Side-by-side benchmark comparison across agentic, coding, multimodal, knowledge, reasoning, and math workflows.
GPT-5.3 Instant and GPT-5.3-Codex-Spark finish on the same overall score, so this is less about a single winner and more about where the edge shows up. The headline says tie; the benchmark table is where the real choice happens.
GPT-5.3 Instant is also the more expensive model on tokens at $1.75 input / $14.00 output per 1M tokens, versus $2.00 input / $8.00 output per 1M tokens for GPT-5.3-Codex-Spark. GPT-5.3-Codex-Spark gives you the larger context window at 256K, compared with 128K for GPT-5.3 Instant.
Treat this as a split decision. GPT-5.3 Instant makes more sense if multimodal & grounded is the priority; GPT-5.3-Codex-Spark is the better fit if coding is the priority or you want the cheaper token bill.
GPT-5.3 Instant
82.9
GPT-5.3-Codex-Spark
85.6
GPT-5.3 Instant
78.7
GPT-5.3-Codex-Spark
82.3
GPT-5.3 Instant
95
GPT-5.3-Codex-Spark
88.3
GPT-5.3 Instant
94.2
GPT-5.3-Codex-Spark
92.7
GPT-5.3 Instant
80.8
GPT-5.3-Codex-Spark
78.3
GPT-5.3 Instant
96
GPT-5.3-Codex-Spark
92
GPT-5.3 Instant
93.4
GPT-5.3-Codex-Spark
90.8
GPT-5.3 Instant
97.2
GPT-5.3-Codex-Spark
96.7
GPT-5.3 Instant and GPT-5.3-Codex-Spark are tied on overall score, so the right pick depends on which category matters most for your use case.
GPT-5.3 Instant has the edge for knowledge tasks in this comparison, averaging 80.8 versus 78.3. Inside this category, FrontierScience is the benchmark that creates the most daylight between them.
GPT-5.3-Codex-Spark has the edge for coding in this comparison, averaging 82.3 versus 78.7. Inside this category, LiveCodeBench is the benchmark that creates the most daylight between them.
GPT-5.3 Instant has the edge for math in this comparison, averaging 97.2 versus 96.7. Inside this category, AIME 2023 is the benchmark that creates the most daylight between them.
GPT-5.3 Instant has the edge for reasoning in this comparison, averaging 94.2 versus 92.7. Inside this category, SimpleQA is the benchmark that creates the most daylight between them.
GPT-5.3-Codex-Spark has the edge for agentic tasks in this comparison, averaging 85.6 versus 82.9. Inside this category, Terminal-Bench 2.0 is the benchmark that creates the most daylight between them.
GPT-5.3 Instant has the edge for multimodal and grounded tasks in this comparison, averaging 95 versus 88.3. Inside this category, MMMU-Pro is the benchmark that creates the most daylight between them.
GPT-5.3 Instant has the edge for instruction following in this comparison, averaging 96 versus 92. Inside this category, IFEval is the benchmark that creates the most daylight between them.
GPT-5.3 Instant has the edge for multilingual tasks in this comparison, averaging 93.4 versus 90.8. Inside this category, MMLU-ProX is the benchmark that creates the most daylight between them.
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