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GPT 6.1 Sol medium vs Haiku 5.5 low

GPT 6.1 Sol medium leads on quality: 24.0 points higher; Haiku 5.5 low leads on cost and agent time: 4.4× cheaper and 1.2× faster.

24 tasksData from

Stet score

GPT 6.1 Sol mediumRank 2 of 14

65.395% range 55.6–74.624.0 points higher

Haiku 5.5 lowRank 10 of 14

41.395% range 34.8–47.8

Their 95% score ranges don’t overlap.

Cost / task

GPT 6.1 Sol medium$1.10
Haiku 5.5 low$0.254.4× cheaper

Agent time / task

GPT 6.1 Sol medium11.8 min
Haiku 5.5 low9.9 min1.2× faster

Task by task

GPT 6.1 Sol medium solved 3 tasks that Haiku 5.5 low didn’t, and Haiku 5.5 low solved 1 that GPT 6.1 Sol medium didn’t. Both solved 10; neither solved 10.

GPT 6.1 Sol medium only 3

  • stet-6f84e978Equivalent to the merged fix
  • stet-commit-f8ae1177Passed tests
  • stet-commit-342d0ac0Equivalent to the merged fix

Haiku 5.5 low 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 lowSolved 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-15439c21Passed testsEquivalent to the merged fixBoth
stet-66762b4cPassed testsEquivalent to the merged fixBoth
stet-commit-f0caded9FailedEquivalent to the merged fixHaiku 5.5 low only
stet-commit-5d766ddeEquivalent to the merged fixEquivalent to the merged fixBoth
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
Rank2 of 1410 of 14
Stet score65.395% range 55.6–74.641.395% range 34.8–47.8
Solved13/2410 passed, 3 judged equivalent11/247 passed, 4 judged equivalent
Passed review10/248/24
Matched merged change10/249/24
Cost / task$1.10$0.25
How cost was recordedestimated from tokensreported by its harness
Agent time / task11.8 min9.9 min
Ran inDaytona sandboxDaytona sandbox

Where each setup is the better choice

The leaderboard’s readings on groups of tasks. Each group holds fewer tasks than the overall standings, so treat these as leads to test on your repo.

Changes up to 150 lines

11 tasks

11 tasks whose merged change was 2–149 lines in 1–2 files. The 7 small fixes below are among them.

Both matched the merged change on 7 of 11.

GPT 6.1 Sol medium passed review more often: 8 of 11 to Haiku 5.5 low’s 7.

Changes up to 150 lines
GPT 6.1 Sol mediumHaiku 5.5 low
Matched merged change7/117/11
Passed review8/117/11
Cost / task$0.47$0.02
Agent time / task5.8 min2.8 min

Small fixes

7 tasks

7 tasks whose instructions start with “Fix”. Their merged changes were 4–29 lines in 1–2 files.

GPT 6.1 Sol medium matched the merged change more often: 6 of 7 to Haiku 5.5 low’s 5.

Small fixes
GPT 6.1 Sol mediumHaiku 5.5 low
Matched merged change6/75/7
Passed review5/75/7
Cost / task$0.42$0.01
Agent time / task5.3 min2.7 min

Larger changes

13 tasks

13 tasks whose merged change ran over 150 lines or more than 3 files: 113–1,420 lines in 2–19 files.

GPT 6.1 Sol medium matched the merged change more often: 3 of 13 to Haiku 5.5 low’s 2.

Larger changes
GPT 6.1 Sol mediumHaiku 5.5 low
Matched merged change3/132/13
Passed review2/131/13
Cost / task$1.63$0.45
Agent time / task16.9 min15.9 min

From the leaderboard’s routing advice

  • Small fix: to spend less, use GPT 6.1 Sol medium.
  • Larger change: use GPT 6.1 Sol medium.
  • Anything else: use GPT 6.1 Sol medium.
  • Subagents: use Haiku 5.5 low.

See which setup wins on your repo

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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 14 setups: compare-n24-r3b.

See all 14 setups on the leaderboardHow Stet measures