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GLM 5.3 Flash vs Haiku 5.5 low+guidance

Haiku 5.5 low+guidance leads on quality, cost and agent time: 11.3 points higher, 1.4× cheaper and 2.2× faster.

24 tasksData from

Stet score

GLM 5.3 Flashcodex · high reasoningRank 14 of 15

31.195% range 21.5–41.9

Haiku 5.5 low+guidanceclaude-code · low reasoningRank 10 of 15

42.495% range 33.2–51.711.3 points higher

A directional read: their 95% score ranges overlap.

Cost / task

GLM 5.3 Flash$0.41
Haiku 5.5 low+guidance$0.291.4× cheaper

Agent time / task

GLM 5.3 Flash26.7 min
Haiku 5.5 low+guidance12.4 min2.2× faster

Quality

Head-to-head matchups

GLM 5.3 Flash won4

Tied6

Haiku 5.5 low+guidance won14

Haiku 5.5 low+guidance’s win share 68%, 95% range 52–82%Ties are within judge noise.

Task by task

GLM 5.3 Flash solved 1 task that Haiku 5.5 low+guidance didn’t, and Haiku 5.5 low+guidance solved 1 that GLM 5.3 Flash didn’t. Both solved 8; neither solved 14.

GLM 5.3 Flash only 1

  • stet-15439c21Passed tests

Haiku 5.5 low+guidance only 1

  • stet-43493c52Passed tests

A task counts as solved when its tests passed or a judge found the fix equivalent to the merged change, as in the leaderboard’s Solved column. Stet score also weighs code quality, so it can order the two differently.

All 24 compared tasks
Task by task
TaskGLM 5.3 FlashHaiku 5.5 low+guidanceSolved by
stet-3169aefaPassed testsPassed testsBoth
stet-89dfbc27Passed testsPassed testsBoth
stet-b28f4fe7Passed testsPassed testsBoth
stet-232b50baPassed testsPassed testsBoth
stet-5276aa3fPassed testsPassed testsBoth
stet-commit-bbbbae09Passed testsPassed testsBoth
stet-66762b4cPassed testsPassed testsBoth
stet-15439c21Passed testsFailedGLM 5.3 Flash only
stet-commit-f0caded9Passed testsEquivalent to the merged fixBoth
stet-commit-5d766ddeFailedFailedNeither
stet-43493c52FailedPassed testsHaiku 5.5 low+guidance only
stet-6f84e978FailedFailedNeither
stet-commit-f8ae1177FailedFailedNeither
stet-2450ca2dFailedFailedNeither
stet-commit-342d0ac0FailedFailedNeither
stet-commit-60a0e6c2FailedFailedNeither
stet-commit-5e075641FailedFailedNeither
stet-commit-2826765eFailedFailedNeither
stet-commit-a8716b88FailedFailedNeither
stet-commit-30506f8eFailedFailedNeither
stet-commit-87814583FailedFailedNeither
stet-commit-d2ab0c25FailedFailedNeither
stet-commit-e41c2e2dFailedFailedNeither
stet-commit-e928166fFailedFailedNeither

Side by side

Side by side
MetricGLM 5.3 FlashHaiku 5.5 low+guidance
Harnesscodexclaude-code
Reasoning efforthighlow
Rank14 of 1510 of 15
Stet score31.195% range 21.5–41.942.495% range 33.2–51.7
Solved9/249 passed, 0 judged equivalent9/248 passed, 1 judged equivalent
Cost / task$0.41$0.29
Agent time / task26.7 min12.4 min

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About this data

  • 24 tasks, each a merged change replayed from the repo as it was just before the merge.
  • Data from .
  • Both setups come from the same leaderboard run of 15 setups: bmk_d4ba310fdf50db4ccb2092e3.

See all 15 setups on the leaderboardHow Stet measures