GPT-5.6 Sol vs GPT-6 Sol
GPT-5.6 Sol leads overall, C- to D+. GPT-6 Sol is about 3.0x cheaper per task. By suite, GPT-5.6 Sol takes real-world issues (C- to D-) and spec planning (C+ to C). Take GPT-6 Sol 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: GPT-6 Sol vs GPT-5.6 Sol
GPT-5.6 Sol leads overall, C- to D+. By suite: GPT-5.6 Sol takes real-world issues, C- to D- (60% vs 38% capability); GPT-5.6 Sol takes spec planning, C+ to C (68% vs 64% capability); vibe coding is even at D+ (51% vs 51% 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 Sol used 5% of ChatGPT Plus's weekly limit per pass, $0.012 per task at the listed price; at the ~$100 tier the board defaults to that is an estimated ~1% of ChatGPT Pro 5x's weekly limit (est, about $0.012 per task). Per task, GPT-6 Sol is about 3.0x cheaper ($0.012 vs $0.036). GPT-6 Sol is faster on real-world issues: a median task takes 2m 44s against 3m 13s. Both finished every task on it. Reasons to pick GPT-6 Sol anyway: it is cheaper per task ($0.012 vs $0.036) and it is faster on real-world issues (2m 44s vs 3m 13s median).
Changed since W38: GPT-5.6 Sol: vibe coding C- to D+.
| Dimension | GPT-5.6 Sol | GPT-6 Sol | Advantage |
|---|---|---|---|
| Capability | 60% | 38% | +22% (GPT-5.6 Sol leads) |
| Median task time | 3m 13s | 2m 44s | 29s faster (GPT-6 Sol leads) |
| Approx. task cost | $0.031 / task | $0.012 / task | $0.018 / task lower (GPT-6 Sol leads) |
GPT-5.6 Sol: 2.0% of ChatGPT Pro 5x (2.0% / 1w) per run. GPT-6 Sol: 4.0% of ChatGPT Plus (37.0% / 5h, 4.0% / 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-5.6 Sol | GPT-6 Sol | Advantage |
|---|---|---|---|
| Capability | 68% | 64% | +5% (GPT-5.6 Sol leads) |
| Median task time | 6m 0s | 2m 23s | 3m 37s faster (GPT-6 Sol leads) |
| Approx. task cost | $0.057 / task | $0.011 / task | $0.046 / task lower (GPT-6 Sol leads) |
GPT-5.6 Sol: 1.0% of ChatGPT Pro 5x (1.0% / 1w) per run. GPT-6 Sol: 1.0% of ChatGPT Plus (8.0% / 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-5.6 Sol | GPT-6 Sol | Advantage |
|---|---|---|---|
| Capability | 51% | 51% | Even |
| Median task time | 3m 56s | 3m 4s | 52s faster (GPT-6 Sol leads) |
| Approx. task cost | $0.092 / task | $0.018 / task | $0.074 / task lower (GPT-6 Sol leads) |
GPT-5.6 Sol: 0.4% of ChatGPT Pro 5x (0.4% / 1w) per good solve. GPT-6 Sol: 0.4% of ChatGPT Plus (2.4% / 5h, 0.4% / 1w) 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 Sol?
GPT-5.6 Sol clears higher: tier 4 of 5 versus tier 1 for GPT-6 Sol 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 Sol?
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 Sol used 5% of ChatGPT Plus's weekly limit per pass, $0.012 per task at the listed price; at the ~$100 tier the board defaults to that is an estimated ~1% of ChatGPT Pro 5x's weekly limit (est, about $0.012 per task). Per task, GPT-6 Sol is about 3.0x cheaper ($0.012 vs $0.036).
What do GPT-5.6 Sol and GPT-6 Sol cost a month?
GPT-5.6 Sol runs on ChatGPT Pro 5x at $100/month (public price as of 2026-09-05). GPT-6 Sol runs on ChatGPT Plus at $20/month (public price as of 2026-07-20).