GPT-5.3 Instant vs GPT-5 (medium)

Side-by-side benchmark comparison across agentic, coding, multimodal, knowledge, reasoning, and math workflows.

GPT-5.3 Instant is clearly ahead on the aggregate, 87 to 78. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.

GPT-5.3 Instant's sharpest advantage is in coding, where it averages 78.7 against 66.1. The single biggest benchmark swing on the page is HLE, 44 to 27.

Quick Verdict

Pick GPT-5.3 Instant if you want the stronger benchmark profile. GPT-5 (medium) only becomes the better choice if its workflow or ecosystem matters more than the raw scoreboard.

Agentic

GPT-5.3 Instant

GPT-5.3 Instant

82.9

GPT-5 (medium)

75.5

86
Terminal-Bench 2.0
77
82
BrowseComp
78
80
OSWorld-Verified
72

Coding

GPT-5.3 Instant

GPT-5.3 Instant

78.7

GPT-5 (medium)

66.1

88
HumanEval
83
76
SWE-bench Verified
67
75
LiveCodeBench
60
83
SWE-bench Pro
72

Multimodal & Grounded

GPT-5.3 Instant

GPT-5.3 Instant

95

GPT-5 (medium)

88.1

95
MMMU-Pro
89
95
OfficeQA Pro
87

Reasoning

GPT-5.3 Instant

GPT-5.3 Instant

94.2

GPT-5 (medium)

84.3

96
SimpleQA
87
94
MuSR
85
97
BBH
92
92
LongBench v2
81
94
MRCRv2
81

Knowledge

GPT-5.3 Instant

GPT-5.3 Instant

80.8

GPT-5 (medium)

69.8

99
MMLU
91
98
GPQA
89
96
SuperGPQA
87
94
OpenBookQA
85
89
MMLU-Pro
81
44
HLE
27
92
FrontierScience
82

Instruction Following

GPT-5.3 Instant

GPT-5.3 Instant

96

GPT-5 (medium)

88

96
IFEval
88

Multilingual

GPT-5.3 Instant

GPT-5.3 Instant

93.4

GPT-5 (medium)

88.1

96
MGSM
90
92
MMLU-ProX
87

Mathematics

GPT-5.3 Instant

GPT-5.3 Instant

97.2

GPT-5 (medium)

92

99
AIME 2023
93
99
AIME 2024
95
98
AIME 2025
94
95
HMMT Feb 2023
89
97
HMMT Feb 2024
91
96
HMMT Feb 2025
90
96
BRUMO 2025
92
98
MATH-500
92

Frequently Asked Questions

Which is better, GPT-5.3 Instant or GPT-5 (medium)?

GPT-5.3 Instant is ahead overall, 87 to 78. The biggest single separator in this matchup is HLE, where the scores are 44 and 27.

Which is better for knowledge tasks, GPT-5.3 Instant or GPT-5 (medium)?

GPT-5.3 Instant has the edge for knowledge tasks in this comparison, averaging 80.8 versus 69.8. Inside this category, HLE is the benchmark that creates the most daylight between them.

Which is better for coding, GPT-5.3 Instant or GPT-5 (medium)?

GPT-5.3 Instant has the edge for coding in this comparison, averaging 78.7 versus 66.1. Inside this category, LiveCodeBench is the benchmark that creates the most daylight between them.

Which is better for math, GPT-5.3 Instant or GPT-5 (medium)?

GPT-5.3 Instant has the edge for math in this comparison, averaging 97.2 versus 92. Inside this category, AIME 2023 is the benchmark that creates the most daylight between them.

Which is better for reasoning, GPT-5.3 Instant or GPT-5 (medium)?

GPT-5.3 Instant has the edge for reasoning in this comparison, averaging 94.2 versus 84.3. Inside this category, MRCRv2 is the benchmark that creates the most daylight between them.

Which is better for agentic tasks, GPT-5.3 Instant or GPT-5 (medium)?

GPT-5.3 Instant has the edge for agentic tasks in this comparison, averaging 82.9 versus 75.5. Inside this category, Terminal-Bench 2.0 is the benchmark that creates the most daylight between them.

Which is better for multimodal and grounded tasks, GPT-5.3 Instant or GPT-5 (medium)?

GPT-5.3 Instant has the edge for multimodal and grounded tasks in this comparison, averaging 95 versus 88.1. Inside this category, OfficeQA Pro is the benchmark that creates the most daylight between them.

Which is better for instruction following, GPT-5.3 Instant or GPT-5 (medium)?

GPT-5.3 Instant has the edge for instruction following in this comparison, averaging 96 versus 88. Inside this category, IFEval is the benchmark that creates the most daylight between them.

Which is better for multilingual tasks, GPT-5.3 Instant or GPT-5 (medium)?

GPT-5.3 Instant has the edge for multilingual tasks in this comparison, averaging 93.4 versus 88.1. Inside this category, MGSM is the benchmark that creates the most daylight between them.

Last updated: March 12, 2026

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