GPT-5.6 Terra
OpenAI · Released Jun 2026
The mid-tier GPT-5.6 workhorse — GPT-5.5-class capability at half the cost ($2.50/$15 per 1M tokens), with TerminalBench 2.1 at 84.3% tying Claude Fable 5. The caveat: all claims are vendor-reported, Terra is government-gated to ~20 partners, and GA has no confirmed date. For most production workloads Terra would be the pragmatic default once available; GPT-5.5 and Opus 4.8 are the fallbacks today.
Is it right for you?
Good for
- Cost-efficiency sweet spot: GPT-5.5-class capability at half the price. At $2.50/$15 per 1M tokens, Terra is priced to replace GPT-5.5 as the default model for most production workloads — if the quality claim holds.
- TerminalBench 2.1 at 84.3% ties Claude Fable 5 — Anthropic's publicly available flagship — at the same score. For agentic coding that doesn't need Sol's extreme reasoning depth, Terra is the rational pick.
- High-volume enterprise workloads: customer support, internal tools, document analysis, and production pipelines where reliability matters but per-request cost needs to scale.
- Strong cybersecurity capability for its tier: scored 91.84% on internal CTF testing. Carries activation classifiers and the same safety stack as Sol for regulated cyber and bio workflows.
Not good for
- Government-gated limited preview: same access restrictions as Sol — only ~20 trusted partners today. Claims of 'GPT-5.5 performance at half cost' are vendor-reported, not independently verifiable.
- No ultra or max reasoning modes: Terra lacks the subagent decomposition and extended deliberation that distinguish Sol. For the hardest agentic work, you still need Sol.
- The 84.3% TerminalBench score is only 0.9 points ahead of GPT-5.5 at 83.4%. The 'competitive with GPT-5.5' claim is directionally right but the gap is small — your own evals will tell you more than the scoreboard.
How it performs by task
Agentic coding (mid-tier)
84.3% on TerminalBench 2.1 ties Claude Fable 5. Strong enough for most production coding agents. Sol is the upgrade for the hardest problems.
Cybersecurity
CTF score of 91.84%. Robust security capabilities with activation classifiers. Good for defensive workflows and vulnerability analysis without Sol's premium.
Cost-efficient production workloads
At $2.50/$15 per 1M, Terra is the best cost-to-capability ratio in the GPT-5.6 family. OpenAI's claim of GPT-5.5 performance at half cost is the most commercially important headline for most teams.
General reasoning and everyday work
Pitched as the balanced everyday model. For routine reasoning, writing, analysis, and business intelligence, Terra should be indistinguishable from Sol in quality.
Deep research and hard reasoning
Lacks Sol's max reasoning and ultra subagent modes. Falls behind Sol, Mythos 5, and Fable 5 on the hardest problems. Route hard tasks to Sol, not Terra.
Pricing
Input
$2.50 / 1M tokens
Output
$15 / 1M tokens
Context
Roughly 2x cheaper than GPT-5.5 for similar perf.
Benchmarks
Verdict history
Sources
Verification log
- Pricing— No changes
Automated agent
- Pricing— No changes
Automated agent
- Status— Updated
Automated agent
Summary re-dated to Jul 7 2026 and made explicit about what is awaited: stays pending pending GA + independent benchmarks; still government-gated (~20 orgs); family trending toward release (Sol Ultra confirmed for Codex Jul 6, ~Jul 9 GA per prediction markets, unconfirmed). Verdict unchanged (pending).
- Pricing— No changes
Automated agent
- Pricing— No changes
Automated agent
Pricing unchanged: $2.50/$15 per 1M tokens. Government-gated. Confirmed by OpenAI blog (GPT-5.5-class at half cost).
- Profile— No changes
Imported at launch
- Pricing— No changes
Imported at launch