GLM 5.3 Flash high vs GPT 6 Sol medium

No clear quality winner: GPT 6 Sol medium won 16, GLM 5.3 Flash high won 3, 5 tied; GLM 5.3 Flash high leads on cost: 7.3× cheaper; GPT 6 Sol medium leads on agent time: 1.7× faster.

24 tasksData from October 29, 2026

Stet score

GLM 5.3 Flash highcodex · high reasoningRank 15 of 16

29.095% range 19.9–39.3

GPT 6 Sol mediumcodex · medium reasoningRank 9 of 16

55.495% range 47.9–62.726.4 points higher

Other setups

Muse Wonder Full low

70.4

GPT 5.6 Luna max

70.3

SWE-2 Max high

64.3

GPT 6.1 Sol medium

62.5

Opus 5 medium

62.3

Grok 4.7 high

60.7

Pareto 26.9 medium

57.1

Haiku 5.5 max

55.5

GPT 6 Luna max

47.4

DeepSeek V4.1 Flash max

45.9

Opus 4.8 medium

39.2

Haiku 5.5 low

38.9

Muse Spark 1.3 high

31.9

GPT 6 Luna low

19.9

Their 95% score ranges don’t overlap.

Cost / task

GLM 5.3 Flash high$0.417.3× cheaper

GPT 6 Sol medium$3.01

Agent time / task

GLM 5.3 Flash high26.7 min

GPT 6 Sol medium15.4 min1.7× faster

Quality

Head-to-head matchups

GLM 5.3 Flash high won3

Tied5

GPT 6 Sol medium won16

GPT 6 Sol medium’s win share 79%, 95% range 64–92%Ties are within judge noise.

Task by task

GLM 5.3 Flash high solved 0 tasks that GPT 6 Sol medium didn’t, and GPT 6 Sol medium solved 5 that GLM 5.3 Flash high didn’t. Both solved 9; neither solved 10.

GLM 5.3 Flash high only 0

GPT 6 Sol medium only 5

stet-commit-5d766ddeEquivalent to the merged fix
stet-43493c52Passed tests
stet-6f84e978Passed tests
stet-commit-342d0ac0Equivalent to the merged fix
stet-commit-f8ae1177Passed 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
Task	GLM 5.3 Flash high	GPT 6 Sol medium	Solved by
`stet-3169aefa`	Passed tests	Passed tests	Both
`stet-89dfbc27`	Passed tests	Passed tests	Both
`stet-b28f4fe7`	Passed tests	Passed tests	Both
`stet-232b50ba`	Passed tests	Passed tests	Both
`stet-5276aa3f`	Passed tests	Passed tests	Both
`stet-commit-bbbbae09`	Passed tests	Passed tests	Both
`stet-66762b4c`	Passed tests	Passed tests	Both
`stet-15439c21`	Passed tests	Passed tests	Both
`stet-commit-5d766dde`	Failed	Equivalent to the merged fix	GPT 6 Sol medium only
`stet-43493c52`	Failed	Passed tests	GPT 6 Sol medium only
`stet-commit-f0caded9`	Passed tests	Equivalent to the merged fix	Both
`stet-6f84e978`	Failed	Passed tests	GPT 6 Sol medium only
`stet-2450ca2d`	Failed	Failed	Neither
`stet-commit-342d0ac0`	Failed	Equivalent to the merged fix	GPT 6 Sol medium only
`stet-commit-f8ae1177`	Failed	Passed tests	GPT 6 Sol medium only
`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-30506f8e`	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 6 Sol medium
Harness	codex	codex
Reasoning effort	high	medium
Rank	15 of 16	9 of 16
Stet score	29.095% range 19.9–39.3	55.495% range 47.9–62.7
Solved	9/249 passed, 0 judged equivalent	14/2411 passed, 3 judged equivalent
Cost / task	$0.41	$3.01
Agent time / task	26.7 min	15.4 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 October 29, 2026.
Both setups come from the same leaderboard run of 16 setups: bmk_d4ba310fdf50db4ccb2092e3.

See all 16 setups on the leaderboard How Stet measures