GPT-5.6 Terra vs Composer 2.5
Both grade D overall. The two cost about the same per task. By suite, Composer 2.5 takes real-world issues (C- to D+) and GPT-5.6 Terra takes spec planning (D+ to D). 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: Composer 2.5 vs GPT-5.6 Terra
Both grade D overall. By suite: Composer 2.5 takes real-world issues, C- to D+ (57% vs 50% capability); GPT-5.6 Terra takes spec planning, D+ to D (53% vs 48% capability); vibe coding is even at F (34% vs 23% capability). GPT-5.6 Terra used 8% of ChatGPT Plus's weekly limit per pass, $0.019 per task at the listed price; at the ~$100 tier the board defaults to that is an estimated ~1.6% of ChatGPT Pro 5x's weekly limit (est, about $0.019 per task). Composer 2.5 used 2.0% of Cursor Pro's monthly limit per pass, $0.021 per task at the listed price. Per task the two cost about the same ($0.019 vs $0.021). Composer 2.5 is faster on real-world issues: a median task takes 1m 34s against 2m 18s. Both finished every task on it.
Changed since the previous graded week: GPT-5.6 Terra: real-world issues D to D+, real-world issues usage 9.2% to 7% of the weekly limit, spec planning C- to D+, spec planning usage 2.0% to 1% of the weekly limit, vibe coding F to D, vibe coding usage 0.5% to 0.6% of the weekly limit; Composer 2.5: real-world issues D+ to C-.
| Dimension | GPT-5.6 Terra | Composer 2.5 | Advantage |
|---|---|---|---|
| Capability | 50% | 57% | +7% (Composer 2.5 leads) |
| Median task time | 2m 18s | 1m 34s | 43s faster (Composer 2.5 leads) |
| Approx. task cost | $0.021 / task | $0.021 / task | $0.000 / task lower (Composer 2.5 leads) |
GPT-5.6 Terra: 7.0% of ChatGPT Plus (46.0% / 5h, 7.0% / 1w) per run. Its weekly limit holds about 6 of the week's 33.6 5h windows. Composer 2.5: 1.6% of Cursor Pro (1.6% / 1m) per run. Each figure is a share of that agent's own plan, so there is no delta to draw.
| Dimension | GPT-5.6 Terra | Composer 2.5 | Advantage |
|---|---|---|---|
| Capability | 53% | 48% | +5% (GPT-5.6 Terra leads) |
| Median task time | 2m 37s | 1m 8s | 1m 30s faster (Composer 2.5 leads) |
| Approx. task cost | $0.011 / task | $0.022 / task | $0.011 / task lower (GPT-5.6 Terra leads) |
GPT-5.6 Terra: 1.0% of ChatGPT Plus (10.0% / 5h, 1.0% / 1w) per run. Its weekly limit holds about 6 of the week's 33.6 5h windows. Composer 2.5: 0.4% of Cursor Pro (0.4% / 1m) per run. Each figure is a share of that agent's own plan, so there is no delta to draw.
| Dimension | GPT-5.6 Terra | Composer 2.5 | Advantage |
|---|---|---|---|
| Capability | 34% | 23% | +12% (GPT-5.6 Terra leads) |
| Median task time | 2m 47s | 1m 37s | 1m 11s faster (Composer 2.5 leads) |
| Approx. task cost | $0.028 / task | $0.022 / task | $0.006 / task lower (Composer 2.5 leads) |
GPT-5.6 Terra: 0.6% of ChatGPT Plus (3.0% / 5h, 0.6% / 1w) per good solve. Its weekly limit holds about 6 of the week's 33.6 5h windows. Composer 2.5: 0.1% of Cursor Pro (0.1% / 1m) 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, GPT-5.6 Terra or Composer 2.5?
GPT-5.6 Terra clears higher: tier 2 of 5 versus tier 1 for Composer 2.5 on real-world@v3, our private suite of real-world coding problems. Latest measurement 2026-09-28.
Which is cheaper per task, GPT-5.6 Terra or Composer 2.5?
GPT-5.6 Terra used 8% of ChatGPT Plus's weekly limit per pass, $0.019 per task at the listed price; at the ~$100 tier the board defaults to that is an estimated ~1.6% of ChatGPT Pro 5x's weekly limit (est, about $0.019 per task). Composer 2.5 used 2.0% of Cursor Pro's monthly limit per pass, $0.021 per task at the listed price. Per task the two cost about the same ($0.019 vs $0.021).
What do GPT-5.6 Terra and Composer 2.5 cost a month?
GPT-5.6 Terra runs on ChatGPT Plus at $20/month (public price as of 2026-07-20). Composer 2.5 runs on Cursor Pro at $20/month (public price as of 2026-07-20).