Claude Fable 5.1 vs Claude Haiku 4.5
Claude Fable 5.1 leads overall, B- to F. Claude Haiku 4.5 is about 8.0x cheaper per task. By suite, Claude Fable 5.1 takes real-world issues (B+ to D-) and spec planning (C+ to F). Take Claude Haiku 4.5 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: Claude Haiku 4.5 vs Claude Fable 5.1
Claude Fable 5.1 leads overall, B- to F. By suite: Claude Fable 5.1 takes real-world issues, B+ to D- (87% vs 37% capability); Claude Fable 5.1 takes spec planning, C+ to F (71% vs 21% capability); Claude Fable 5.1 takes vibe coding, C+ to F (74% vs 22% capability). Claude Fable 5.1 used 8% of Claude Max 5x's weekly limit per pass, $0.097 per task at the listed price. Claude Haiku 4.5 used 1% of Claude Max 5x's weekly limit per pass, $0.012 per task at the listed price. Per task, Claude Haiku 4.5 is about 8.0x cheaper ($0.012 vs $0.097). Claude Haiku 4.5 is faster on real-world issues: a median task takes 3m 8s against 3m 38s. Both finished every task on it. Reasons to pick Claude Haiku 4.5 anyway: it is cheaper per task ($0.012 vs $0.097) and it is faster on real-world issues (3m 8s vs 3m 38s median).
Changed since W39: Claude Fable 5.1: real-world issues D+ to B+, real-world issues usage 7% to 5% of the weekly limit, spec planning usage 4% to 3% of the weekly limit, vibe coding C- to C+, vibe coding usage 0.6% to 0.4% of the weekly limit; Claude Haiku 4.5: real-world issues D+ to D-.
| Dimension | Claude Fable 5.1 | Claude Haiku 4.5 | Advantage |
|---|---|---|---|
| Capability | 87% | 37% | +50% (Claude Fable 5.1 leads) |
| Median task time | 3m 38s | 3m 8s | 30s faster (Claude Haiku 4.5 leads) |
| Approx. task cost | $0.077 / task | $0.015 / task | $0.061 / task lower (Claude Haiku 4.5 leads) |
Claude Fable 5.1: 64.0% of Claude Max 5x (64.0% / 5h, 5.0% / 1w) per run. Its weekly limit holds about 13.8 of the week's 33.6 5h windows. Claude Haiku 4.5: 8.0% of Claude Max 5x (8.0% / 5h, 1.0% / 1w) per run. Its weekly limit holds about 13.8 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 5.1 228 vs Claude Haiku 4.5 1826 suite runs per month (Claude Haiku 4.5 leads); per plan-dollar: 2.28 vs 18.26 (Claude Haiku 4.5 leads). Work figures compare outputs, so unlike quota shares they are comparable across plans.
| Dimension | Claude Fable 5.1 | Claude Haiku 4.5 | Advantage |
|---|---|---|---|
| Capability | 71% | 21% | +50% (Claude Fable 5.1 leads) |
| Median task time | 8m 55s | 2m 8s | 6m 47s faster (Claude Haiku 4.5 leads) |
| Approx. task cost | $0.172 / task | $0.002 / task | $0.171 / task lower (Claude Haiku 4.5 leads) |
Claude Fable 5.1: 33.0% of Claude Max 5x (33.0% / 5h, 3.0% / 1w) per run. Its weekly limit holds about 13.8 of the week's 33.6 5h windows. Claude Haiku 4.5: 1.0% of Claude Max 5x (1.0% / 5h) per run. Its weekly limit holds about 13.8 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 5.1 443 vs Claude Haiku 4.5 14610 suite runs per month (Claude Haiku 4.5 leads); per plan-dollar: 4.43 vs 146.10 (Claude Haiku 4.5 leads). Work figures compare outputs, so unlike quota shares they are comparable across plans.
| Dimension | Claude Fable 5.1 | Claude Haiku 4.5 | Advantage |
|---|---|---|---|
| Capability | 74% | 22% | +52% (Claude Fable 5.1 leads) |
| Median task time | 4m 14s | 4m 4s | 10s faster (Claude Haiku 4.5 leads) |
| Approx. task cost | $0.092 / task | $0.009 / task | $0.083 / task lower (Claude Haiku 4.5 leads) |
Claude Fable 5.1: 4.2% of Claude Max 5x (4.2% / 5h, 0.4% / 1w) per good solve. Its weekly limit holds about 13.8 of the week's 33.6 5h windows. Claude Haiku 4.5: 1.3% of Claude Max 5x (1.3% / 5h) per good solve. Its weekly limit holds about 13.8 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 3479 vs Claude Haiku 4.5 11688 good solves per month (Claude Haiku 4.5 leads); per plan-dollar: 34.79 vs 116.88 (Claude Haiku 4.5 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 Haiku 4.5?
Claude Fable 5.1 clears higher: tier 4 of 5 versus tier 2 for Claude Haiku 4.5 on real-world@v3, our private suite of real-world coding problems. Latest measurement 2026-09-27.
Which is cheaper per task, Claude Fable 5.1 or Claude Haiku 4.5?
Claude Fable 5.1 used 8% of Claude Max 5x's weekly limit per pass, $0.097 per task at the listed price. Claude Haiku 4.5 used 1% of Claude Max 5x's weekly limit per pass, $0.012 per task at the listed price. Per task, Claude Haiku 4.5 is about 8.0x cheaper ($0.012 vs $0.097).
Which gives more coding work per dollar, Claude Fable 5.1 or Claude Haiku 4.5?
Claude Haiku 4.5 delivers more benchmark work per subscription dollar: 18.26 suite runs per plan-dollar versus 2.28 for Claude Fable 5.1 (at $100/month priced 2026-07-20, 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 Haiku 4.5 cost a month?
Claude Fable 5.1 runs on Claude Max 5x at $100/month (public price as of 2026-07-27). Claude Haiku 4.5 runs on Claude Max 5x at $100/month (public price as of 2026-07-20).