to call
Writing DNA
Style Comparison
Similarity
43%
GPT-4.5 uses 466.6x more bold
GPT-4.5
GPT-5 Pro
63%Vocabulary65%
16wSentence Length15w
0.57Hedging0.32
4.7Bold0.0
6.4Lists2.9
0.00Emoji0.00
1.30Headings0.00
0.54Transitions0.01
Based on 11 + 11 text responses
FAQ
