Is GPT-5.3 Instant and GPT-5.4 Content Detectable?

In March 2026, OpenAI released two new models, GPT-5.3 Instant and GPT-5.4.

This follows multiple new AI model releases from leading LLM companies in late 2025, including GPT-5.1, GPT-5.2, Gemini 3, and Grok 4.1 Fast.

Now that GPT-5.3 Instant and GPT-5.4 are here… are they still detectable?

In this study, we analyzed whether content generated by OpenAI’s new GPT-5.3 Instant and GPT-5.4 models is still identified as Likely AI by the industry-leading Originality.ai AI Checker.

Quick Results (TL;DR): Is GPT-5.3 Instant & GPT-5.4 Content Detectable?

Yes, Originality.ai’s AI Detector is highly accurate at detecting GPT-5.3 Instant and GPT-5.4 text across all models:

GPT-5.3 Instant:

• Lite = 99%+ accuracy
• Turbo = 99%+ accuracy
• Academic = 99%+ accuracy

GPT-5.4:

• Lite = 96% accuracy
• Turbo = 97% accuracy
• Academic = 96% accuracy

The GPT-5.3 Instant and GPT-5.4 Detectability Study

As leading LLM companies like OpenAI launch new AI models, it’s essential for AI detectors to continue testing their accuracy.

So, when GPT-5.3 Instant and GPT-5.4 were launched, we tested the accuracy of the Originality.ai AI detection models (Lite, Tubo, and Academic) on both of these new models from OpenAI.

Take a look at an overview of our test below.

GPT-5.3 Instant and GPT-5.4: The Detectability Test 

Although our AI detection models were not trained on GPT-5.3 Instant or GPT-5.4 data, this study assesses their capability to identify text generated by GPT-5.3 Instant and GPT-5.4.

The Dataset (run for both GPT-5.3 Instant and GPT-5.4, respectively):

5,000 high-quality human-written samples spanning:

• Domains/Topics: health, news, finance, technology, arts & entertainment
• Content Types: blogs, reviews, expository articles, conversational text
• Prompt Structures: to maximize stylistic and topical diversity

Then, GPT-5.3 Instant and GPT-5.4 were used to generate completions for each human-written sample prompt. 

This produced a balanced dataset to evaluate the accuracy of Originality.ai’s AI detection capabilities.

The GPT-5.3 Instant and GPT-5.4 Detectability Results

After testing the Originality.ai AI detection models on this dataset, we found that both GPT-5.3 Instant and GPT-5.4 are still detectable by the industry-leading Originality.ai AI detector with a high degree of accuracy.

Accuracy ratings for GPT-5.3 Instant by Originality.ai AI detection models:

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Accuracy ratings for GPT-5.4 by Originality.ai AI detection models:

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Final Thoughts

Although GPT-5.3 Instant and GPT-5.4 didn’t yet exist when the Originality.ai AI detection models were trained, all of the models are showing a strong generalization performance. 

Originality.ai demonstrated an exceptional accuracy of 99%+ for identifying GPT-5.3 Instant text across all models. The Originality.ai AI detector also showed strong performance in detecting GPT-5.4 text across all models, achieving an accuracy of 96-97%.

So, yes — GPT-5.3 Instant and GPT-5.4 are still highly detectable by Originality.ai!

For students, teachers, writers, editors, and more, Originality.ai is still a reliable way to maintain transparency about whether content is Likely AI or human-written.

Try Originality.ai’s AI detector today!

Learn more about AI detection accuracy:

• AI Detection Accuracy Study
• 3rd Party AI Detection Accuracy Studies: Meta-Analysis
• Which AI Detection Model Should I Use?
• Originality.ai’s Academic Model for Students and Teachers

AI studies for recently released models:

• GPT-5.2
• Gemini 3
• GPT-5.1
• Grok 4.1 Fast