GPT-5.3 Instant vs GPT-5.1

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 80. 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 66.2. The single biggest benchmark swing on the page is HLE, 44 to 27.

GPT-5.3 Instant is also the more expensive model on tokens at $1.75 input / $14.00 output per 1M tokens, versus $1.50 input / $6.00 output per 1M tokens for GPT-5.1. That is roughly 2.3x on output cost alone. GPT-5.1 gives you the larger context window at 200K, compared with 128K for GPT-5.3 Instant.

Quick Verdict

Pick GPT-5.3 Instant if you want the stronger benchmark profile. GPT-5.1 only becomes the better choice if you want the cheaper token bill or you need the larger 200K context window.

Agentic

GPT-5.3 Instant

GPT-5.3 Instant

82.9

GPT-5.1

75.8

86
Terminal-Bench 2.0
78
82
BrowseComp
79
80
OSWorld-Verified
71

Coding

GPT-5.3 Instant

GPT-5.3 Instant

78.7

GPT-5.1

66.2

88
HumanEval
89
76
SWE-bench Verified
68
75
LiveCodeBench
61
83
SWE-bench Pro
71

Multimodal & Grounded

GPT-5.3 Instant

GPT-5.3 Instant

95

GPT-5.1

91.8

95
MMMU-Pro
94
95
OfficeQA Pro
89

Reasoning

GPT-5.3 Instant

GPT-5.3 Instant

94.2

GPT-5.1

88.4

96
SimpleQA
93
94
MuSR
91
97
BBH
92
92
LongBench v2
84
94
MRCRv2
84

Knowledge

GPT-5.3 Instant

GPT-5.3 Instant

80.8

GPT-5.1

72.5

99
MMLU
97
98
GPQA
95
96
SuperGPQA
93
94
OpenBookQA
91
89
MMLU-Pro
83
44
HLE
27
92
FrontierScience
84

Instruction Following

GPT-5.3 Instant

GPT-5.3 Instant

96

GPT-5.1

89

96
IFEval
89

Multilingual

GPT-5.3 Instant

GPT-5.3 Instant

93.4

GPT-5.1

87.7

96
MGSM
89
92
MMLU-ProX
87

Mathematics

GPT-5.3 Instant

GPT-5.3 Instant

97.2

GPT-5.1

95.4

99
AIME 2023
99
99
AIME 2024
99
98
AIME 2025
98
95
HMMT Feb 2023
95
97
HMMT Feb 2024
97
96
HMMT Feb 2025
96
96
BRUMO 2025
96
98
MATH-500
94

Frequently Asked Questions

Which is better, GPT-5.3 Instant or GPT-5.1?

GPT-5.3 Instant is ahead overall, 87 to 80. 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-5.1?

GPT-5.3 Instant has the edge for knowledge tasks in this comparison, averaging 80.8 versus 72.5. 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-5.1?

GPT-5.3 Instant has the edge for coding in this comparison, averaging 78.7 versus 66.2. 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-5.1?

GPT-5.3 Instant has the edge for math in this comparison, averaging 97.2 versus 95.4. Inside this category, MATH-500 is the benchmark that creates the most daylight between them.

Which is better for reasoning, GPT-5.3 Instant or GPT-5.1?

GPT-5.3 Instant has the edge for reasoning in this comparison, averaging 94.2 versus 88.4. 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-5.1?

GPT-5.3 Instant has the edge for agentic tasks in this comparison, averaging 82.9 versus 75.8. Inside this category, OSWorld-Verified is the benchmark that creates the most daylight between them.

Which is better for multimodal and grounded tasks, GPT-5.3 Instant or GPT-5.1?

GPT-5.3 Instant has the edge for multimodal and grounded tasks in this comparison, averaging 95 versus 91.8. 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-5.1?

GPT-5.3 Instant has the edge for instruction following in this comparison, averaging 96 versus 89. 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-5.1?

GPT-5.3 Instant has the edge for multilingual tasks in this comparison, averaging 93.4 versus 87.7. Inside this category, MGSM is the benchmark that creates the most daylight between them.

Last updated: March 12, 2026

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