Claude Haiku 4.5 vs o3-mini

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

Claude Haiku 4.5 is clearly ahead on the aggregate, 64 to 56. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.

o3-mini is also the more expensive model on tokens at $1.10 input / $4.40 output per 1M tokens, versus $0.80 input / $4.00 output per 1M tokens for Claude Haiku 4.5. o3-mini is the reasoning model in the pair, while Claude Haiku 4.5 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 Claude Haiku 4.5 if you want the stronger benchmark profile. o3-mini only becomes the better choice if knowledge is the priority or you want the stronger reasoning-first profile.

Knowledge

o3-mini

Claude Haiku 4.5

57.8

o3-mini

82.1

68
MMLU
86.9
67
GPQA
77.2
65
SuperGPQA
-
63
OpenBookQA
-
73
MMLU-Pro
-
11
HLE
-

Coding

o3-mini

Claude Haiku 4.5

48

o3-mini

49.3

60
HumanEval
-
48
SWE-bench Verified
49.3
36
LiveCodeBench
-

Mathematics

o3-mini

Claude Haiku 4.5

68.8

o3-mini

87.3

68
AIME 2023
-
70
AIME 2024
87.3
69
AIME 2025
-
64
HMMT Feb 2023
-
66
HMMT Feb 2024
-
65
HMMT Feb 2025
-
67
BRUMO 2025
-
81
MATH-500
-

Reasoning

Claude Haiku 4.5
65
SimpleQA
-
63
MuSR
-
81
BBH
-

Instruction Following

o3-mini

Claude Haiku 4.5

86

o3-mini

93.9

86
IFEval
93.9

Multilingual

Claude Haiku 4.5
82
MGSM
-

Frequently Asked Questions

Which is better, Claude Haiku 4.5 or o3-mini?

Claude Haiku 4.5 is ahead overall, 64 to 56. The biggest single separator in this matchup is MMLU, where the scores are 68 and 86.9.

Which is better for knowledge tasks, Claude Haiku 4.5 or o3-mini?

o3-mini has the edge for knowledge tasks in this comparison, averaging 82.1 versus 57.8. Inside this category, MMLU is the benchmark that creates the most daylight between them.

Which is better for coding, Claude Haiku 4.5 or o3-mini?

o3-mini has the edge for coding in this comparison, averaging 49.3 versus 48. Inside this category, SWE-bench Verified is the benchmark that creates the most daylight between them.

Which is better for math, Claude Haiku 4.5 or o3-mini?

o3-mini has the edge for math in this comparison, averaging 87.3 versus 68.8. Inside this category, AIME 2024 is the benchmark that creates the most daylight between them.

Which is better for instruction following, Claude Haiku 4.5 or o3-mini?

o3-mini has the edge for instruction following in this comparison, averaging 93.9 versus 86. Inside this category, IFEval is the benchmark that creates the most daylight between them.

Last updated: March 9, 2026

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