GPT-6 Astra vs GPT-6 Luna
GPT-6 Astra leads overall, C- to D. GPT-6 Luna is about 30x cheaper per task. By suite, GPT-6 Luna takes real-world issues (D+ to D) and GPT-6 Astra takes spec planning (C+ to C-). Take GPT-6 Luna anyway when you want the side that is cheaper per task, faster on real-world issues and 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 Luna vs GPT-6 Astra
GPT-6 Astra leads overall, C- to D. By suite: GPT-6 Luna takes real-world issues, D+ to D (50% vs 43% capability); GPT-6 Astra takes spec planning, C+ to C- (73% vs 61% capability); GPT-6 Astra takes vibe coding, C- to F (61% vs 33% capability). GPT-6 Astra used 6% of ChatGPT Pro 5x's weekly limit per pass, $0.073 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 30x cheaper ($0.002 vs $0.073). GPT-6 Luna is faster on real-world issues: a median task takes 1m 0s against 2m 15s. Both finished every task on it. Reasons to pick GPT-6 Luna anyway: it is cheaper per task ($0.002 vs $0.073), it is faster on real-world issues (1m 0s vs 2m 15s median) and it leads on real-world issues (D+ to D).
Changed since W38: GPT-6 Astra: vibe coding C+ to C-.
| Dimension | GPT-6 Astra | GPT-6 Luna | Advantage |
|---|---|---|---|
| Capability | 43% | 50% | +7% (GPT-6 Luna leads) |
| Median task time | 2m 15s | 1m 0s | 1m 15s faster (GPT-6 Luna leads) |
| Approx. task cost | $0.077 / task | $0.003 / task | $0.074 / task lower (GPT-6 Luna leads) |
GPT-6 Astra: 5.0% of ChatGPT Pro 5x (5.0% / 1w) per run. 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 | GPT-6 Astra | GPT-6 Luna | Advantage |
|---|---|---|---|
| Capability | 73% | 61% | +12% (GPT-6 Astra leads) |
| Median task time | 2m 56s | 1m 8s | 1m 48s faster (GPT-6 Luna leads) |
| Approx. task cost | $0.057 / task | <$0.011 / task | $0.046 / task lower (GPT-6 Luna leads) |
GPT-6 Astra: 1.0% of ChatGPT Pro 5x (1.0% / 1w) per run. 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 | GPT-6 Astra | GPT-6 Luna | Advantage |
|---|---|---|---|
| Capability | 61% | 33% | +28% (GPT-6 Astra leads) |
| Median task time | 2m 46s | 1m 37s | 1m 10s faster (GPT-6 Luna leads) |
| Approx. task cost | $0.046 / task | not measured | - |
GPT-6 Astra: 0.2% of ChatGPT Pro 5x (0.2% / 1w) per good solve. 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, GPT-6 Astra or GPT-6 Luna?
Both clear tier 2 of 5, but GPT-6 Luna scores higher on capability: 50% versus 43% on real-world@v3, our private suite of real-world coding problems. Latest measurement 2026-09-20.
Which is cheaper per task, GPT-6 Astra or GPT-6 Luna?
GPT-6 Astra used 6% of ChatGPT Pro 5x's weekly limit per pass, $0.073 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 30x cheaper ($0.002 vs $0.073).
What do GPT-6 Astra and GPT-6 Luna cost a month?
GPT-6 Astra runs on ChatGPT Pro 5x at $100/month (public price as of 2026-09-05). GPT-6 Luna runs on ChatGPT Plus at $20/month (public price as of 2026-07-20).