Claude Fable 5 vs GPT-6 Astra
Claude Fable 5 was superseded by Claude Fable 5.1. The grades below are the last ones measured, so read them as history rather than as this week's board. See the current roster.
Both grade C overall. GPT-6 Astra is about 3.2x cheaper per task. By suite, Claude Fable 5 takes real-world issues (C- to D) and GPT-6 Astra takes spec planning (C+ to C). Both agents run the same private suite cut headless through their own tools, each on its own subscription.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-6 Astra vs Claude Fable 5
Both grade C overall. By suite: Claude Fable 5 takes real-world issues, C- to D (60% vs 43% capability); GPT-6 Astra takes spec planning, C+ to C (74% vs 63% capability); vibe coding is even at C+ (74% vs 74% 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-6 Astra used 22% of ChatGPT Plus's weekly limit per pass, $0.053 per task at the listed price; at the ~$100 tier the board defaults to that is an estimated ~4.4% of ChatGPT Pro 5x's weekly limit (est, about $0.053 per task). Per task, GPT-6 Astra is about 3.2x cheaper ($0.053 vs $0.169). GPT-6 Astra is faster on real-world issues: a median task takes 2m 13s against 2m 37s. Both finished every task on it.
Changed since W35: Claude Fable 5: real-world issues C+ to C-, vibe coding C to C+; GPT-6 Astra has one graded week under this version (W40).
| Dimension | Claude Fable 5 | GPT-6 Astra | Advantage |
|---|---|---|---|
| Capability | 60% | 43% | +17% (Claude Fable 5 leads) |
| Median task time | 2m 37s | 2m 13s | 23s faster (GPT-6 Astra leads) |
| Approx. task cost | $0.153 / task | $0.052 / task | $0.101 / task lower (GPT-6 Astra 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-6 Astra: 17.0% of ChatGPT Plus (112.0% / 5h, 17.0% / 1w) per run. Its weekly limit holds about 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.
| Dimension | Claude Fable 5 | GPT-6 Astra | Advantage |
|---|---|---|---|
| Capability | 63% | 74% | +11% (GPT-6 Astra leads) |
| Median task time | 5m 32s | 3m 5s | 2m 27s faster (GPT-6 Astra leads) |
| Approx. task cost | $0.230 / task | $0.057 / task | $0.172 / task lower (GPT-6 Astra 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-6 Astra: 5.0% of ChatGPT Plus (27.0% / 5h, 5.0% / 1w) per run. Its weekly limit holds about 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.
| Dimension | Claude Fable 5 | GPT-6 Astra | Advantage |
|---|---|---|---|
| Capability | 74% | 74% | Even |
| Median task time | 5m 28s | 2m 40s | 2m 49s faster (GPT-6 Astra leads) |
| Approx. task cost | $0.184 / task | $0.046 / task | $0.138 / task lower (GPT-6 Astra 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-6 Astra: 1.0% of ChatGPT Plus (7.2% / 5h, 1.0% / 1w) per good solve. Its weekly limit holds about 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.
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-6 Astra?
Claude Fable 5 clears higher: tier 4 of 5 versus tier 2 for GPT-6 Astra 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-6 Astra?
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-6 Astra used 22% of ChatGPT Plus's weekly limit per pass, $0.053 per task at the listed price; at the ~$100 tier the board defaults to that is an estimated ~4.4% of ChatGPT Pro 5x's weekly limit (est, about $0.053 per task). Per task, GPT-6 Astra is about 3.2x cheaper ($0.053 vs $0.169).
What do Claude Fable 5 and GPT-6 Astra cost a month?
Claude Fable 5 runs on Claude Max 20x at $200/month (public price as of 2026-08-05). GPT-6 Astra runs on ChatGPT Plus at $20/month (public price as of 2026-07-20).