Skip to the comparison
STET
Join the waitlist

GPT 6 Sol medium vs Opus 4.8 medium

No clear quality winner: GPT 6 Sol medium won 13, Opus 4.8 medium won 3, 8 tied; GPT 6 Sol medium leads on cost and agent time: 2.3× cheaper and 1.5× faster.

24 tasksData from

Stet score

GPT 6 Sol mediumcodex · medium reasoningRank 8 of 15

57.095% range 49.2–64.717.2 points higher

Opus 4.8 mediumclaude-code · medium reasoningRank 12 of 15

39.895% range 29.7–50.2

A directional read: their 95% score ranges overlap.

Cost / task

GPT 6 Sol medium$3.012.3× cheaper
Opus 4.8 medium$7.05

Agent time / task

GPT 6 Sol medium15.4 min1.5× faster
Opus 4.8 medium23.3 min

Quality

Head-to-head matchups

GPT 6 Sol medium won13

Tied8

Opus 4.8 medium won3

GPT 6 Sol medium’s win share 66%, 95% range 51–80%Ties are within judge noise.

Task by task

GPT 6 Sol medium solved 2 tasks that Opus 4.8 medium didn’t, and Opus 4.8 medium solved 1 that GPT 6 Sol medium didn’t. Both solved 12; neither solved 9.

GPT 6 Sol medium only 2

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

Opus 4.8 medium only 1

  • stet-commit-60a0e6c2Passed 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
TaskGPT 6 Sol mediumOpus 4.8 mediumSolved 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 testsPassed testsBoth
stet-66762b4cPassed testsPassed testsBoth
stet-commit-5d766ddeEquivalent to the merged fixEquivalent to the merged fixBoth
stet-commit-f0caded9Equivalent to the merged fixEquivalent to the merged fixBoth
stet-43493c52Passed testsPassed testsBoth
stet-6f84e978Passed testsPassed testsBoth
stet-2450ca2dFailedFailedNeither
stet-commit-f8ae1177Passed testsFailedGPT 6 Sol medium only
stet-commit-342d0ac0Equivalent to the merged fixFailedGPT 6 Sol medium only
stet-commit-60a0e6c2FailedPassed testsOpus 4.8 medium only
stet-commit-5e075641FailedFailedNeither
stet-commit-2826765eFailedFailedNeither
stet-commit-a8716b88FailedFailedNeither
stet-commit-e928166fFailedFailedNeither
stet-commit-30506f8eFailedFailedNeither
stet-commit-87814583FailedFailedNeither
stet-commit-d2ab0c25FailedFailedNeither
stet-commit-e41c2e2dFailedFailedNeither

Side by side

Side by side
MetricGPT 6 Sol mediumOpus 4.8 medium
Harnesscodexclaude-code
Reasoning effortmediummedium
Rank8 of 1512 of 15
Stet score57.095% range 49.2–64.739.895% range 29.7–50.2
Solved14/2411 passed, 3 judged equivalent13/2411 passed, 2 judged equivalent
Cost / task$3.01$7.05
Agent time / task15.4 min23.3 min

See which setup wins on your repo

Stet replays your merged PRs, scores quality above pass/fail, and delivers comparison reports through your agent.

Run it on your repo

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