Side-by-side benchmark comparison across agentic, coding, multimodal, knowledge, reasoning, and math workflows.
GPT-5.3 Codex is clearly ahead on the aggregate, 59 to 25. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.
GPT-5.3 Codex's sharpest advantage is in reasoning, where it averages 93.9 against 24.9. The single biggest benchmark swing on the page is SimpleQA, 24.9% to 95%.
GPT-5.3 Codex is also the more expensive model on tokens at $2.50 input / $10.00 output per 1M tokens, versus $0.27 input / $1.10 output per 1M tokens for DeepSeek V3. That is roughly 9.1x on output cost alone. GPT-5.3 Codex is the reasoning model in the pair, while DeepSeek V3 is not. That usually helps on harder chain-of-thought-heavy tests, but it can also mean more latency and more token spend in real use. GPT-5.3 Codex gives you the larger context window at 400K, compared with 128K for DeepSeek V3.
Pick GPT-5.3 Codex if you want the stronger benchmark profile. DeepSeek V3 only becomes the better choice if you want the cheaper token bill or you would rather avoid the extra latency and token burn of a reasoning model.
Comparable scores for this category are coming soon. One or both models do not have sourced results here yet.
DeepSeek V3
42
GPT-5.3 Codex
56.8
Benchmark data for this category is coming soon.
DeepSeek V3
24.9
GPT-5.3 Codex
93.9
DeepSeek V3
69.6
GPT-5.3 Codex
96
Benchmark data for this category is coming soon.
Benchmark data for this category is coming soon.
DeepSeek V3
90.2
GPT-5.3 Codex
96
GPT-5.3 Codex is ahead overall, 59 to 25. The biggest single separator in this matchup is SimpleQA, where the scores are 24.9% and 95%.
GPT-5.3 Codex has the edge for knowledge tasks in this comparison, averaging 96 versus 69.6. Inside this category, GPQA is the benchmark that creates the most daylight between them.
GPT-5.3 Codex has the edge for coding in this comparison, averaging 56.8 versus 42. DeepSeek V3 stays close enough that the answer can still flip depending on your workload.
GPT-5.3 Codex has the edge for math in this comparison, averaging 96 versus 90.2. Inside this category, AIME 2024 is the benchmark that creates the most daylight between them.
GPT-5.3 Codex has the edge for reasoning in this comparison, averaging 93.9 versus 24.9. Inside this category, SimpleQA is the benchmark that creates the most daylight between them.
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