GPT-5.3 Codex
According to BenchLM.ai, GPT-5.3 Codex ranks #7 out of 110 models on the provisional leaderboard with an overall score of 89/100. It does not yet have enough sourced coverage for BenchLM's verified leaderboard. This places it in the upper tier of AI models, with competitive scores across most benchmark categories.
GPT-5.3 Codex is a proprietary model with a 400K token context window. It uses explicit chain-of-thought reasoning, which typically improves performance on math and complex reasoning tasks at the cost of higher latency and token usage.
GPT-5.3 Codex sits inside the GPT-5.3 Codex family alongside GPT-5.3-Codex-Spark. This profile currently has 5 of 152 tracked benchmarks. BenchLM only exposes non-generated benchmark rows publicly, so missing categories stay blank until a sourced evaluation is available.
Its strongest category is Mathematics (#1), while its weakest is Instruction Following (#11). This performance profile makes it particularly strong for mathematical reasoning, scientific computing, and quantitative analysis.
Ranking Distribution
Category rank across 8 benchmark categories — sorted by best rank
Category Performance
Scores across all benchmark categories (0-100 scale)
Category Breakdown
Agentic
#11Coding
#7Reasoning
#2Knowledge
#5Math
#1Multilingual
#5Multimodal
#6Inst. Following
#11Chatbot Arena Performance
Benchmark Details
Only benchmark rows with an attached exact-source record are shown here. Source-unverified manual rows and generated rows are hidden from model pages.
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Frequently Asked Questions
How does GPT-5.3 Codex perform overall in AI benchmarks?
GPT-5.3 Codex currently ranks #7 out of 110 models on BenchLM's provisional leaderboard with an overall score of 89 (estimated). It is created by OpenAI and features a 400K context window.
Is GPT-5.3 Codex good for coding and programming?
GPT-5.3 Codex ranks #7 out of 110 models in coding and programming benchmarks with an average score of 88.5. It is among the top performers in this category.
Is GPT-5.3 Codex good for agentic tool use and computer tasks?
GPT-5.3 Codex ranks #11 out of 110 models in agentic tool use and computer tasks benchmarks with an average score of 83.3. There are stronger options in this category.
Which sibling models are related to GPT-5.3 Codex?
GPT-5.3 Codex belongs to the GPT-5.3 Codex family. Related variants on BenchLM include GPT-5.3-Codex-Spark.
Does GPT-5.3 Codex have full benchmark coverage on BenchLM?
Not yet. GPT-5.3 Codex currently has 5 published benchmark scores out of the 152 benchmarks BenchLM tracks. BenchLM only exposes non-generated public benchmark rows, so missing categories stay blank until a sourced evaluation is available.
What is the context window size of GPT-5.3 Codex?
GPT-5.3 Codex has a context window of 400K, which determines how much text it can process in a single interaction.
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