Claude Fable 5.1 vs GPT-6 Sol
Claude Fable 5.1 leads overall, C- to D+. GPT-6 Sol is about 11x cheaper per task. By suite, Claude Fable 5.1 takes real-world issues (D+ to D-) and spec planning (C+ to C). Take GPT-6 Sol anyway when you want the side that is cheaper per task.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 Claude Fable 5.1
Claude Fable 5.1 leads overall, C- to D+. By suite: Claude Fable 5.1 takes real-world issues, D+ to D- (53% vs 38% capability); Claude Fable 5.1 takes spec planning, C+ to C (70% vs 64% capability); Claude Fable 5.1 takes vibe coding, C- to D+ (59% vs 51% capability). Claude Fable 5.1 used 11% of Claude Max 5x's weekly limit per pass, $0.133 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 11x cheaper ($0.012 vs $0.133). Claude Fable 5.1 is faster on real-world issues: a median task takes 2m 20s against 2m 44s. Both finished every task on it. Reasons to pick GPT-6 Sol anyway: it is cheaper per task ($0.012 vs $0.133).
| Dimension | Claude Fable 5.1 | GPT-6 Sol | Advantage |
|---|---|---|---|
| Capability | 53% | 38% | +15% (Claude Fable 5.1 leads) |
| Median task time | 2m 20s | 2m 44s | 24s faster (Claude Fable 5.1 leads) |
| Approx. task cost | $0.107 / task | $0.012 / task | $0.095 / task lower (GPT-6 Sol leads) |
Claude Fable 5.1: 100.0% of Claude Max 5x (100.0% / 5h, 7.0% / 1w) per run. Its weekly limit holds about 14.6 of the week's 33.6 5h windows. 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 | Claude Fable 5.1 | GPT-6 Sol | Advantage |
|---|---|---|---|
| Capability | 70% | 64% | +6% (Claude Fable 5.1 leads) |
| Median task time | 6m 1s | 2m 23s | 3m 38s faster (GPT-6 Sol leads) |
| Approx. task cost | $0.230 / task | $0.011 / task | $0.218 / task lower (GPT-6 Sol leads) |
Claude Fable 5.1: 49.0% of Claude Max 5x (49.0% / 5h, 4.0% / 1w) per run. Its weekly limit holds about 14.6 of the week's 33.6 5h windows. 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 | Claude Fable 5.1 | GPT-6 Sol | Advantage |
|---|---|---|---|
| Capability | 59% | 51% | +8% (Claude Fable 5.1 leads) |
| Median task time | 3m 58s | 3m 4s | 54s faster (GPT-6 Sol leads) |
| Approx. task cost | $0.138 / task | $0.018 / task | $0.120 / task lower (GPT-6 Sol leads) |
Claude Fable 5.1: 6.2% of Claude Max 5x (6.2% / 5h, 0.6% / 1w) per good solve. Its weekly limit holds about 14.6 of the week's 33.6 5h windows. 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, Claude Fable 5.1 or GPT-6 Sol?
Claude Fable 5.1 clears higher: tier 3 of 5 versus tier 1 for GPT-6 Sol on real-world@v3, our private suite of real-world coding problems. Latest measurement 2026-09-20.
Which is cheaper per task, Claude Fable 5.1 or GPT-6 Sol?
Claude Fable 5.1 used 11% of Claude Max 5x's weekly limit per pass, $0.133 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 11x cheaper ($0.012 vs $0.133).
What do Claude Fable 5.1 and GPT-6 Sol cost a month?
Claude Fable 5.1 runs on Claude Max 5x at $100/month (public price as of 2026-07-27). GPT-6 Sol runs on ChatGPT Plus at $20/month (public price as of 2026-07-20).