Claude Fable 5.1 vs Grok 4.5
Grok 4.5 was superseded by Grok 4.7. 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 5.1 leads overall, B- to C-. Grok 4.5 is about 3.1x cheaper per task. By suite, Claude Fable 5.1 takes real-world issues (B+ to C-) and vibe coding (C+ to C-). Take Grok 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: Grok 4.5 vs Claude Fable 5.1
Claude Fable 5.1 leads overall, B- to C-. By suite: Claude Fable 5.1 takes real-world issues, B+ to C- (87% vs 60% capability); Claude Fable 5.1 takes vibe coding, C+ to C- (74% vs 59% capability). Only Claude Fable 5.1 has run spec planning. Claude Fable 5.1 used 8% of Claude Max 5x's weekly limit per pass, $0.097 per task at the listed price. Grok 4.5 used 6.9% of SuperGrok's weekly limit per pass, $0.032 per task at the listed price. Per task, Grok 4.5 is about 3.1x cheaper ($0.032 vs $0.097). Grok 4.5 is faster on real-world issues: a median task takes 3m 9s against 3m 38s. Both finished every task on it. Reasons to pick Grok 4.5 anyway: it is cheaper per task ($0.032 vs $0.097) and it is faster on real-world issues (3m 9s vs 3m 38s median).
Changed since the previous graded week: 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; Grok 4.5: real-world issues usage 8.0% to 6.9% of the weekly limit.
| Dimension | Claude Fable 5.1 | Grok 4.5 | Advantage |
|---|---|---|---|
| Capability | 87% | 60% | +27% (Claude Fable 5.1 leads) |
| Median task time | 3m 38s | 3m 9s | 28s faster (Grok 4.5 leads) |
| Approx. task cost | $0.077 / task | $0.032 / task | $0.045 / task lower (Grok 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. Grok 4.5: 6.9% of SuperGrok (6.9% / 1w) per run. Each figure is a share of that agent's own plan, so there is no delta to draw.
Only Claude Fable 5.1 has run this suite, so there is no head-to-head yet.
| Dimension | Claude Fable 5.1 | Grok 4.5 | Advantage |
|---|---|---|---|
| Capability | 74% | 59% | +15% (Claude Fable 5.1 leads) |
| Median task time | 4m 14s | 3m 40s | 34s faster (Grok 4.5 leads) |
| Approx. task cost | $0.092 / task | $0.031 / task | $0.061 / task lower (Grok 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. Grok 4.5: 0.4% of SuperGrok (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 5.1 or Grok 4.5?
Both clear tier 4 of 5, but Claude Fable 5.1 scores higher on capability: 87% versus 60% 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 Grok 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. Grok 4.5 used 6.9% of SuperGrok's weekly limit per pass, $0.032 per task at the listed price. Per task, Grok 4.5 is about 3.1x cheaper ($0.032 vs $0.097).
What do Claude Fable 5.1 and Grok 4.5 cost a month?
Claude Fable 5.1 runs on Claude Max 5x at $100/month (public price as of 2026-07-27). Grok 4.5 runs on SuperGrok at $30/month (public price as of 2026-07-20).