GPT-5.5 vs GPT-5.6 Terra
OpenAI · US | OpenAI · US · Updated June 2026
Quick verdict
Both are OpenAI models. GPT-5.6 Terra is the newer, generally stronger default; reach for GPT-5.5 when a specific cost or latency profile matters more than the latest capabilities.
GPT-5.5 and GPT-5.6 Terra are both OpenAI models, so the real question is not which lab to trust but which tier fits your workload and budget. GPT-5.5 is openAI's first fully retrained base since GPT-4.5 — the terminal and computer-use champion. GPT-5.6 Terra is the mid-tier daily driver of the GPT-5.6 family — near-flagship quality at about half of Sol's cost. Since both come from the same lab, the comparison below focuses on the tier-and-cost trade-offs that actually separate them.
Key differences at a glance
- ▸Price: GPT-5.6 Terra is about 2× cheaper on input ($2.5/$15 per 1M tokens vs $5/$30 per 1M tokens) — meaningful once you are processing millions of tokens a month.
- ▸Context window: both advertise 1M (~1,500 pages). Tie on paper — test on your own long inputs, since usable recall varies by model.
- ▸Recency: GPT-5.6 Terra is the newer model by about 3 months (released July 9, 2026), usually meaning fresher training data and capabilities.
Side-by-side specs
| Spec | GPT-5.5 | GPT-5.6 Terra |
|---|---|---|
| Provider | OpenAI (US) | OpenAI (US) |
| Released | April 23, 2026 | July 9, 2026 |
| Context window | 1M (~1,500 pages) | 1M (~1,500 pages) |
| Price (in/out) | $5/$30 per 1M tokens | $2.5/$15 per 1M tokens |
| Open weight? | No — API only | No — API only |
| Modalities | text, image, code | text, image, code |
| SWE-Bench Verified | Not published | Not published |
| MRCR v2 @ 1M | Not published | Not published |
Who wins what
Terminal, CLI and computer-use automation
GPT-5.5
GPT-5.5 lists terminal, CLI and computer-use automation among its strengths; GPT-5.6 Terra does not.
Long-horizon tool sequencing
GPT-5.5
GPT-5.5 lists long-horizon tool sequencing among its strengths; GPT-5.6 Terra does not.
Strong agentic coding and reasoning
GPT-5.5
GPT-5.6 Terra is comparatively weak here — fewer independently verified benchmarks than Sol, and trails it across coding evals
Balanced everyday work at roughly half of Sol's price
GPT-5.6 Terra
At $2.5/$15 per 1M tokens it undercuts GPT-5.5 ($5/$30 per 1M tokens), and that gap compounds at volume.
Competitive with GPT-5.5 quality at about 2x lower cost
GPT-5.6 Terra
The mid-tier daily driver of the GPT-5.6 family — near-flagship quality at about half of Sol's cost — and it runs cheaper at $2.5/$15 per 1M tokens.
Solid agentic coding (Terminal-Bench 2.1 in the mid-80s)
GPT-5.6 Terra
GPT-5.5 is comparatively weak here — trails Opus 4.8 on hardest coding benchmarks
Lowest cost at scale
GPT-5.6 Terra
At $2.5/$15 per 1M tokens, it is the cheaper of the two — the gap dominates the bill on high-volume workloads.
Which should you pick?
A cost-sensitive startup shipping high volume
→ GPT-5.6 Terra
At $2.5/$15 per 1M tokens it undercuts GPT-5.5, and on millions of tokens that margin decides the monthly bill.
Anyone whose priority is terminal, cli and computer-use automation
→ GPT-5.5
It is specifically built for that.
Anyone whose priority is balanced everyday work at roughly half of sol's price
→ GPT-5.6 Terra
That is its strongest area.
GPT-5.5: where it fits
OpenAI's first fully retrained base since GPT-4.5 — the terminal and computer-use champion. Released April 23, 2026 by OpenAI, it is built for terminal, CLI and computer-use automation, long-horizon tool sequencing, strong agentic coding and reasoning, and browser-driving agents.
Its trade-offs are real: trails Opus 4.8 on hardest coding benchmarks, and tiered long-context pricing above 272K tokens. At $5 in / $30 out per million tokens, it sits in the premium price band.
GPT-5.6 Terra: where it fits
The mid-tier daily driver of the GPT-5.6 family — near-flagship quality at about half of Sol's cost. Released July 9, 2026 by OpenAI, it is built for balanced everyday work at roughly half of Sol's price, competitive with GPT-5.5 quality at about 2x lower cost, solid agentic coding (Terminal-Bench 2.1 in the mid-80s), and same 1M context and programmatic tool calling as Sol.
Its trade-offs: fewer independently verified benchmarks than Sol, and trails it across coding evals, and no open weights. At $2.5 in / $15 out per million tokens, it sits in the mid price band.
The bottom line for this matchup
Because GPT-5.5 and GPT-5.6 Terra come from the same lab (OpenAI), they share the same training philosophy and ecosystem — the decision is purely tier vs. cost. GPT-5.6 Terra is the more capable, more recent option; the other earns its place only when its price or latency profile fits a specific job better. Most teams should default to GPT-5.6 Terra and drop down only with a concrete reason.
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See pricingFrequently asked questions
Is GPT-5.5 or GPT-5.6 Terra better for coding?
Public SWE-Bench figures are not available for either model, so the honest test is your own repository — run an identical real bug through both. By design, GPT-5.5 leans toward terminal, cli and computer-use automation while GPT-5.6 Terra leans toward balanced everyday work at roughly half of sol's price, and that positioning usually predicts which feels better on your codebase.
Which is cheaper, GPT-5.5 or GPT-5.6 Terra?
GPT-5.6 Terra is cheaper — $5/$30 per 1M tokens vs $2.5/$15 per 1M tokens, roughly 2× apart on input.
Which has the bigger context window?
Both advertise 1M (~1,500 pages). Remember advertised ≠ usable: recall typically degrades before the ceiling.
Should I upgrade from GPT-5.5 to GPT-5.6 Terra?
Since both are OpenAI models, the newer one (GPT-5.6 Terra) is usually the better default unless you need a specific cost or latency profile from the other.
Which is newer, GPT-5.5 or GPT-5.6 Terra?
GPT-5.6 Terra — released July 9, 2026, about 3 months after GPT-5.5.
Related comparisons
Specifications and benchmarks reflect publicly reported figures as of June 2026 and may change as providers release updates. Always verify on your own workload.