claude-fable-5 vs gpt-5.6-terra
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 | gpt-5.6-terra | Advantage |
|---|---|---|---|
| Capability | 60% | 53% | +7% (claude-fable-5 leads) |
| Median task time | 3m 12s | 1m 49s | 1m 24s faster (gpt-5.6-terra leads) |
| Approx. task cost | $0.031 / task | $0.007 / task | $0.024 / task lower (gpt-5.6-terra leads) |
claude-fable-5: 34.0% of Claude Max 20x (34.0% / 5h, 5.0% / 1w) per run. gpt-5.6-terra: 2.4% of ChatGPT Plus (2.4% / 1w) per run. Each figure is a share of that agent's own plan, so there is no delta to draw.
| Dimension | claude-fable-5 | gpt-5.6-terra | Advantage |
|---|---|---|---|
| Capability | 64% | 62% | +2% (claude-fable-5 leads) |
| Median task time | 5m 54s | 2m 15s | 3m 39s faster (gpt-5.6-terra leads) |
| Approx. task cost | $0.041 / task | $0.005 / task | $0.036 / task lower (gpt-5.6-terra leads) |
claude-fable-5: 12.0% of Claude Max 20x (12.0% / 5h, 1.0% / 1w) per run. gpt-5.6-terra: 0.4% of ChatGPT Plus (0.4% / 1w) per run. Each figure is a share of that agent's own plan, so there is no delta to draw.
| Dimension | claude-fable-5 | gpt-5.6-terra | Advantage |
|---|---|---|---|
| Capability | 69% | 38% | +31% (claude-fable-5 leads) |
| Median task time | 5m 25s | 2m 52s | 2m 33s faster (gpt-5.6-terra leads) |
| Approx. task cost | $0.038 / task | $0.008 / task | $0.031 / task lower (gpt-5.6-terra leads) |
claude-fable-5: 2.8% of Claude Max 20x (2.8% / 5h, 0.6% / 1w) per good solve. gpt-5.6-terra: 0.2% of ChatGPT Plus (0.2% / 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 or gpt-5.6-terra?
claude-fable-5 clears higher: tier 4 of 5 versus tier 3 for gpt-5.6-terra on real-world@v3, our private suite of real-world coding problems. Latest measurement 2026-08-17.
How much do claude-fable-5 and gpt-5.6-terra cost?
claude-fable-5 runs on Claude Max 20x at $200/month (public price as of 2026-08-05). gpt-5.6-terra runs on ChatGPT Plus at $20/month (public price as of 2026-07-20).