GPT-5.3 Instant vs Z-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 47. 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 26.7. The single biggest benchmark swing on the page is LiveCodeBench, 75 to 22.

GPT-5.3 Instant is the reasoning model in the pair, while Z-1 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.

Quick Verdict

Pick GPT-5.3 Instant if you want the stronger benchmark profile. Z-1 only becomes the better choice if you would rather avoid the extra latency and token burn of a reasoning model.

Agentic

GPT-5.3 Instant

GPT-5.3 Instant

82.9

Z-1

42.2

86
Terminal-Bench 2.0
39
82
BrowseComp
49
80
OSWorld-Verified
41

Coding

GPT-5.3 Instant

GPT-5.3 Instant

78.7

Z-1

26.7

88
HumanEval
44
76
SWE-bench Verified
33
75
LiveCodeBench
22
83
SWE-bench Pro
30

Multimodal & Grounded

GPT-5.3 Instant

GPT-5.3 Instant

95

Z-1

50.5

95
MMMU-Pro
46
95
OfficeQA Pro
56

Reasoning

GPT-5.3 Instant

GPT-5.3 Instant

94.2

Z-1

54.8

96
SimpleQA
50
94
MuSR
48
97
BBH
74
92
LongBench v2
56
94
MRCRv2
57

Knowledge

GPT-5.3 Instant

GPT-5.3 Instant

80.8

Z-1

42.7

99
MMLU
52
98
GPQA
51
96
SuperGPQA
49
94
OpenBookQA
47
89
MMLU-Pro
64
44
HLE
6
92
FrontierScience
51

Instruction Following

GPT-5.3 Instant

GPT-5.3 Instant

96

Z-1

80

96
IFEval
80

Multilingual

GPT-5.3 Instant

GPT-5.3 Instant

93.4

Z-1

72.7

96
MGSM
74
92
MMLU-ProX
72

Mathematics

GPT-5.3 Instant

GPT-5.3 Instant

97.2

Z-1

60.9

99
AIME 2023
52
99
AIME 2024
54
98
AIME 2025
53
95
HMMT Feb 2023
48
97
HMMT Feb 2024
50
96
HMMT Feb 2025
49
96
BRUMO 2025
51
98
MATH-500
73

Frequently Asked Questions

Which is better, GPT-5.3 Instant or Z-1?

GPT-5.3 Instant is ahead overall, 87 to 47. The biggest single separator in this matchup is LiveCodeBench, where the scores are 75 and 22.

Which is better for knowledge tasks, GPT-5.3 Instant or Z-1?

GPT-5.3 Instant has the edge for knowledge tasks in this comparison, averaging 80.8 versus 42.7. Inside this category, MMLU is the benchmark that creates the most daylight between them.

Which is better for coding, GPT-5.3 Instant or Z-1?

GPT-5.3 Instant has the edge for coding in this comparison, averaging 78.7 versus 26.7. Inside this category, LiveCodeBench is the benchmark that creates the most daylight between them.

Which is better for math, GPT-5.3 Instant or Z-1?

GPT-5.3 Instant has the edge for math in this comparison, averaging 97.2 versus 60.9. 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 Z-1?

GPT-5.3 Instant has the edge for reasoning in this comparison, averaging 94.2 versus 54.8. Inside this category, SimpleQA is the benchmark that creates the most daylight between them.

Which is better for agentic tasks, GPT-5.3 Instant or Z-1?

GPT-5.3 Instant has the edge for agentic tasks in this comparison, averaging 82.9 versus 42.2. 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 Z-1?

GPT-5.3 Instant has the edge for multimodal and grounded tasks in this comparison, averaging 95 versus 50.5. Inside this category, MMMU-Pro is the benchmark that creates the most daylight between them.

Which is better for instruction following, GPT-5.3 Instant or Z-1?

GPT-5.3 Instant has the edge for instruction following in this comparison, averaging 96 versus 80. 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 Z-1?

GPT-5.3 Instant has the edge for multilingual tasks in this comparison, averaging 93.4 versus 72.7. Inside this category, MGSM is the benchmark that creates the most daylight between them.

Last updated: March 12, 2026

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