Gemini 3.1 Pro vs GPT-6 Luna
GPT-6 Luna leads overall, D to F. By suite, GPT-6 Luna takes real-world issues (C- to D+) and spec planning (D+ to F). The data gives no reason to pick Gemini 3.1 Pro over GPT-6 Luna this week. Both agents run the same private suite cut headless through their own tools, each on its own subscription.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: GPT-6 Luna vs Gemini 3.1 Pro
GPT-6 Luna leads overall, D to F. By suite: GPT-6 Luna takes real-world issues, C- to D+ (57% vs 53% capability); GPT-6 Luna takes spec planning, D+ to F (55% vs 21% capability); vibe coding is even at F (27% vs 31% capability). Gemini 3.1 Pro used 15.9% of Google AI Pro's weekly limit per pass, $0.038 per task at the listed price. GPT-6 Luna used <1% of ChatGPT Plus's weekly limit per pass; at the ~$100 tier the board defaults to that is an estimated ~<0.2% of ChatGPT Pro 5x's weekly limit (est). GPT-6 Luna is faster on real-world issues: a median task takes 1m 4s against 4m 53s. Both finished every task on it. The data gives no reason to pick Gemini 3.1 Pro over GPT-6 Luna this week.
Changed since W39: Gemini 3.1 Pro: real-world issues usage 9.8% to 14.8% of the weekly limit, spec planning usage 0.9% to 1.1% of the weekly limit, vibe coding usage 1.0% to 0.7% of the weekly limit; GPT-6 Luna: real-world issues D+ to C-, spec planning C- to D+.
| Dimension | Gemini 3.1 Pro | GPT-6 Luna | Advantage |
|---|---|---|---|
| Capability | 53% | 57% | +3% (GPT-6 Luna leads) |
| Median task time | 4m 53s | 1m 4s | 3m 49s faster (GPT-6 Luna leads) |
| Approx. task cost | $0.045 / task | not measured | - |
Gemini 3.1 Pro: 14.8% of Google AI Pro (88.9% / 5h, 14.8% / 1w) per run. Its weekly limit holds 6 of the week's 33.6 5h windows. GPT-6 Luna: under 1% of ChatGPT Plus (2.0% / 5h) per run. Its weekly limit holds about 6 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 3.1 Pro | GPT-6 Luna | Advantage |
|---|---|---|---|
| Capability | 21% | 55% | +34% (GPT-6 Luna leads) |
| Median task time | 1m 46s | 1m 20s | 26s faster (GPT-6 Luna leads) |
| Approx. task cost | $0.013 / task | <$0.011 / task | $0.001 / task lower (GPT-6 Luna leads) |
Gemini 3.1 Pro: 1.1% of Google AI Pro (6.5% / 5h, 1.1% / 1w) per run. Its weekly limit holds 6 of the week's 33.6 5h windows. GPT-6 Luna: under 1% of ChatGPT Plus per run. Its weekly limit holds about 6 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 3.1 Pro | GPT-6 Luna | Advantage |
|---|---|---|---|
| Capability | 27% | 31% | +4% (GPT-6 Luna leads) |
| Median task time | 4m 38s | 1m 24s | 3m 14s faster (GPT-6 Luna leads) |
| Approx. task cost | $0.034 / task | <$0.046 / task | $0.012 / task lower (Gemini 3.1 Pro leads) |
Gemini 3.1 Pro: 0.7% of Google AI Pro (4.4% / 5h, 0.7% / 1w) per good solve. Its weekly limit holds 6 of the week's 33.6 5h windows. GPT-6 Luna: under 1% of ChatGPT Plus per good solve. Its weekly limit holds about 6 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 3.1 Pro or GPT-6 Luna?
Gemini 3.1 Pro clears higher: tier 3 of 5 versus tier 2 for GPT-6 Luna on real-world@v3, our private suite of real-world coding problems. Latest measurement 2026-09-28.
Which is cheaper per task, Gemini 3.1 Pro or GPT-6 Luna?
Gemini 3.1 Pro used 15.9% of Google AI Pro's weekly limit per pass, $0.038 per task at the listed price. GPT-6 Luna used <1% of ChatGPT Plus's weekly limit per pass; at the ~$100 tier the board defaults to that is an estimated ~<0.2% of ChatGPT Pro 5x's weekly limit (est).