Gemini 3.1 Pro vs GPT-6 Luna
GPT-6 Luna leads overall, D to F. GPT-6 Luna is about 11x cheaper per task. By suite, real-world issues is even at D+ and GPT-6 Luna takes spec planning (C- to F). The data gives no reason to pick Gemini 3.1 Pro over GPT-6 Luna 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: GPT-6 Luna vs Gemini 3.1 Pro
GPT-6 Luna leads overall, D to F. By suite: real-world issues is even at D+ (53% vs 50% capability); GPT-6 Luna takes spec planning, C- to F (61% vs 15% capability); vibe coding is even at F (35% vs 33% capability). Gemini 3.1 Pro used 10.8% of Google AI Pro's weekly limit per pass, $0.026 per task at the listed price. GPT-6 Luna used 1% of ChatGPT Plus's weekly limit per pass, $0.002 per task at the listed price; at the ~$100 tier the board defaults to that is an estimated ~0.2% of ChatGPT Pro 5x's weekly limit (est, about $0.002 per task). Per task, GPT-6 Luna is about 11x cheaper ($0.002 vs $0.026). GPT-6 Luna is faster on real-world issues: a median task takes 1m 0s against 2m 55s. 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 W38: Gemini 3.1 Pro: real-world issues F to D+, real-world issues usage 11.2% to 9.8% of the weekly limit, spec planning usage 1.0% to 0.9% of the weekly limit.
| Dimension | Gemini 3.1 Pro | GPT-6 Luna | Advantage |
|---|---|---|---|
| Capability | 53% | 50% | +3% (Gemini 3.1 Pro leads) |
| Median task time | 2m 55s | 1m 0s | 1m 55s faster (GPT-6 Luna leads) |
| Approx. task cost | $0.030 / task | $0.003 / task | $0.027 / task lower (GPT-6 Luna leads) |
Gemini 3.1 Pro: 9.8% of Google AI Pro (59.0% / 5h, 9.8% / 1w) per run. Its weekly limit holds 6 of the week's 33.6 5h windows. GPT-6 Luna: 1.0% of ChatGPT Plus (1.0% / 5h, 1.0% / 1w) 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 | 15% | 61% | +45% (GPT-6 Luna leads) |
| Median task time | 1m 46s | 1m 8s | 38s faster (GPT-6 Luna leads) |
| Approx. task cost | $0.011 / task | <$0.011 / task | $0.001 / task lower (Gemini 3.1 Pro leads) |
Gemini 3.1 Pro: 0.9% of Google AI Pro (5.6% / 5h, 0.9% / 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 | 35% | 33% | +2% (Gemini 3.1 Pro leads) |
| Median task time | 4m 33s | 1m 37s | 2m 56s faster (GPT-6 Luna leads) |
| Approx. task cost | $0.045 / task | not measured | - |
Gemini 3.1 Pro: 1.0% of Google AI Pro (5.8% / 5h, 1.0% / 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 (0.4% / 5h) 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 2026-09-21.
Which is cheaper per task, Gemini 3.1 Pro or GPT-6 Luna?
Gemini 3.1 Pro used 10.8% of Google AI Pro's weekly limit per pass, $0.026 per task at the listed price. GPT-6 Luna used 1% of ChatGPT Plus's weekly limit per pass, $0.002 per task at the listed price; at the ~$100 tier the board defaults to that is an estimated ~0.2% of ChatGPT Pro 5x's weekly limit (est, about $0.002 per task). Per task, GPT-6 Luna is about 11x cheaper ($0.002 vs $0.026).