Claude Fable 5.1 vs Claude Sonnet 5
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.
| Dimension | Claude Fable 5.1 | Claude Sonnet 5 | Advantage |
|---|---|---|---|
| Capability | 73% | 47% | +27% (Claude Fable 5.1 leads) |
| Median task time | 1m 46s | 3m 2s | 1m 16s faster (Claude Fable 5.1 leads) |
| Approx. task cost | $0.026 / task | $0.005 / task | $0.021 / task lower (Claude Sonnet 5 leads) |
Claude Fable 5.1: 28.0% of Claude Max 20x (28.0% / 5h, 5.0% / 1w) per run. Its weekly limit holds about 7.2 of the week's 33.6 5h windows. Claude Sonnet 5: 5.0% of Claude Max 20x (5.0% / 5h, 1.0% / 1w) per run. Its weekly limit holds about 7.2 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 5.1 522 vs Claude Sonnet 5 2922 suite runs per month (Claude Sonnet 5 leads); per plan-dollar: 2.61 vs 14.61 (Claude Sonnet 5 leads). Work figures compare outputs, so unlike quota shares they are comparable across plans.
| Dimension | Claude Fable 5.1 | Claude Sonnet 5 | Advantage |
|---|---|---|---|
| Capability | 74% | 53% | +22% (Claude Fable 5.1 leads) |
| Median task time | 6m 51s | 3m 31s | 3m 20s faster (Claude Sonnet 5 leads) |
| Approx. task cost | $0.051 / task | $0.003 / task | $0.048 / task lower (Claude Sonnet 5 leads) |
Claude Fable 5.1: 15.0% of Claude Max 20x (15.0% / 5h, 2.0% / 1w) per run. Its weekly limit holds about 7.2 of the week's 33.6 5h windows. Claude Sonnet 5: 1.0% of Claude Max 20x (1.0% / 5h) per run. Its weekly limit holds about 7.2 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 5.1 974 vs Claude Sonnet 5 14610 suite runs per month (Claude Sonnet 5 leads); per plan-dollar: 4.87 vs 73.05 (Claude Sonnet 5 leads). Work figures compare outputs, so unlike quota shares they are comparable across plans.
| Dimension | Claude Fable 5.1 | Claude Sonnet 5 | Advantage |
|---|---|---|---|
| Capability | 85% | 34% | +50% (Claude Fable 5.1 leads) |
| Median task time | 3m 48s | 4m 50s | 1m 2s faster (Claude Fable 5.1 leads) |
| Approx. task cost | $0.025 / task | $0.003 / task | $0.022 / task lower (Claude Sonnet 5 leads) |
Claude Fable 5.1: 1.8% of Claude Max 20x (1.8% / 5h, 0.2% / 1w) per good solve. Its weekly limit holds about 7.2 of the week's 33.6 5h windows. Claude Sonnet 5: 0.2% of Claude Max 20x (0.2% / 5h) per good solve. Its weekly limit holds about 7.2 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 8117 vs Claude Sonnet 5 73050 good solves per month (Claude Sonnet 5 leads); per plan-dollar: 40.58 vs 365.25 (Claude Sonnet 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 Sonnet 5?
Both clear tier 4 of 5, but Claude Fable 5.1 scores higher on capability: 73% versus 47% on real-world@v3, our private suite of real-world coding problems. Latest measurement 2026-09-01.
Which gives more work per dollar, Claude Fable 5.1 or Claude Sonnet 5?
Claude Sonnet 5 delivers more benchmark work per subscription dollar: 14.61 suite runs per plan-dollar versus 2.61 for Claude Fable 5.1 (at $200/month priced 2026-08-05, and $200/month priced 2026-08-05). Work figures compare outputs, so unlike raw quota shares they are comparable across plans.
How much do Claude Fable 5.1 and Claude Sonnet 5 cost?
Claude Fable 5.1 runs on Claude Max 20x at $200/month (public price as of 2026-08-05). Claude Sonnet 5 runs on Claude Max 20x at $200/month (public price as of 2026-08-05).