gpt-5.6-luna 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 | gpt-5.6-luna | gpt-5.6-terra | Advantage |
|---|---|---|---|
| Capability | 53% | 53% | Even |
| Median task time | 1m 59s | 1m 49s | 10s faster (gpt-5.6-terra leads) |
| Approx. task cost | $0.009 / task | $0.007 / task | $0.001 / task lower (gpt-5.6-terra leads) |
gpt-5.6-luna: 2.9% of ChatGPT Plus (2.9% / 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 | gpt-5.6-luna | gpt-5.6-terra | Advantage |
|---|---|---|---|
| Capability | 58% | 62% | +5% (gpt-5.6-terra leads) |
| Median task time | 2m 11s | 2m 15s | 4s faster (gpt-5.6-luna leads) |
| Approx. task cost | $0.004 / task | $0.005 / task | $0.001 / task lower (gpt-5.6-luna leads) |
gpt-5.6-luna: 0.3% of ChatGPT Plus (0.3% / 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 | gpt-5.6-luna | gpt-5.6-terra | Advantage |
|---|---|---|---|
| Capability | 28% | 38% | +10% (gpt-5.6-terra leads) |
| Median task time | 2m 44s | 2m 52s | 9s faster (gpt-5.6-luna leads) |
| Approx. task cost | $0.008 / task | $0.008 / task | $0.000 / task lower (gpt-5.6-luna leads) |
gpt-5.6-luna: 0.2% of ChatGPT Plus (0.2% / 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, gpt-5.6-luna or gpt-5.6-terra?
They are even on our ladder: both clear tier 3 of 5 at 53% capability on real-world@v3, our private suite of real-world coding problems. Latest measurement 2026-08-17.
How much do gpt-5.6-luna and gpt-5.6-terra cost?
gpt-5.6-luna runs on ChatGPT Plus at $20/month (public price as of 2026-07-20). gpt-5.6-terra runs on ChatGPT Plus at $20/month (public price as of 2026-07-20).