GPT-5.6 Sol vs GPT-6 Luna
GPT-5.6 Sol was superseded by GPT-6.1 Sol. The grades below are the last ones measured, so read them as history rather than as this week's board. See the current roster.
GPT-5.6 Sol leads overall, C- to D. By suite, real-world issues is even at C- and GPT-5.6 Sol takes spec planning (C+ to D+). Take GPT-6 Luna anyway when you want the side that is faster on real-world issues. Both agents run the same private suite cut headless through their own tools, each on its own subscription.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-5.6 Sol
GPT-5.6 Sol leads overall, C- to D. By suite: real-world issues is even at C- (60% vs 57% capability); GPT-5.6 Sol takes spec planning, C+ to D+ (68% vs 55% capability); GPT-5.6 Sol takes vibe coding, D+ to F (51% vs 31% capability). GPT-5.6 Sol used 3% of ChatGPT Pro 5x's weekly limit per pass, $0.036 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 3m 13s. Both finished every task on it. Reasons to pick GPT-6 Luna anyway: it is faster on real-world issues (1m 4s vs 3m 13s median).
Changed since the previous graded week: GPT-5.6 Sol: vibe coding C- to D+; GPT-6 Luna: real-world issues D+ to C-, spec planning C- to D+.
| Dimension | GPT-5.6 Sol | GPT-6 Luna | Advantage |
|---|---|---|---|
| Capability | 60% | 57% | +3% (GPT-5.6 Sol leads) |
| Median task time | 3m 13s | 1m 4s | 2m 9s faster (GPT-6 Luna leads) |
| Approx. task cost | $0.031 / task | not measured | - |
GPT-5.6 Sol: 2.0% of ChatGPT Pro 5x (2.0% / 1w) per run. 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-5.6 Sol | GPT-6 Luna | Advantage |
|---|---|---|---|
| Capability | 68% | 55% | +13% (GPT-5.6 Sol leads) |
| Median task time | 6m 0s | 1m 20s | 4m 39s faster (GPT-6 Luna leads) |
| Approx. task cost | $0.057 / task | <$0.011 / task | $0.046 / task lower (GPT-6 Luna leads) |
GPT-5.6 Sol: 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-5.6 Sol | GPT-6 Luna | Advantage |
|---|---|---|---|
| Capability | 51% | 31% | +20% (GPT-5.6 Sol leads) |
| Median task time | 3m 56s | 1m 24s | 2m 32s faster (GPT-6 Luna leads) |
| Approx. task cost | $0.092 / task | <$0.046 / task | $0.046 / task lower (GPT-6 Luna leads) |
GPT-5.6 Sol: 0.4% of ChatGPT Pro 5x (0.4% / 1w) per good solve. 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-5.6 Sol or GPT-6 Luna?
GPT-5.6 Sol clears higher: tier 4 of 5 versus tier 2 for GPT-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 Sol or GPT-6 Luna?
GPT-5.6 Sol used 3% of ChatGPT Pro 5x's weekly limit per pass, $0.036 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 GPT-5.6 Sol and GPT-6 Luna cost a month?
GPT-5.6 Sol 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).