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GPT 6.1 Sol medium vs Haiku 5.5 low+guidance

GPT 6.1 Sol medium leads on quality and agent time: 23.4 points higher and 1.1× faster; Haiku 5.5 low+guidance leads on cost: 3.8× cheaper.

24 tasksData from

Stet score

GPT 6.1 Sol mediumcodex · medium reasoningRank 2 of 15

65.895% range 56.0–75.123.4 points higher

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

42.495% range 33.2–51.7

Their 95% score ranges don’t overlap.

Cost / task

GPT 6.1 Sol medium$1.10
Haiku 5.5 low+guidance$0.293.8× cheaper

Agent time / task

GPT 6.1 Sol medium11.8 min1.1× faster
Haiku 5.5 low+guidance12.4 min

Quality

Head-to-head matchups

GPT 6.1 Sol medium won13

Tied9

Haiku 5.5 low+guidance won2

GPT 6.1 Sol medium’s win share 73%, 95% range 59–85%Ties are within judge noise.

Task by task

GPT 6.1 Sol medium solved 5 tasks that Haiku 5.5 low+guidance didn’t, and Haiku 5.5 low+guidance solved 1 that GPT 6.1 Sol medium didn’t. Both solved 8; neither solved 10.

GPT 6.1 Sol medium only 5

  • stet-15439c21Passed tests
  • stet-commit-5d766ddeEquivalent to the merged fix
  • stet-6f84e978Equivalent to the merged fix
  • stet-commit-f8ae1177Passed tests
  • stet-commit-342d0ac0Equivalent to the merged fix

Haiku 5.5 low+guidance only 1

  • stet-commit-f0caded9Equivalent to the merged fix

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
TaskGPT 6.1 Sol mediumHaiku 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 testsFailedGPT 6.1 Sol medium only
stet-commit-f0caded9FailedEquivalent to the merged fixHaiku 5.5 low+guidance only
stet-commit-5d766ddeEquivalent to the merged fixFailedGPT 6.1 Sol medium only
stet-43493c52Passed testsPassed testsBoth
stet-6f84e978Equivalent to the merged fixFailedGPT 6.1 Sol medium only
stet-commit-f8ae1177Passed testsFailedGPT 6.1 Sol medium only
stet-2450ca2dFailedFailedNeither
stet-commit-342d0ac0Equivalent to the merged fixFailedGPT 6.1 Sol medium only
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
MetricGPT 6.1 Sol mediumHaiku 5.5 low+guidance
Harnesscodexclaude-code
Reasoning effortmediumlow
Rank2 of 1510 of 15
Stet score65.895% range 56.0–75.142.495% range 33.2–51.7
Solved13/2410 passed, 3 judged equivalent9/248 passed, 1 judged equivalent
Cost / task$1.10$0.29
Agent time / task11.8 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