GPT-6 Astra vs GPT-6 Luna
GPT-6 Astra leads overall, C to D. By suite, GPT-6 Luna takes real-world issues (C- to D) and GPT-6 Astra takes spec planning (C+ to D+). Take GPT-6 Luna anyway when you want the side that is 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, C- to D (57% vs 43% capability); GPT-6 Astra takes spec planning, C+ to D+ (74% vs 55% capability); GPT-6 Astra takes vibe coding, C+ to F (74% vs 31% capability). 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). 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 2m 13s. Both finished every task on it. Reasons to pick GPT-6 Luna anyway: it is faster on real-world issues (1m 4s vs 2m 13s median) and it leads on real-world issues (C- to D).
Changed since W39: GPT-6 Astra has one graded week under this version (W40); GPT-6 Luna: real-world issues D+ to C-, spec planning C- to D+.
| Dimension | GPT-6 Astra | GPT-6 Luna | Advantage |
|---|---|---|---|
| Capability | 43% | 57% | +13% (GPT-6 Luna leads) |
| Median task time | 2m 13s | 1m 4s | 1m 9s faster (GPT-6 Luna leads) |
| Approx. task cost | $0.052 / task | not measured | - |
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. 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 | GPT-6 Astra | GPT-6 Luna | Advantage |
|---|---|---|---|
| Capability | 74% | 55% | +19% (GPT-6 Astra leads) |
| Median task time | 3m 5s | 1m 20s | 1m 45s 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: 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. 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 | 74% | 31% | +43% (GPT-6 Astra leads) |
| Median task time | 2m 40s | 1m 24s | 1m 16s faster (GPT-6 Luna leads) |
| Approx. task cost | $0.046 / task | <$0.046 / task | Even |
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. 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, GPT-6 Astra or GPT-6 Luna?
Both clear tier 2 of 5, but GPT-6 Luna scores higher on capability: 57% versus 43% on real-world@v3, our private suite of real-world coding problems. Latest measurement 2026-09-28.
Which is cheaper per task, GPT-6 Astra or GPT-6 Luna?
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). 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).
What do GPT-6 Astra and GPT-6 Luna cost a month?
GPT-6 Astra runs on ChatGPT Plus at $20/month (public price as of 2026-07-20). GPT-6 Luna runs on ChatGPT Plus at $20/month (public price as of 2026-07-20).