Claude Opus 5.5 vs GPT-6 Astra
Claude Opus 5.5 leads overall, C+ to C-. Claude Opus 5.5 is about 6.0x cheaper per task. By suite, Claude Opus 5.5 takes real-world issues (C- to D) and spec planning is even at C+. Take GPT-6 Astra anyway when you want the side that is 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: GPT-6 Astra vs Claude Opus 5.5
Claude Opus 5.5 leads overall, C+ to C-. By suite: Claude Opus 5.5 takes real-world issues, C- to D (60% vs 43% capability); spec planning is even at C+ (69% vs 73% capability); Claude Opus 5.5 takes vibe coding, B to C- (85% vs 61% capability). Claude Opus 5.5 used 1% of Claude Max 5x's weekly limit per pass, $0.012 per task at the listed price. GPT-6 Astra used 6% of ChatGPT Pro 5x's weekly limit per pass, $0.073 per task at the listed price. Per task, Claude Opus 5.5 is about 6.0x cheaper ($0.012 vs $0.073). GPT-6 Astra is faster on real-world issues: a median task takes 2m 15s against 2m 18s. Both finished every task on it. Reasons to pick GPT-6 Astra anyway: it is faster on real-world issues (2m 15s vs 2m 18s median).
Changed since W38: GPT-6 Astra: vibe coding C+ to C-.
| Dimension | Claude Opus 5.5 | GPT-6 Astra | Advantage |
|---|---|---|---|
| Capability | 60% | 43% | +17% (Claude Opus 5.5 leads) |
| Median task time | 2m 18s | 2m 15s | 3s faster (GPT-6 Astra leads) |
| Approx. task cost | $0.015 / task | $0.077 / task | $0.061 / task lower (Claude Opus 5.5 leads) |
Claude Opus 5.5: 16.0% of Claude Max 5x (16.0% / 5h, 1.0% / 1w) per run. Its weekly limit holds about 14.6 of the week's 33.6 5h windows. GPT-6 Astra: 5.0% of ChatGPT Pro 5x (5.0% / 1w) per run. Each figure is a share of that agent's own plan, so there is no delta to draw.
| Dimension | Claude Opus 5.5 | GPT-6 Astra | Advantage |
|---|---|---|---|
| Capability | 69% | 73% | +4% (GPT-6 Astra leads) |
| Median task time | 3m 45s | 2m 56s | 49s faster (GPT-6 Astra leads) |
| Approx. task cost | $0.010 / task | $0.057 / task | $0.047 / task lower (Claude Opus 5.5 leads) |
Claude Opus 5.5: 6.0% of Claude Max 5x (6.0% / 5h) per run. Its weekly limit holds about 14.6 of the week's 33.6 5h windows. GPT-6 Astra: 1.0% of ChatGPT Pro 5x (1.0% / 1w) per run. Each figure is a share of that agent's own plan, so there is no delta to draw.
| Dimension | Claude Opus 5.5 | GPT-6 Astra | Advantage |
|---|---|---|---|
| Capability | 85% | 61% | +23% (Claude Opus 5.5 leads) |
| Median task time | 2m 27s | 2m 46s | 20s faster (Claude Opus 5.5 leads) |
| Approx. task cost | $0.046 / task | $0.046 / task | Even |
Claude Opus 5.5: 0.8% of Claude Max 5x (0.8% / 5h, 0.2% / 1w) per good solve. Its weekly limit holds about 14.6 of the week's 33.6 5h windows. GPT-6 Astra: 0.2% of ChatGPT Pro 5x (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 Opus 5.5 or GPT-6 Astra?
Claude Opus 5.5 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 2026-09-23.
Which is cheaper per task, Claude Opus 5.5 or GPT-6 Astra?
Claude Opus 5.5 used 1% of Claude Max 5x's weekly limit per pass, $0.012 per task at the listed price. GPT-6 Astra used 6% of ChatGPT Pro 5x's weekly limit per pass, $0.073 per task at the listed price. Per task, Claude Opus 5.5 is about 6.0x cheaper ($0.012 vs $0.073).
What do Claude Opus 5.5 and GPT-6 Astra cost a month?
Claude Opus 5.5 runs on Claude Max 5x at $100/month (public price as of 2026-07-27). GPT-6 Astra runs on ChatGPT Pro 5x at $100/month (public price as of 2026-09-05).