Pick GPT-5.6 Terra for balanced everyday work at roughly half of sol's price or competitive with gpt-5.5 quality at about 2x lower cost. Pick Grok 4.5 for cheap, token-efficient agentic coding — about gpt-5.5-codex quality at roughly half the cost or extreme token efficiency — around 4x fewer output tokens per task than opus 4.8. On a tight budget at scale, Grok 4.5 is the value pick.
GPT-5.6 Terra (OpenAI) and Grok 4.5 (xAI) are two of the models people most often weigh against each other in 2026. 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. Grok 4.5 is xAI's first coding-focused model — pitched as Opus-class but faster, more token-efficient, and cheaper, undercutting GPT-5.5-Codex. They diverge most on price and context window — each quantified below from the models' real specs.
Key differences
Price: nearly identical — $2.5/$15 per 1M tokens vs $2/$6 per 1M tokens. Cost will not be the deciding factor here.
Context window: GPT-5.6 Terra holds 2× more — 1M (~1,500 pages) vs 500K (~750 pages). But effective recall usually fades long before the advertised ceiling, so the bigger number only helps if the model reasons over it.
Specifications
Spec
GPT-5.6 Terra
Grok 4.5
Provider
OpenAI (US)
xAI (US)
Released
July 9, 2026
July 8, 2026
Context window
1M (~1,500 pages)
500K (~750 pages)
Price (in/out)
$2.5/$15 per 1M tokens
$2/$6 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
Balanced everyday work at roughly half of Sol's price: GPT-5.6 Terra — A core design strength of GPT-5.6 Terra.
Competitive with GPT-5.5 quality at about 2x lower cost: GPT-5.6 Terra — A core design strength of GPT-5.6 Terra.
Solid agentic coding (Terminal-Bench 2.1 in the mid-80s): GPT-5.6 Terra — A core design strength of GPT-5.6 Terra.
Cheap, token-efficient agentic coding — about GPT-5.5-Codex quality at roughly half the cost: Grok 4.5 — A core design strength of Grok 4.5.
Extreme token efficiency — around 4x fewer output tokens per task than Opus 4.8: Grok 4.5 — A core design strength of Grok 4.5.
In-IDE coding, trained on real Cursor developer sessions and shipped natively in Cursor: Grok 4.5 — A core design strength of Grok 4.5.
Lowest cost at scale: Grok 4.5 — At $2/$6 per 1M tokens, it is the cheaper of the two — the gap dominates the bill on high-volume workloads.
Largest single-prompt input: GPT-5.6 Terra — Its 1M window is about 2× larger, fitting roughly 1,500 pages in one prompt.
Which should you pick?
A cost-sensitive startup shipping high volume: Grok 4.5 — At $2/$6 per 1M tokens it undercuts GPT-5.6 Terra, and on millions of tokens that margin decides the monthly bill.
Someone analysing very long documents or codebases: GPT-5.6 Terra — Larger 1M window fits more in one prompt.
Anyone whose priority is balanced everyday work at roughly half of sol's price: GPT-5.6 Terra — It is specifically built for that.
Anyone whose priority is cheap, token-efficient agentic coding — about gpt-5.5-codex quality at roughly half the cost: Grok 4.5 — That is its strongest area.
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 are real: 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.
Grok 4.5: where it fits
XAI's first coding-focused model — pitched as Opus-class but faster, more token-efficient, and cheaper, undercutting GPT-5.5-Codex. Released July 8, 2026 by xAI, it is built for cheap, token-efficient agentic coding — about GPT-5.5-Codex quality at roughly half the cost, extreme token efficiency — around 4x fewer output tokens per task than Opus 4.8, in-IDE coding, trained on real Cursor developer sessions and shipped natively in Cursor, and top-tier placement on the Artificial Analysis Intelligence Index.
Its trade-offs: smaller 500K context (halved from the 1M generation), with pricing that doubles above 200K tokens, and eU launch delayed; no open weights. At $2 in / $6 out per million tokens, it sits in the mid price band.
The bottom line for this matchup
GPT-5.6 Terra and Grok 4.5 overlap enough that the right pick depends on your specific job. Grok 4.5 costs less per token; GPT-5.6 Terra holds the larger context; and each leads in its own area — GPT-5.6 Terra for balanced everyday work at roughly half of sol's price, Grok 4.5 for cheap, token-efficient agentic coding — about gpt-5.5-codex quality at roughly half the cost. Rather than crowning one, run the same hard task through both once and let the results decide.
Frequently asked questions
Is GPT-5.6 Terra or Grok 4.5 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-5.6 Terra leans toward balanced everyday work at roughly half of sol's price while Grok 4.5 leans toward cheap, token-efficient agentic coding — about gpt-5.5-codex quality at roughly half the cost, and that positioning usually predicts which feels better on your codebase.
Which is cheaper, GPT-5.6 Terra or Grok 4.5?
Grok 4.5 is cheaper — $2.5/$15 per 1M tokens vs $2/$6 per 1M tokens, roughly 1.3× apart on input.
Which has the bigger context window?
GPT-5.6 Terra — 1M vs 500K, about 2× larger. Useful only if the model actually reasons over the full window, which not all do.
Can I use both GPT-5.6 Terra and Grok 4.5 together?
Yes — a multi-model platform like LumiChats gives you GPT-5.6 Terra, Grok 4.5 and 40+ others under one ₹69/day pass (about $1/day), so you can draft with one and cross-check with the other instead of buying two subscriptions.
Which is newer, GPT-5.6 Terra or Grok 4.5?
