Gemini 3.8 Flash vs GPT-6 Astra
GPT-6 Astra leads overall, C to C-. The two cost about the same per task. By suite, Gemini 3.8 Flash takes real-world issues (C- to D) and GPT-6 Astra takes spec planning (C+ to D+). Take Gemini 3.8 Flash anyway when you want the side that is ahead on real-world issues.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 Astra vs Gemini 3.8 Flash
GPT-6 Astra leads overall, C to C-. By suite: Gemini 3.8 Flash takes real-world issues, C- to D (60% vs 43% capability); GPT-6 Astra takes spec planning, C+ to D+ (74% vs 50% capability); GPT-6 Astra takes vibe coding, C+ to C- (74% vs 56% 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. GPT-6 Astra used 22% of ChatGPT Plus's weekly limit per pass, $0.053 per task at the listed price; at the ~$100 tier the board defaults to that is an estimated ~4.4% of ChatGPT Pro 5x's weekly limit (est, about $0.053 per task). Per task the two cost about the same ($0.057 vs $0.053). GPT-6 Astra is faster on real-world issues: a median task takes 2m 13s against 5m 21s. Both finished every task on it. Reasons to pick Gemini 3.8 Flash anyway: it leads on real-world issues (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; GPT-6 Astra has one graded week under this version (W40).
| Dimension | Gemini 3.8 Flash | GPT-6 Astra | Advantage |
|---|---|---|---|
| Capability | 60% | 43% | +17% (Gemini 3.8 Flash leads) |
| Median task time | 5m 21s | 2m 13s | 3m 7s faster (GPT-6 Astra leads) |
| Approx. task cost | $0.067 / task | $0.052 / task | $0.015 / task lower (GPT-6 Astra 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. GPT-6 Astra: 17.0% of ChatGPT Plus (112.0% / 5h, 17.0% / 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 3.8 Flash | GPT-6 Astra | Advantage |
|---|---|---|---|
| Capability | 50% | 74% | +24% (GPT-6 Astra leads) |
| Median task time | 3m 0s | 3m 5s | 5s faster (Gemini 3.8 Flash leads) |
| Approx. task cost | $0.021 / task | $0.057 / task | $0.036 / 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. GPT-6 Astra: 5.0% of ChatGPT Plus (27.0% / 5h, 5.0% / 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 3.8 Flash | GPT-6 Astra | Advantage |
|---|---|---|---|
| Capability | 56% | 74% | +18% (GPT-6 Astra leads) |
| Median task time | 7m 51s | 2m 40s | 5m 11s faster (GPT-6 Astra leads) |
| Approx. task cost | $0.048 / task | $0.046 / task | $0.002 / task lower (GPT-6 Astra 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. GPT-6 Astra: 1.0% of ChatGPT Plus (7.2% / 5h, 1.0% / 1w) 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 3.8 Flash or GPT-6 Astra?
Gemini 3.8 Flash clears higher: tier 4 of 5 versus tier 2 for GPT-6 Astra 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 GPT-6 Astra?
Gemini 3.8 Flash used 23.7% of Google AI Pro's weekly limit per pass, $0.057 per task at the listed price. GPT-6 Astra used 22% of ChatGPT Plus's weekly limit per pass, $0.053 per task at the listed price; at the ~$100 tier the board defaults to that is an estimated ~4.4% of ChatGPT Pro 5x's weekly limit (est, about $0.053 per task). Per task the two cost about the same ($0.057 vs $0.053).