GPT-5.6 Terra vs Grok 4.6
Grok 4.6 was superseded by Grok 4.7. The grades below are the last ones measured, so read them as history rather than as this week's board. See the current roster.
Grok 4.6 leads overall, C- to D. GPT-5.6 Terra is about 8.1x cheaper per task. By suite, GPT-5.6 Terra takes real-world issues (D+ to D) and Grok 4.6 takes spec planning (C to D+). Take GPT-5.6 Terra anyway when you want the side that is cheaper per task, faster on real-world issues and ahead 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: Grok 4.6 vs GPT-5.6 Terra
Grok 4.6 leads overall, C- to D. By suite: GPT-5.6 Terra takes real-world issues, D+ to D (50% vs 47% capability); Grok 4.6 takes spec planning, C to D+ (66% vs 53% capability); Grok 4.6 takes vibe coding, C- to F (61% vs 34% 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). Grok 4.6 used 13% of SuperGrok Plus's weekly limit per pass, $0.157 per task at the listed price. Per task, GPT-5.6 Terra is about 8.1x cheaper ($0.019 vs $0.157). GPT-5.6 Terra is faster on real-world issues: a median task takes 2m 18s against 7m 10s. Both finished every task on it. Reasons to pick GPT-5.6 Terra anyway: it is cheaper per task ($0.019 vs $0.157), it is faster on real-world issues (2m 18s vs 7m 10s median) and it leads on real-world issues (D+ to D).
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; Grok 4.6: real-world issues C- to D, real-world issues usage 4% to 3% of the weekly limit, vibe coding C+ to C-.
| Dimension | GPT-5.6 Terra | Grok 4.6 | Advantage |
|---|---|---|---|
| Capability | 50% | 47% | +3% (GPT-5.6 Terra leads) |
| Median task time | 2m 18s | 7m 10s | 4m 53s faster (GPT-5.6 Terra leads) |
| Approx. task cost | $0.021 / task | $0.046 / task | $0.025 / task lower (GPT-5.6 Terra 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. Grok 4.6: 3.0% of SuperGrok Plus (3.0% / 1w) 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 | Grok 4.6 | Advantage |
|---|---|---|---|
| Capability | 53% | 66% | +12% (Grok 4.6 leads) |
| Median task time | 2m 37s | 45m 26s | 42m 48s faster (GPT-5.6 Terra leads) |
| Approx. task cost | $0.011 / task | $0.575 / task | $0.563 / 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. Grok 4.6: 10.0% of SuperGrok Plus (10.0% / 1w) 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 | Grok 4.6 | Advantage |
|---|---|---|---|
| Capability | 34% | 61% | +27% (Grok 4.6 leads) |
| Median task time | 2m 47s | 11m 14s | 8m 26s faster (GPT-5.6 Terra leads) |
| Approx. task cost | $0.028 / task | <$0.230 / task | $0.202 / task lower (GPT-5.6 Terra 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. Grok 4.6: under 1% of SuperGrok Plus 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 Grok 4.6?
Grok 4.6 clears higher: tier 4 of 5 versus tier 2 for GPT-5.6 Terra 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 Grok 4.6?
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). Grok 4.6 used 13% of SuperGrok Plus's weekly limit per pass, $0.157 per task at the listed price. Per task, GPT-5.6 Terra is about 8.1x cheaper ($0.019 vs $0.157).
What do GPT-5.6 Terra and Grok 4.6 cost a month?
GPT-5.6 Terra runs on ChatGPT Plus at $20/month (public price as of 2026-07-20). Grok 4.6 runs on SuperGrok Plus at $100/month (public price as of 2026-09-14).