Gemini 3.8 Flash vs Kimi K3 256K
Gemini 3.8 Flash leads overall, C- to D+. Gemini 3.8 Flash is about 2.5x cheaper per task. By suite, real-world issues is even at C- and Kimi K3 256K takes spec planning (C- to D+). Take Kimi K3 256K anyway when you want the side that is faster on real-world issues and ahead on spec planning.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 Gemini 3.8 Flash
Gemini 3.8 Flash leads overall, C- to D+. By suite: real-world issues is even at C- (60% vs 60% capability); Kimi K3 256K takes spec planning, C- to D+ (56% vs 50% capability); Gemini 3.8 Flash takes vibe coding, C- to F (56% vs 34% capability). Gemini 3.8 Flash used 23.7% of Google AI Pro's weekly limit per pass, $0.057 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, Gemini 3.8 Flash is about 2.5x cheaper ($0.057 vs $0.146). Kimi K3 256K is faster on real-world issues: a median task takes 3m 31s against 5m 21s. Both finished every task on it. Reasons to pick Kimi K3 256K anyway: it is faster on real-world issues (3m 31s vs 5m 21s median) and it leads on spec planning (C- to D+).
Changed since W39: Gemini 3.8 Flash: real-world issues F to C-, real-world issues usage 18.0% to 21.9% of the weekly limit, spec planning usage 2.0% to 1.8% of the weekly limit, vibe coding D+ to C-, vibe coding usage 1.2% to 1.1% of the weekly limit; 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 | Gemini 3.8 Flash | Kimi K3 256K | Advantage |
|---|---|---|---|
| Capability | 60% | 60% | Even |
| Median task time | 5m 21s | 3m 31s | 1m 49s faster (Kimi K3 256K leads) |
| Approx. task cost | $0.067 / task | $0.126 / task | $0.058 / task lower (Gemini 3.8 Flash leads) |
Gemini 3.8 Flash: 21.9% of Google AI Pro (131.3% / 5h, 21.9% / 1w) per run. Its weekly limit holds 6 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.
| Dimension | Gemini 3.8 Flash | Kimi K3 256K | Advantage |
|---|---|---|---|
| Capability | 50% | 56% | +6% (Kimi K3 256K leads) |
| Median task time | 3m 0s | 5m 26s | 2m 26s faster (Gemini 3.8 Flash leads) |
| Approx. task cost | $0.021 / task | $0.224 / task | $0.203 / task lower (Gemini 3.8 Flash leads) |
Gemini 3.8 Flash: 1.8% of Google AI Pro (11.0% / 5h, 1.8% / 1w) per run. Its weekly limit holds 6 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.
| Dimension | Gemini 3.8 Flash | Kimi K3 256K | Advantage |
|---|---|---|---|
| Capability | 56% | 34% | +22% (Gemini 3.8 Flash leads) |
| Median task time | 7m 51s | 7m 33s | 18s faster (Kimi K3 256K leads) |
| Approx. task cost | $0.048 / task | $0.233 / task | $0.185 / task lower (Gemini 3.8 Flash leads) |
Gemini 3.8 Flash: 1.1% of Google AI Pro (6.3% / 5h, 1.1% / 1w) per good solve. Its weekly limit holds 6 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.
Grades and deltas are comparable only within a suite version. See methodology.
Frequently asked questions
Which is better for coding, Gemini 3.8 Flash or Kimi K3 256K?
They are even on our ladder: both clear tier 4 of 5 at 60% capability on real-world@v3, our private suite of real-world coding problems. Latest measurement 2026-09-27.
Which is cheaper per task, Gemini 3.8 Flash or Kimi K3 256K?
Gemini 3.8 Flash used 23.7% of Google AI Pro's weekly limit per pass, $0.057 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, Gemini 3.8 Flash is about 2.5x cheaper ($0.057 vs $0.146).