specs at a glance
| Leaderboard rank | #4 of 29 |
|---|---|
| SWE-bench Verified | 95.4% |
| SWE-bench Pro | — |
| Terminal-Bench | — |
| Input price / 1M | $2 |
| Output price / 1M | $12 |
| Context window | 1M |
| Open weights | No |
| Access | API · OpenAI platform |
| Maker | OpenAI |
how good is GPT-5.6 Terra at coding?
GPT-5.6 Terra sits at #4 of 29 ranked models, posting 95.4% on SWE-bench Verified — 1.6 points behind #1 Claude Opus 5.
Score provenance: Independent (vals.ai, re-evaluated, mini-swe-agent bash-only harness): SWE-bench Verified 95.4% ±0.94, 5th of 86 systems. CORRECTION, 2026-08-20: this row previously carried 75.2% ±1.93 (32nd of 75), the figure vals.ai published on Jul 22 2026 and which we added Jul 27, 2026. A routine sweep found vals.ai had re-run the model and revised the score up by 20.2 points; the old figure and the reading we built on it, that Terra was the weakest of the three GPT-5.6 tiers, are both withdrawn.
A jump that large on an unchanged model points at the first run rather than the model, so read 95.4% as the corrected measurement and not as an improvement. Terra now sits second among the GPT-5.6 tiers, behind Sol at 96.2% and ahead of Luna at 93.0%. Treat it as tied with GLM-5.3 (also 95.4% ±0.94), Grok 4.6 (95.6%) and Claude Fable 5 (95.0%): pooled SEM across those rows is about 1.3 points and every gap is smaller than that.
Cheapest of the 95%-plus cluster on measured cost per test at $0.40, against $1.15 for Sol and $2.05 for Fable 5. Repriced Aug 1, 2026: OpenAI cut Terra 20% on Jul 30, 2026, from $2.50/$15 to $2/$12 per 1M (vendor-announced, reported by BleepingComputer and VentureBeat). Cached input $0.25 at launch, not re-confirmed after the cut. Context ~1.05M, max output 128k. Released Jul 9, 2026.
what does GPT-5.6 Terra cost?
$2 per 1M input tokens and $12 per 1M output — #17 cheapest of the 27 models we track. Coding workloads are output-heavy, so weight the output rate when budgeting. Run your own volume through the AI API cost calculator for a monthly estimate.
where can you use it?
Available via API · OpenAI platform. As a proprietary model, you're on the maker's infrastructure and release schedule.
head-to-head
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Ranked on our AI Coding Leaderboard — scores confirmed against primary sources only, updated 2026-09-03.