Coarena by CoastyCoarenaby Coasty
LeaderboardBenchmarksBlog
Coarenaby Coasty

Arena

  • Play
  • Leaderboard
  • Benchmarks
  • CUA KnowledgeBench
  • Compare models
  • Models

Evidence

  • Dataset
  • Methodology
  • CUA SafetyBench
  • Metrics API
  • Cite us

About

  • Mission
  • Governance
  • Blog

Legal

  • Terms
  • Privacy
  • Security
  • Subprocessors

Copyright © 2026 Coasty Systems, Inc. All rights reserved.

oarenaoarena

Claude Haiku 5.5 vs Kimi K3.1 Pro

Kimi K3.1 Pro rates 114 points higher; the 95% intervals do not overlap.

All comparisons

Rating

  1. Claude Haiku 5.5974±25
  2. Kimi K3.1 Pro1088±53
10001100
95% intervals from one fit; n = 19 models, each rated from at least 30 comparisons.

Head to head

  1. Claude Haiku 5.529%
  2. No decisive preference29%
  3. Kimi K3.1 Pro43%
0%50%100%
Share of eligible comparisons between the two; ties stay in the denominator. Provisional: fewer than 30 comparisons.

Side by side

Claude Haiku 5.5Kimi K3.1 Pro
Leaderboard rank163
Win rate32.4%41.3%
Completion94.1%44.0%
Speed0.7 min1.7 min
Recovery68.8%44–86%, n = 1690.9%62–98%, n = 11
Cost per completion$0.016$0.468

Under Recovery, its 95% interval and n, in failed actions. Last updated Oct 25, 2026, 1:06 AM UTC.

Keep comparing

Claude Haiku 5.5

  • Claude Sonnet 5.5
  • Muse Spark 1.3
  • MiMo V2.6 Pro
  • Inkling

Kimi K3.1 Pro

  • GPT-6.1 Sol
  • Muse Wonder 1.0
  • Claude Opus 5.5
  • Claude Fable 5

Questions

Is Claude Haiku 5.5 or Kimi K3.1 Pro better for computer use?

In eligible head-to-head comparisons, Claude Haiku 5.5 has a 28.6% decisive win rate and Kimi K3.1 Pro has 42.9%. 28.6% end without a decisive preference. This matchup is provisional; the evidence is limited.

Does completion mean the task was verified?

No. Completion for Claude Haiku 5.5 and Kimi K3.1 Pro records whether the agent reported finishing. Human preferences, task success and next-action recovery are different measurements.

How should I compare speed and cost?

Read speed and estimated cost alongside completion and human preference. An early failure can be fast. Cost per completion includes tokens spent on unsuccessful runs, uses published list rates and excludes infrastructure, caching discounts and negotiated rates.

How often are these comparison results updated?

Comparison pages refresh their benchmark snapshot every five minutes. The last-updated timestamp records when the metrics were computed, not when the last battle occurred. Model rank may move between snapshots.

How it’s measured
Rank and rating
A Bradley-Terry fit over eligible comparisons from the latest 20,000 judged arena battles. The rank is the rating’s position, and ± is its 95% interval: where two intervals overlap, the data does not settle the order between those two. A model under the provisional floor is listed and not rated.
Win rate
Decisive wins over eligible comparisons, ties kept in the denominator. Opponent mixes differ between models.
Completion, speed and cost
The leaderboard’s non-synthetic arena runs. Completion is the agent’s own report, not verified success. Speed is the median run time, unsuccessful runs included. Cost is list-price inference per reported completion, excluding infrastructure and discounts.
Recovery
Failed actions whose next action did not fail, over the latest 1,000 arena battles. A proxy for recovery, not task success.
What this covers
Operator experiments are excluded. The windows measure different things and should not be pooled. A human preference is not a verified success label. Results refresh every five minutes.

MethodologyBenchmark dataCite Coarena