Claude Opus 5 vs GPT-6 Luna
Claude Opus 5 was superseded by Claude Opus 5.5. The grades below are the last ones measured, so read them as history rather than as this week's board. See the current roster.
Claude Opus 5 leads overall, C to D. By suite, real-world issues is even at C- and Claude Opus 5 takes spec planning (C to D+). Take GPT-6 Luna anyway when you want the side that is faster 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 Claude Opus 5
Claude Opus 5 leads overall, C to D. By suite: real-world issues is even at C- (57% vs 57% capability); Claude Opus 5 takes spec planning, C to D+ (66% vs 55% capability); Claude Opus 5 takes vibe coding, C+ to F (72% vs 31% capability). Claude Opus 5 used 2% of Claude Max 5x's weekly limit per pass, $0.024 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 1m 56s. Both finished every task on it. Reasons to pick GPT-6 Luna anyway: it is faster on real-world issues (1m 4s vs 1m 56s median).
Changed since the previous graded week: Claude Opus 5: real-world issues usage 3% to 1% of the weekly limit; GPT-6 Luna: real-world issues D+ to C-, spec planning C- to D+.
| Dimension | Claude Opus 5 | GPT-6 Luna | Advantage |
|---|---|---|---|
| Capability | 57% | 57% | Even |
| Median task time | 1m 56s | 1m 4s | 51s faster (GPT-6 Luna leads) |
| Approx. task cost | $0.015 / task | not measured | - |
Claude Opus 5: 21.0% of Claude Max 5x (21.0% / 5h, 1.0% / 1w) per run. Its weekly limit holds about 13.8 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 | Claude Opus 5 | GPT-6 Luna | Advantage |
|---|---|---|---|
| Capability | 66% | 55% | +11% (Claude Opus 5 leads) |
| Median task time | 2m 9s | 1m 20s | 48s faster (GPT-6 Luna leads) |
| Approx. task cost | $0.057 / task | <$0.011 / task | $0.046 / task lower (GPT-6 Luna leads) |
Claude Opus 5: 6.0% of Claude Max 5x (6.0% / 5h, 1.0% / 1w) per run. Its weekly limit holds about 13.8 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 | Claude Opus 5 | GPT-6 Luna | Advantage |
|---|---|---|---|
| Capability | 72% | 31% | +41% (Claude Opus 5 leads) |
| Median task time | 2m 51s | 1m 24s | 1m 28s faster (GPT-6 Luna leads) |
| Approx. task cost | $0.011 / task | <$0.046 / task | $0.035 / task lower (Claude Opus 5 leads) |
Claude Opus 5: 1.6% of Claude Max 5x (1.6% / 5h) per good solve. Its weekly limit holds about 13.8 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, Claude Opus 5 or GPT-6 Luna?
They are even on our ladder: both clear tier 2 of 5 at 57% capability on real-world@v3, our private suite of real-world coding problems. Latest measurement 2026-09-21.
Which is cheaper per task, Claude Opus 5 or GPT-6 Luna?
Claude Opus 5 used 2% of Claude Max 5x's weekly limit per pass, $0.024 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).
What do Claude Opus 5 and GPT-6 Luna cost a month?
Claude Opus 5 runs on Claude Max 5x at $100/month (public price as of 2026-07-27). GPT-6 Luna runs on ChatGPT Plus at $20/month (public price as of 2026-07-20).