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GLM 5.3 Flash high vs GPT 5.6 Luna low

GPT 5.6 Luna low leads on speed and cost; quality is too close to call.

Quality
+3.3 pts
GLM 5.3 Flash high
4–1 head to head, 15 tied
Speed
4.0× faster
GPT 5.6 Luna low
6.7 min vs 26.6 min per task
Cost
8.8× cheaper
GPT 5.6 Luna low
$0.05 vs $0.45 per task

24 tasksData from

Stet score

GLM 5.3 Flash highhigh reasoningRank 11 of 17

48.395% range 41.5–55.33.3 points higher

GPT 5.6 Luna lowcodex · low reasoningRank 15 of 17

45.095% range 39.1–50.4

A directional read: their 95% score ranges overlap.

Quality

Head-to-head matchups

GLM 5.3 Flash high won4

Tied15

GPT 5.6 Luna low won1

4 undecided
GLM 5.3 Flash high’s win share 57%, 95% range 46–69%Ties are within judge noise.

Task by task

GLM 5.3 Flash high solved 2 tasks that GPT 5.6 Luna low didn’t, and GPT 5.6 Luna low solved 1 that GLM 5.3 Flash high didn’t. Both solved 8; neither solved 9.

stet-commit-bbbbae09Solved by 15 of 17 setups

  • GLM 5.3 Flash highPassed tests
  • GPT 5.6 Luna lowFailed

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. 4 of the 24 tasks are left out because one of the two has no scored result on them.

All 20 compared tasks
Task by task
TaskGLM 5.3 Flash highGPT 5.6 Luna lowSolved by
stet-232b50baPassed testsPassed testsBoth
stet-3169aefaPassed testsPassed testsBoth
stet-5276aa3fPassed testsPassed testsBoth
stet-89dfbc27Passed testsPassed testsBoth
stet-b28f4fe7Passed testsPassed testsBoth
stet-commit-bbbbae09Passed testsFailedGLM 5.3 Flash high only
stet-66762b4cPassed testsEquivalent to the merged fixBoth
stet-commit-f0caded9Passed testsEquivalent to the merged fixBoth
stet-43493c52FailedPassed testsGPT 5.6 Luna low only
stet-commit-f8ae1177Passed testsFailedGLM 5.3 Flash high only
stet-15439c21Equivalent to the merged fixEquivalent to the merged fixBoth
stet-commit-342d0ac0FailedFailedNeither
stet-commit-60a0e6c2FailedFailedNeither
stet-commit-5e075641FailedFailedNeither
stet-commit-2826765eFailedFailedNeither
stet-commit-a8716b88FailedFailedNeither
stet-commit-e928166fFailedFailedNeither
stet-commit-87814583FailedFailedNeither
stet-commit-d2ab0c25FailedFailedNeither
stet-commit-e41c2e2dFailedFailedNeither

Side by side

Side by side
MetricGLM 5.3 Flash highGPT 5.6 Luna low
Harness—codex
Reasoning efforthighlow
Rank11 of 1715 of 17
Stet score48.395% range 41.5–55.345.095% range 39.1–50.4
Solved10/249 passed, 1 judged equivalent10/246 passed, 4 judged equivalent
Cost / task$0.45from 20/24 tasks$0.05
Agent time / task26.6 minfrom 20/24 tasks6.7 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 17 setups: bmk_d4ba310fdf50db4ccb2092e3.

See all 17 setups on the leaderboardHow Stet measures