GLM 5.3 Flash high vs GPT 5.6 Luna max

GLM 5.3 Flash high leads on speed and cost; quality is too close to call.

Quality: Even; GLM 5.3 Flash high; 3–2 head to head, 15 tied
Speed: 1.1× faster; GLM 5.3 Flash high; 26.6 min vs 28.5 min per task
Cost: 2.0× cheaper; GLM 5.3 Flash high; $0.45 vs $0.90 per task

24 tasksData from November 6, 2026

Stet score

GLM 5.3 Flash highhigh reasoningRank 11 of 17

48.395% range 41.5–55.3

GPT 5.6 Luna maxmax reasoningRank 9 of 17

49.995% range 44.5–55.61.6 points higher

Other setups

SWE-2 Max high

58.4

Opus 5 medium

58.1

Pareto 26.9 medium

55.0

GPT 6.1 Sol medium

54.1

GPT 6 Sol medium

53.2

Grok 4.7 high

52.9

Muse Wonder Full low

52.1

DeepSeek V4.1 Flash max

50.6

Haiku 5.5 max

48.8

Opus 4.8 medium

47.0

GPT 6 Luna max

46.5

Haiku 5.5 low

45.1

GPT 5.6 Luna low

45.0

GPT 6 Luna low

40.3

Muse Spark 1.3 high

47.8

A directional read: their 95% score ranges overlap.

Quality

Head-to-head matchups

GLM 5.3 Flash high won3

Tied15

GPT 5.6 Luna max won2

4 undecided

GLM 5.3 Flash high’s win share 51%, 95% range 39–62%Ties are within judge noise.

Task by task

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

stet-43493c52Solved by 11 of 17 setups

GLM 5.3 Flash highFailed
GPT 5.6 Luna maxPassed 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. 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
Task	GLM 5.3 Flash high	GPT 5.6 Luna max	Solved by
`stet-232b50ba`	Passed tests	Passed tests	Both
`stet-3169aefa`	Passed tests	Passed tests	Both
`stet-5276aa3f`	Passed tests	Passed tests	Both
`stet-89dfbc27`	Passed tests	Passed tests	Both
`stet-b28f4fe7`	Passed tests	Passed tests	Both
`stet-commit-bbbbae09`	Passed tests	Passed tests	Both
`stet-66762b4c`	Passed tests	Equivalent to the merged fix	Both
`stet-commit-f0caded9`	Passed tests	Equivalent to the merged fix	Both
`stet-43493c52`	Failed	Passed tests	GPT 5.6 Luna max only
`stet-commit-f8ae1177`	Passed tests	Failed	GLM 5.3 Flash high only
`stet-15439c21`	Equivalent to the merged fix	Failed	GLM 5.3 Flash high only
`stet-commit-342d0ac0`	Failed	Failed	Neither
`stet-commit-60a0e6c2`	Failed	Failed	Neither
`stet-commit-5e075641`	Failed	Failed	Neither
`stet-commit-2826765e`	Failed	Failed	Neither
`stet-commit-a8716b88`	Failed	Failed	Neither
`stet-commit-e928166f`	Failed	Failed	Neither
`stet-commit-87814583`	Failed	Failed	Neither
`stet-commit-d2ab0c25`	Failed	Failed	Neither
`stet-commit-e41c2e2d`	Failed	Failed	Neither

Side by side

Side by side
Metric	GLM 5.3 Flash high	GPT 5.6 Luna max
Reasoning effort	high	max
Rank	11 of 17	9 of 17
Stet score	48.395% range 41.5–55.3	49.995% range 44.5–55.6
Solved	10/249 passed, 1 judged equivalent	10/247 passed, 3 judged equivalent
Cost / task	$0.45from 20/24 tasks	$0.90
Agent time / task	26.6 minfrom 20/24 tasks	28.5 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 November 6, 2026.
Both setups come from the same leaderboard run of 17 setups: bmk_d4ba310fdf50db4ccb2092e3.

See all 17 setups on the leaderboard How Stet measures