Claude Opus 5.5 vs GPT-6 Astra
Claude Opus 5.5 leads overall, B- to C. Claude Opus 5.5 is about 2.2x cheaper per task. By suite, Claude Opus 5.5 takes real-world issues (C+ to D) and spec planning is even at C+. The data gives no reason to pick GPT-6 Astra over Claude Opus 5.5 this week.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, B- to C. By suite: Claude Opus 5.5 takes real-world issues, C+ to D (73% vs 43% capability); spec planning is even at C+ (73% vs 74% capability); Claude Opus 5.5 takes vibe coding, B+ to C+ (90% vs 74% capability). Claude Opus 5.5 used 2% of Claude Max 5x's weekly limit per pass, $0.024 per task at the listed price. 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, Claude Opus 5.5 is about 2.2x cheaper ($0.024 vs $0.053). Claude Opus 5.5 is faster on real-world issues: a median task takes 1m 17s against 2m 13s. Both finished every task on it. The data gives no reason to pick GPT-6 Astra over Claude Opus 5.5 this week.
Changed since W39: Claude Opus 5.5: real-world issues C- to C+, vibe coding B to B+; GPT-6 Astra has one graded week under this version (W40).
| Dimension | Claude Opus 5.5 | GPT-6 Astra | Advantage |
|---|---|---|---|
| Capability | 73% | 43% | +30% (Claude Opus 5.5 leads) |
| Median task time | 1m 17s | 2m 13s | 57s faster (Claude Opus 5.5 leads) |
| Approx. task cost | $0.015 / task | $0.052 / task | $0.037 / task lower (Claude Opus 5.5 leads) |
Claude Opus 5.5: 11.0% of Claude Max 5x (11.0% / 5h, 1.0% / 1w) per run. Its weekly limit holds about 13.8 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 Opus 5.5 | GPT-6 Astra | Advantage |
|---|---|---|---|
| Capability | 73% | 74% | +2% (GPT-6 Astra leads) |
| Median task time | 4m 17s | 3m 5s | 1m 12s faster (GPT-6 Astra leads) |
| Approx. task cost | $0.057 / task | $0.057 / task | Even |
Claude Opus 5.5: 6.0% of Claude Max 5x (6.0% / 5h, 1.0% / 1w) per run. Its weekly limit holds about 13.8 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 Opus 5.5 | GPT-6 Astra | Advantage |
|---|---|---|---|
| Capability | 90% | 74% | +15% (Claude Opus 5.5 leads) |
| Median task time | 2m 44s | 2m 40s | 4s faster (GPT-6 Astra leads) |
| Approx. task cost | $0.007 / task | $0.046 / task | $0.039 / task lower (Claude Opus 5.5 leads) |
Claude Opus 5.5: 1.0% of Claude Max 5x (1.0% / 5h) per good solve. Its weekly limit holds about 13.8 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 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 2026-09-28.
Which is cheaper per task, Claude Opus 5.5 or GPT-6 Astra?
Claude Opus 5.5 used 2% of Claude Max 5x's weekly limit per pass, $0.024 per task at the listed price. 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, Claude Opus 5.5 is about 2.2x cheaper ($0.024 vs $0.053).
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 Plus at $20/month (public price as of 2026-07-20).