GPT-5.6 Luna vs Grok 4.5
GPT-5.6 Luna was superseded by GPT-6 Luna. Grok 4.5 was superseded by Grok 4.7. The grades below are the last ones measured, so read them as history rather than as this week's board. See the current roster.
Grok 4.5 leads overall, C- to D. GPT-5.6 Luna is the cheaper side per task (at most $0.012). By suite, Grok 4.5 takes real-world issues (C- to D) and vibe coding (C- to F). Take GPT-5.6 Luna anyway when you want the side that is cheaper per task and 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: Grok 4.5 vs GPT-5.6 Luna
Grok 4.5 leads overall, C- to D. By suite: Grok 4.5 takes real-world issues, C- to D (60% vs 45% capability); Grok 4.5 takes vibe coding, C- to F (59% vs 25% capability). Only GPT-5.6 Luna has run spec planning. GPT-5.6 Luna used <1% of ChatGPT Pro 5x's weekly limit per pass, at most $0.012 per task at the listed price. Grok 4.5 used 6.9% of SuperGrok's weekly limit per pass, $0.032 per task at the listed price. Per task, GPT-5.6 Luna costs at most $0.012 against Grok 4.5's $0.032, so GPT-5.6 Luna is the cheaper side. GPT-5.6 Luna is faster on real-world issues: a median task takes 3m 7s against 3m 9s. Both finished every task on it. Reasons to pick GPT-5.6 Luna anyway: it is cheaper per task (at most $0.012 vs $0.032) and it is faster on real-world issues (3m 7s vs 3m 9s median).
Changed since the previous graded week: GPT-5.6 Luna: spec planning D+ to C-, vibe coding C- to F; Grok 4.5: real-world issues usage 8.0% to 6.9% of the weekly limit.
| Dimension | GPT-5.6 Luna | Grok 4.5 | Advantage |
|---|---|---|---|
| Capability | 45% | 60% | +15% (Grok 4.5 leads) |
| Median task time | 3m 7s | 3m 9s | 2s faster (GPT-5.6 Luna leads) |
| Approx. task cost | <$0.015 / task | $0.032 / task | $0.016 / task lower (GPT-5.6 Luna leads) |
GPT-5.6 Luna: under 1% of ChatGPT Pro 5x per run. Grok 4.5: 6.9% of SuperGrok (6.9% / 1w) per run. Each figure is a share of that agent's own plan, so there is no delta to draw.
Only GPT-5.6 Luna has run this suite, so there is no head-to-head yet.
| Dimension | GPT-5.6 Luna | Grok 4.5 | Advantage |
|---|---|---|---|
| Capability | 25% | 59% | +34% (Grok 4.5 leads) |
| Median task time | 3m 40s | 3m 40s | 0s faster (Grok 4.5 leads) |
| Approx. task cost | <$0.230 / task | $0.031 / task | $0.199 / task lower (Grok 4.5 leads) |
GPT-5.6 Luna: under 1% of ChatGPT Pro 5x per good solve. Grok 4.5: 0.4% of SuperGrok (0.4% / 1w) per good solve. 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-5.6 Luna or Grok 4.5?
Grok 4.5 clears higher: tier 4 of 5 versus tier 1 for GPT-5.6 Luna on real-world@v3, our private suite of real-world coding problems. Latest measurement 2026-09-21.
Which is cheaper per task, GPT-5.6 Luna or Grok 4.5?
GPT-5.6 Luna used <1% of ChatGPT Pro 5x's weekly limit per pass, at most $0.012 per task at the listed price. Grok 4.5 used 6.9% of SuperGrok's weekly limit per pass, $0.032 per task at the listed price. Per task, GPT-5.6 Luna costs at most $0.012 against Grok 4.5's $0.032, so GPT-5.6 Luna is the cheaper side.
What do GPT-5.6 Luna and Grok 4.5 cost a month?
GPT-5.6 Luna runs on ChatGPT Pro 5x at $100/month (public price as of 2026-09-05). Grok 4.5 runs on SuperGrok at $30/month (public price as of 2026-07-20).