GPT-5.3-Codex vs GPT-6.1 Terra
OpenAI · US | OpenAI · US · Updated June 2026
Quick verdict
Both are OpenAI models. GPT-6.1 Terra is the newer, generally stronger default; reach for GPT-5.3-Codex when a specific cost or latency profile matters more than the latest capabilities.
GPT-5.3-Codex and GPT-6.1 Terra are both OpenAI models, so the real question is not which lab to trust but which tier fits your workload and budget. GPT-5.3-Codex is openAI's coding-specialized agent model for autonomous software engineering. GPT-6.1 Terra is openAI's October 26, 2026 mid-tier model - a 1.05M-context, computer-use-capable GPT at $1/$5 per million tokens, half the price of its predecessor. 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-6.1 Terra is about 1.8× cheaper on input ($1/$5 per 1M tokens vs $1.75/$14 per 1M tokens) — modest, but it adds up at steady volume.
- ▸Context window: GPT-6.1 Terra holds 2.6× more — 1.05M tokens (~1,575 pages) vs 400K (~600 pages). But effective recall usually fades long before the advertised ceiling, so the bigger number only helps if the model reasons over it.
- ▸Recency: GPT-6.1 Terra is the newer model by about 9 months (released October 26, 2026), usually meaning fresher training data and capabilities.
Side-by-side specs
| Spec | GPT-5.3-Codex | GPT-6.1 Terra |
|---|---|---|
| Provider | OpenAI (US) | OpenAI (US) |
| Released | February 5, 2026 | October 26, 2026 |
| Context window | 400K (~600 pages) | 1.05M tokens (~1,575 pages) |
| Price (in/out) | $1.75/$14 per 1M tokens | $1/$5 per 1M tokens |
| Open weight? | No — API only | No — API only |
| Modalities | text, code | text, image, code |
| SWE-Bench Verified | Not published | Not published |
| MRCR v2 @ 1M | Not published | Not published |
Who wins what
Dedicated coding agent
GPT-5.3-Codex
GPT-6.1 Terra is comparatively weak here — openAI still positions Sol and Astra as the higher-capability choices for demanding coding problems
CLI and IDE integration
GPT-5.3-Codex
GPT-5.3-Codex lists cLI and IDE integration among its strengths; GPT-6.1 Terra does not.
Autonomous software tasks
GPT-5.3-Codex
GPT-5.3-Codex lists autonomous software tasks among its strengths; GPT-6.1 Terra does not.
$1/$5 per million tokens (cached input $0.05) - half the price of GPT-6.1 Sol and GPT-5.6 Terra
GPT-6.1 Terra
At $1/$5 per 1M tokens it undercuts GPT-5.3-Codex ($1.75/$14 per 1M tokens), and that gap compounds at volume.
Terminal-Bench 4.0 of 50.3% at maximum reasoning effort, versus 21.5% for GPT-5.6 Terra (OpenAI-reported)
GPT-6.1 Terra
OpenAI's October 26, 2026 mid-tier model - a 1.05M-context, computer-use-capable GPT at $1/$5 per million tokens, half the price of its predecessor — and it runs cheaper at $1/$5 per 1M tokens.
1.05M-token context with up to 128K output tokens, plus image input and computer use via the Responses API
GPT-6.1 Terra
Its 1.05M tokens window holds about 2.6× more than GPT-5.3-Codex's 400K in a single prompt.
Lowest cost at scale
GPT-6.1 Terra
At $1/$5 per 1M tokens, it is the cheaper of the two — the gap dominates the bill on high-volume workloads.
Largest single-prompt input
GPT-6.1 Terra
Its 1.05M tokens window is about 2.6× larger than GPT-5.3-Codex's 400K, fitting roughly 1,575 pages in one prompt.
Which should you pick?
A cost-sensitive startup shipping high volume
→ GPT-6.1 Terra
At $1/$5 per 1M tokens it undercuts GPT-5.3-Codex, and on millions of tokens that margin decides the monthly bill.
Someone analysing very long documents or codebases
→ GPT-6.1 Terra
Larger 1.05M tokens window fits more in one prompt.
Anyone whose priority is dedicated coding agent
→ GPT-5.3-Codex
It is specifically built for that.
Anyone whose priority is $1/$5 per million tokens (cached input $0.05) - half the price of gpt-6.1 sol and gpt-5.6 terra
→ GPT-6.1 Terra
That is its strongest area.
GPT-5.3-Codex: where it fits
OpenAI's coding-specialized agent model for autonomous software engineering. Released February 5, 2026 by OpenAI, it is built for dedicated coding agent, cLI and IDE integration, autonomous software tasks, and tool calling.
Its trade-offs are real: coding-specialized, narrower general use, and retired in favor of GPT-5.5 Codex. At $1.75 in / $14 out per million tokens, it sits in the mid price band.
GPT-6.1 Terra: where it fits
OpenAI's October 26, 2026 mid-tier model - a 1.05M-context, computer-use-capable GPT at $1/$5 per million tokens, half the price of its predecessor. Released October 26, 2026 by OpenAI, it is built for $1/$5 per million tokens (cached input $0.05) - half the price of GPT-6.1 Sol and GPT-5.6 Terra, terminal-Bench 4.0 of 50.3% at maximum reasoning effort, versus 21.5% for GPT-5.6 Terra (OpenAI-reported), 1.05M-token context with up to 128K output tokens, plus image input and computer use via the Responses API, and error rate on OpenAI's hard-prompt set falls from 53.6% (GPT-5.6 Terra) to 16.7% at low effort and 4.3% at max effort.
Its trade-offs: openAI still positions Sol and Astra as the higher-capability choices for demanding coding problems, requests above 272K input tokens are billed at 2x input and 1.5x output for the whole request, closed weights and no fine-tuning support, and benchmark figures are vendor-reported; no SWE-bench Verified or MRCR numbers published. At $1 in / $5 out per million tokens, it sits in the budget price band.
The bottom line for this matchup
Because GPT-5.3-Codex and GPT-6.1 Terra come from the same lab (OpenAI), they share the same training philosophy and ecosystem — the decision is purely tier vs. cost. GPT-6.1 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-6.1 Terra and drop down only with a concrete reason.
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See pricingFrequently asked questions
Is GPT-5.3-Codex or GPT-6.1 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-5.3-Codex leans toward dedicated coding agent while GPT-6.1 Terra leans toward $1/$5 per million tokens (cached input $0.05) - half the price of gpt-6.1 sol and gpt-5.6 terra, and that positioning usually predicts which feels better on your codebase.
Which is cheaper, GPT-5.3-Codex or GPT-6.1 Terra?
GPT-6.1 Terra is cheaper — $1.75/$14 per 1M tokens vs $1/$5 per 1M tokens, roughly 1.8× apart on input.
Which has the bigger context window?
GPT-6.1 Terra — 1.05M tokens vs 400K, about 2.6× larger. Useful only if the model actually reasons over the full window, which not all do.
Should I upgrade from GPT-5.3-Codex to GPT-6.1 Terra?
Since both are OpenAI models, the newer one (GPT-6.1 Terra) is usually the better default unless you need a specific cost or latency profile from the other.
Which is newer, GPT-5.3-Codex or GPT-6.1 Terra?
GPT-6.1 Terra — released October 26, 2026, about 9 months after GPT-5.3-Codex.
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.