Claude Fable 5 vs GPT-5.6 Sol
Claude Fable 5 was superseded by Claude Fable 5.1. GPT-5.6 Sol was superseded by GPT-6.1 Sol.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.
Claude Fable 5 leads overall, C to C-. GPT-5.6 Sol is about 4.7x cheaper per task. By suite, real-world issues is even at C- and GPT-5.6 Sol takes spec planning (C+ to C). Take GPT-5.6 Sol anyway when you want the side that is cheaper per task and ahead on spec planning.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-5.6 Sol vs Claude Fable 5
Claude Fable 5 leads overall, C to C-. By suite: real-world issues is even at C- (60% vs 60% capability); GPT-5.6 Sol takes spec planning, C+ to C (68% vs 63% capability); Claude Fable 5 takes vibe coding, C+ to D+ (74% vs 51% capability). Claude Fable 5 used 7% of Claude Max 20x's weekly limit per pass, $0.169 per task at the listed price; at the ~$100 tier the board defaults to that is an estimated ~14% of Claude Max 5x's weekly limit (est, about $0.169 per task). GPT-5.6 Sol used 3% of ChatGPT Pro 5x's weekly limit per pass, $0.036 per task at the listed price. Per task, GPT-5.6 Sol is about 4.7x cheaper ($0.036 vs $0.169). Claude Fable 5 is faster on real-world issues: a median task takes 2m 37s against 3m 13s. Both finished every task on it. Reasons to pick GPT-5.6 Sol anyway: it is cheaper per task ($0.036 vs $0.169) and it leads on spec planning (C+ to C).
Changed since the previous graded week: Claude Fable 5: real-world issues C+ to C-, vibe coding C to C+; GPT-5.6 Sol: vibe coding C- to D+.
| Dimension | Claude Fable 5 | GPT-5.6 Sol | Advantage |
|---|---|---|---|
| Capability | 60% | 60% | Even |
| Median task time | 2m 37s | 3m 13s | 36s faster (Claude Fable 5 leads) |
| Approx. task cost | $0.153 / task | $0.031 / task | $0.123 / task lower (GPT-5.6 Sol leads) |
Claude Fable 5: 33.0% of Claude Max 20x (33.0% / 5h, 5.0% / 1w) per run. Its weekly limit holds about 7 of the week's 33.6 5h windows. GPT-5.6 Sol: 2.0% of ChatGPT Pro 5x (2.0% / 1w) per run. Each figure is a share of that agent's own plan, so there is no delta to draw.
| Dimension | Claude Fable 5 | GPT-5.6 Sol | Advantage |
|---|---|---|---|
| Capability | 63% | 68% | +5% (GPT-5.6 Sol leads) |
| Median task time | 5m 32s | 6m 0s | 28s faster (Claude Fable 5 leads) |
| Approx. task cost | $0.230 / task | $0.057 / task | $0.172 / task lower (GPT-5.6 Sol leads) |
Claude Fable 5: 10.0% of Claude Max 20x (10.0% / 5h, 2.0% / 1w) per run. Its weekly limit holds about 7 of the week's 33.6 5h windows. GPT-5.6 Sol: 1.0% of ChatGPT Pro 5x (1.0% / 1w) per run. Each figure is a share of that agent's own plan, so there is no delta to draw.
| Dimension | Claude Fable 5 | GPT-5.6 Sol | Advantage |
|---|---|---|---|
| Capability | 74% | 51% | +23% (Claude Fable 5 leads) |
| Median task time | 5m 28s | 3m 56s | 1m 32s faster (GPT-5.6 Sol leads) |
| Approx. task cost | $0.184 / task | $0.092 / task | $0.092 / task lower (GPT-5.6 Sol leads) |
Claude Fable 5: 2.8% of Claude Max 20x (2.8% / 5h, 0.4% / 1w) per good solve. Its weekly limit holds about 7 of the week's 33.6 5h windows. GPT-5.6 Sol: 0.4% of ChatGPT Pro 5x (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, Claude Fable 5 or GPT-5.6 Sol?
They are even on our ladder: both clear tier 4 of 5 at 60% capability on real-world@v3, our private suite of real-world coding problems. Latest measurement 2026-08-30.
Which is cheaper per task, Claude Fable 5 or GPT-5.6 Sol?
Claude Fable 5 used 7% of Claude Max 20x's weekly limit per pass, $0.169 per task at the listed price; at the ~$100 tier the board defaults to that is an estimated ~14% of Claude Max 5x's weekly limit (est, about $0.169 per task). GPT-5.6 Sol used 3% of ChatGPT Pro 5x's weekly limit per pass, $0.036 per task at the listed price. Per task, GPT-5.6 Sol is about 4.7x cheaper ($0.036 vs $0.169).
What do Claude Fable 5 and GPT-5.6 Sol cost a month?
Claude Fable 5 runs on Claude Max 20x at $200/month (public price as of 2026-08-05). GPT-5.6 Sol runs on ChatGPT Pro 5x at $100/month (public price as of 2026-09-05).