Claude Fable 5.1 vs Claude Opus 5.5
Claude Opus 5.5 leads overall, C+ to C-. Claude Opus 5.5 is about 11x cheaper per task. By suite, Claude Opus 5.5 takes real-world issues (C- to D+) and spec planning is even at C+. The data gives no reason to pick Claude Fable 5.1 over Claude Opus 5.5 this week.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: Claude Opus 5.5 vs Claude Fable 5.1
Claude Opus 5.5 leads overall, C+ to C-. By suite: Claude Opus 5.5 takes real-world issues, C- to D+ (60% vs 53% capability); spec planning is even at C+ (70% vs 69% capability); Claude Opus 5.5 takes vibe coding, B to C- (85% vs 59% capability). Claude Fable 5.1 used 11% of Claude Max 5x's weekly limit per pass, $0.133 per task at the listed price. Claude Opus 5.5 used 1% of Claude Max 5x's weekly limit per pass, $0.012 per task at the listed price. Per task, Claude Opus 5.5 is about 11x cheaper ($0.012 vs $0.133). Claude Opus 5.5 is faster on real-world issues: a median task takes 2m 18s against 2m 20s. Both finished every task on it. The data gives no reason to pick Claude Fable 5.1 over Claude Opus 5.5 this week.
| Dimension | Claude Fable 5.1 | Claude Opus 5.5 | Advantage |
|---|---|---|---|
| Capability | 53% | 60% | +7% (Claude Opus 5.5 leads) |
| Median task time | 2m 20s | 2m 18s | 2s faster (Claude Opus 5.5 leads) |
| Approx. task cost | $0.107 / task | $0.015 / task | $0.092 / task lower (Claude Opus 5.5 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. Claude Opus 5.5: 16.0% of Claude Max 5x (16.0% / 5h, 1.0% / 1w) per run. Its weekly limit holds about 14.6 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.
Work per window: Claude Fable 5.1 146 vs Claude Opus 5.5 913 suite runs per month (Claude Opus 5.5 leads); per plan-dollar: 1.46 vs 9.13 (Claude Opus 5.5 leads). Work figures compare outputs, so unlike quota shares they are comparable across plans.
| Dimension | Claude Fable 5.1 | Claude Opus 5.5 | Advantage |
|---|---|---|---|
| Capability | 70% | 69% | +1% (Claude Fable 5.1 leads) |
| Median task time | 6m 1s | 3m 45s | 2m 15s faster (Claude Opus 5.5 leads) |
| Approx. task cost | $0.230 / task | $0.010 / task | $0.220 / task lower (Claude Opus 5.5 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. Claude Opus 5.5: 6.0% of Claude Max 5x (6.0% / 5h) per run. Its weekly limit holds about 14.6 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.
Work per window: Claude Fable 5.1 298 vs Claude Opus 5.5 2435 suite runs per month (Claude Opus 5.5 leads); per plan-dollar: 2.98 vs 24.35 (Claude Opus 5.5 leads). Work figures compare outputs, so unlike quota shares they are comparable across plans.
| Dimension | Claude Fable 5.1 | Claude Opus 5.5 | Advantage |
|---|---|---|---|
| Capability | 59% | 85% | +26% (Claude Opus 5.5 leads) |
| Median task time | 3m 58s | 2m 27s | 1m 32s faster (Claude Opus 5.5 leads) |
| Approx. task cost | $0.138 / task | $0.046 / task | $0.092 / task lower (Claude Opus 5.5 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. Claude Opus 5.5: 0.8% of Claude Max 5x (0.8% / 5h, 0.2% / 1w) per good solve. Its weekly limit holds about 14.6 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.
Work per window: Claude Fable 5.1 2356 vs Claude Opus 5.5 18263 good solves per month (Claude Opus 5.5 leads); per plan-dollar: 23.56 vs 182.63 (Claude Opus 5.5 leads). Work figures compare outputs, so unlike quota shares they are comparable across plans.
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 Claude Opus 5.5?
Claude Opus 5.5 clears higher: tier 4 of 5 versus tier 3 for Claude Fable 5.1 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 Claude Opus 5.5?
Claude Fable 5.1 used 11% of Claude Max 5x's weekly limit per pass, $0.133 per task at the listed price. Claude Opus 5.5 used 1% of Claude Max 5x's weekly limit per pass, $0.012 per task at the listed price. Per task, Claude Opus 5.5 is about 11x cheaper ($0.012 vs $0.133).
Which gives more coding work per dollar, Claude Fable 5.1 or Claude Opus 5.5?
Claude Opus 5.5 delivers more benchmark work per subscription dollar: 9.13 suite runs per plan-dollar versus 1.46 for Claude Fable 5.1 (at $100/month priced 2026-07-27, and $100/month priced 2026-07-27). Work figures compare outputs, so unlike raw quota shares they are comparable across plans.
What do Claude Fable 5.1 and Claude Opus 5.5 cost a month?
Claude Fable 5.1 runs on Claude Max 5x at $100/month (public price as of 2026-07-27). Claude Opus 5.5 runs on Claude Max 5x at $100/month (public price as of 2026-07-27).