GPT-6.1 Sol vs Kimi K3 256K
GPT-6.1 Sol leads overall, C to D+. GPT-6.1 Sol is about 10x cheaper per task. By suite, real-world issues is even at C- and GPT-6.1 Sol takes spec planning (C+ to C-). The data gives no reason to pick Kimi K3 256K over GPT-6.1 Sol 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 GPT-6.1 Sol
GPT-6.1 Sol leads overall, C to D+. By suite: real-world issues is even at C- (57% vs 60% capability); GPT-6.1 Sol takes spec planning, C+ to C- (73% vs 56% capability); GPT-6.1 Sol takes vibe coding, C+ to F (72% vs 34% capability). GPT-6.1 Sol used 6% of ChatGPT Plus's weekly limit per pass, $0.015 per task at the listed price; at the ~$100 tier the board defaults to that is an estimated ~1.2% of ChatGPT Pro 5x's weekly limit (est, about $0.015 per task). Kimi K3 256K used 31% of Kimi Allegretto's weekly limit per pass, $0.146 per task at the listed price. Per task, GPT-6.1 Sol is about 10x cheaper ($0.015 vs $0.146). GPT-6.1 Sol is faster on real-world issues: a median task takes 3m 26s against 3m 31s. Both finished every task on it. The data gives no reason to pick Kimi K3 256K over GPT-6.1 Sol this week.
Changed since W39: GPT-6.1 Sol has one graded week under this version (W40); 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 | GPT-6.1 Sol | Kimi K3 256K | Advantage |
|---|---|---|---|
| Capability | 57% | 60% | +3% (Kimi K3 256K leads) |
| Median task time | 3m 26s | 3m 31s | 5s faster (GPT-6.1 Sol leads) |
| Approx. task cost | $0.012 / task | $0.126 / task | $0.113 / task lower (GPT-6.1 Sol leads) |
GPT-6.1 Sol: 4.0% of ChatGPT Plus (28.0% / 5h, 4.0% / 1w) per run. Its weekly limit holds about 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 | GPT-6.1 Sol | Kimi K3 256K | Advantage |
|---|---|---|---|
| Capability | 73% | 56% | +17% (GPT-6.1 Sol leads) |
| Median task time | 6m 22s | 5m 26s | 56s faster (Kimi K3 256K leads) |
| Approx. task cost | $0.023 / task | $0.224 / task | $0.201 / task lower (GPT-6.1 Sol leads) |
GPT-6.1 Sol: 2.0% of ChatGPT Plus (9.0% / 5h, 2.0% / 1w) per run. Its weekly limit holds about 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 | GPT-6.1 Sol | Kimi K3 256K | Advantage |
|---|---|---|---|
| Capability | 72% | 34% | +37% (GPT-6.1 Sol leads) |
| Median task time | 4m 55s | 7m 33s | 2m 38s faster (GPT-6.1 Sol leads) |
| Approx. task cost | $0.018 / task | $0.233 / task | $0.215 / task lower (GPT-6.1 Sol leads) |
GPT-6.1 Sol: 0.4% of ChatGPT Plus (2.2% / 5h, 0.4% / 1w) per good solve. Its weekly limit holds about 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, GPT-6.1 Sol or Kimi K3 256K?
Kimi K3 256K clears higher: tier 4 of 5 versus tier 2 for GPT-6.1 Sol on real-world@v3, our private suite of real-world coding problems. Latest measurement 2026-09-30.
Which is cheaper per task, GPT-6.1 Sol or Kimi K3 256K?
GPT-6.1 Sol used 6% of ChatGPT Plus's weekly limit per pass, $0.015 per task at the listed price; at the ~$100 tier the board defaults to that is an estimated ~1.2% of ChatGPT Pro 5x's weekly limit (est, about $0.015 per task). Kimi K3 256K used 31% of Kimi Allegretto's weekly limit per pass, $0.146 per task at the listed price. Per task, GPT-6.1 Sol is about 10x cheaper ($0.015 vs $0.146).
What do GPT-6.1 Sol and Kimi K3 256K cost a month?
GPT-6.1 Sol runs on ChatGPT Plus at $20/month (public price as of 2026-07-20). Kimi K3 256K runs on Kimi Allegretto at $39/month (public price as of 2026-07-20).