Claude Opus 5.5 vs Kimi K3 256K
Claude Opus 5.5 leads overall, B- to D+. Claude Opus 5.5 is about 6.0x cheaper per task. By suite, Claude Opus 5.5 takes real-world issues (C+ to C-) and spec planning (C+ to C-). The data gives no reason to pick Kimi K3 256K over Claude Opus 5.5 this week.Measured
Each agent graded on the same private suites, running headless through its own tools. Advantages are oriented so a win is a win, whichever way the metric runs.
Verdict: Kimi K3 256K vs Claude Opus 5.5
Claude Opus 5.5 leads overall, B- to D+. By suite: Claude Opus 5.5 takes real-world issues, C+ to C- (73% vs 60% capability); Claude Opus 5.5 takes spec planning, C+ to C- (73% vs 56% capability); Claude Opus 5.5 takes vibe coding, B+ to F (90% vs 34% capability). Claude Opus 5.5 used 2% of Claude Max 5x's weekly limit per pass, $0.024 per task at the listed price. Kimi K3 256K used 31% of Kimi Allegretto's weekly limit per pass, $0.146 per task at the listed price. Per task, Claude Opus 5.5 is about 6.0x cheaper ($0.024 vs $0.146). Claude Opus 5.5 is faster on real-world issues: a median task takes 1m 17s against 3m 31s. Both finished every task on it. The data gives no reason to pick Kimi K3 256K over Claude Opus 5.5 this week.
Changed since W39: Claude Opus 5.5: real-world issues C- to C+, vibe coding B to B+; Kimi K3 256K: real-world issues usage 23% to 21% of the weekly limit, spec planning D+ to C-, spec planning usage 11% to 10% of the weekly limit, vibe coding usage 3% to 2.6% of the weekly limit.
| Dimension | Claude Opus 5.5 | Kimi K3 256K | Advantage |
|---|---|---|---|
| Capability | 73% | 60% | +13% (Claude Opus 5.5 leads) |
| Median task time | 1m 17s | 3m 31s | 2m 15s faster (Claude Opus 5.5 leads) |
| Approx. task cost | $0.015 / task | $0.126 / task | $0.110 / task lower (Claude Opus 5.5 leads) |
Claude Opus 5.5: 11.0% of Claude Max 5x (11.0% / 5h, 1.0% / 1w) per run. Its weekly limit holds about 13.8 of the week's 33.6 5h windows. Kimi K3 256K: 104.0% of Kimi Allegretto (104.0% / 5h, 21.0% / 1w) per run. Its weekly limit holds about 5 of the week's 33.6 5h windows. Each figure is a share of that agent's own plan, so there is no delta to draw.
Work per window: Claude Opus 5.5 1328 vs Kimi K3 256K 140 suite runs per month (Claude Opus 5.5 leads); per plan-dollar: 13.28 vs 3.60 (Claude Opus 5.5 leads). Work figures compare outputs, so unlike quota shares they are comparable across plans.
| Dimension | Claude Opus 5.5 | Kimi K3 256K | Advantage |
|---|---|---|---|
| Capability | 73% | 56% | +17% (Claude Opus 5.5 leads) |
| Median task time | 4m 17s | 5m 26s | 1m 9s faster (Claude Opus 5.5 leads) |
| Approx. task cost | $0.057 / task | $0.224 / task | $0.167 / task lower (Claude Opus 5.5 leads) |
Claude Opus 5.5: 6.0% of Claude Max 5x (6.0% / 5h, 1.0% / 1w) per run. Its weekly limit holds about 13.8 of the week's 33.6 5h windows. Kimi K3 256K: 52.0% of Kimi Allegretto (52.0% / 5h, 10.0% / 1w) per run. Its weekly limit holds about 5 of the week's 33.6 5h windows. Each figure is a share of that agent's own plan, so there is no delta to draw.
Work per window: Claude Opus 5.5 2435 vs Kimi K3 256K 281 suite runs per month (Claude Opus 5.5 leads); per plan-dollar: 24.35 vs 7.20 (Claude Opus 5.5 leads). Work figures compare outputs, so unlike quota shares they are comparable across plans.
| Dimension | Claude Opus 5.5 | Kimi K3 256K | Advantage |
|---|---|---|---|
| Capability | 90% | 34% | +55% (Claude Opus 5.5 leads) |
| Median task time | 2m 44s | 7m 33s | 4m 48s faster (Claude Opus 5.5 leads) |
| Approx. task cost | $0.007 / task | $0.233 / task | $0.226 / task lower (Claude Opus 5.5 leads) |
Claude Opus 5.5: 1.0% of Claude Max 5x (1.0% / 5h) per good solve. Its weekly limit holds about 13.8 of the week's 33.6 5h windows. Kimi K3 256K: 13.2% of Kimi Allegretto (13.2% / 5h, 2.6% / 1w) per good solve. Its weekly limit holds about 5 of the week's 33.6 5h windows. Each figure is a share of that agent's own plan, so there is no delta to draw.
Work per window: Claude Opus 5.5 14610 vs Kimi K3 256K 1107 good solves per month (Claude Opus 5.5 leads); per plan-dollar: 146.10 vs 28.38 (Claude Opus 5.5 leads). Work figures compare outputs, so unlike quota shares they are comparable across plans.
Grades and deltas are comparable only within a suite version. See methodology.
Frequently asked questions
Which is better for coding, Claude Opus 5.5 or Kimi K3 256K?
Both clear tier 4 of 5, but Claude Opus 5.5 scores higher on capability: 73% versus 60% on real-world@v3, our private suite of real-world coding problems. Latest measurement 2026-09-28.
Which is cheaper per task, Claude Opus 5.5 or Kimi K3 256K?
Claude Opus 5.5 used 2% of Claude Max 5x's weekly limit per pass, $0.024 per task at the listed price. Kimi K3 256K used 31% of Kimi Allegretto's weekly limit per pass, $0.146 per task at the listed price. Per task, Claude Opus 5.5 is about 6.0x cheaper ($0.024 vs $0.146).
Which gives more coding work per dollar, Claude Opus 5.5 or Kimi K3 256K?
Claude Opus 5.5 delivers more benchmark work per subscription dollar: 13.28 suite runs per plan-dollar versus 3.60 for Kimi K3 256K (at $100/month priced 2026-07-27, and $39/month priced 2026-07-20). Work figures compare outputs, so unlike raw quota shares they are comparable across plans.
What do Claude Opus 5.5 and Kimi K3 256K cost a month?
Claude Opus 5.5 runs on Claude Max 5x at $100/month (public price as of 2026-07-27). Kimi K3 256K runs on Kimi Allegretto at $39/month (public price as of 2026-07-20).