GPT-5.6 Terra — released July 9, 2026, about 1 days after Grok 4.5.
GPT-5.6 Terra vs Grok 4.5
OpenAI · US | xAI · US · Updated June 2026
Quick verdict
Pick GPT-5.6 Terra for balanced everyday work at roughly half of sol's price or competitive with gpt-5.5 quality at about 2x lower cost. Pick Grok 4.5 for cheap, token-efficient agentic coding — about gpt-5.5-codex quality at roughly half the cost or extreme token efficiency — around 4x fewer output tokens per task than opus 4.8. On a tight budget at scale, Grok 4.5 is the value pick.
GPT-5.6 Terra (OpenAI) and Grok 4.5 (xAI) are two of the models people most often weigh against each other in 2026. 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. Grok 4.5 is xAI's first coding-focused model — pitched as Opus-class but faster, more token-efficient, and cheaper, undercutting GPT-5.5-Codex. They diverge most on price and context window — each quantified below from the models' real specs.
Key differences at a glance
▸Price: nearly identical — $2.5/$15 per 1M tokens vs $2/$6 per 1M tokens. Cost will not be the deciding factor here.
▸Context window: GPT-5.6 Terra holds 2× more — 1M (~1,500 pages) vs 500K (~750 pages). But effective recall usually fades long before the advertised ceiling, so the bigger number only helps if the model reasons over it.
Side-by-side specs
Spec
GPT-5.6 Terra
Grok 4.5
Provider
OpenAI (US)
xAI (US)
Released
July 9, 2026
July 8, 2026
Context window
1M (~1,500 pages)
500K (~750 pages)
Price (in/out)
$2.5/$15 per 1M tokens
$2/$6 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
Balanced everyday work at roughly half of Sol's price
GPT-5.6 Terra
A core design strength of GPT-5.6 Terra.
Competitive with GPT-5.5 quality at about 2x lower cost
GPT-5.6 Terra
A core design strength of GPT-5.6 Terra.
Solid agentic coding (Terminal-Bench 2.1 in the mid-80s)
GPT-5.6 Terra
A core design strength of GPT-5.6 Terra.
Cheap, token-efficient agentic coding — about GPT-5.5-Codex quality at roughly half the cost
Grok 4.5
A core design strength of Grok 4.5.
Extreme token efficiency — around 4x fewer output tokens per task than Opus 4.8
Grok 4.5
A core design strength of Grok 4.5.
In-IDE coding, trained on real Cursor developer sessions and shipped natively in Cursor
Grok 4.5
A core design strength of Grok 4.5.
Lowest cost at scale
Grok 4.5
At $2/$6 per 1M tokens, it is the cheaper of the two — the gap dominates the bill on high-volume workloads.
Largest single-prompt input
GPT-5.6 Terra
Its 1M window is about 2× larger, fitting roughly 1,500 pages in one prompt.
Which should you pick?
A cost-sensitive startup shipping high volume
→ Grok 4.5
At $2/$6 per 1M tokens it undercuts GPT-5.6 Terra, and on millions of tokens that margin decides the monthly bill.
Someone analysing very long documents or codebases
→ GPT-5.6 Terra
Larger 1M window fits more in one prompt.
Anyone whose priority is balanced everyday work at roughly half of sol's price
→ GPT-5.6 Terra
It is specifically built for that.
Anyone whose priority is cheap, token-efficient agentic coding — about gpt-5.5-codex quality at roughly half the cost
→ Grok 4.5
That is its strongest area.
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 are real: 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.
Grok 4.5: where it fits
XAI's first coding-focused model — pitched as Opus-class but faster, more token-efficient, and cheaper, undercutting GPT-5.5-Codex. Released July 8, 2026 by xAI, it is built for cheap, token-efficient agentic coding — about GPT-5.5-Codex quality at roughly half the cost, extreme token efficiency — around 4x fewer output tokens per task than Opus 4.8, in-IDE coding, trained on real Cursor developer sessions and shipped natively in Cursor, and top-tier placement on the Artificial Analysis Intelligence Index.
Its trade-offs: smaller 500K context (halved from the 1M generation), with pricing that doubles above 200K tokens, and eU launch delayed; no open weights. At $2 in / $6 out per million tokens, it sits in the mid price band.
The bottom line for this matchup
GPT-5.6 Terra and Grok 4.5 overlap enough that the right pick depends on your specific job. Grok 4.5 costs less per token; GPT-5.6 Terra holds the larger context; and each leads in its own area — GPT-5.6 Terra for balanced everyday work at roughly half of sol's price, Grok 4.5 for cheap, token-efficient agentic coding — about gpt-5.5-codex quality at roughly half the cost. Rather than crowning one, run the same hard task through both once and let the results decide.
Want both GPT-5.6 Terra and Grok 4.5 without two subscriptions? LumiChats gives you these plus 40+ models under one ₹69/day pass (about $1/day) — draft with one, cross-check with the other.
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-5.6 Terra leans toward balanced everyday work at roughly half of sol's price while Grok 4.5 leans toward cheap, token-efficient agentic coding — about gpt-5.5-codex quality at roughly half the cost, and that positioning usually predicts which feels better on your codebase.
Which is cheaper, GPT-5.6 Terra or Grok 4.5?
Grok 4.5 is cheaper — $2.5/$15 per 1M tokens vs $2/$6 per 1M tokens, roughly 1.3× apart on input.
Which has the bigger context window?
GPT-5.6 Terra — 1M vs 500K, about 2× larger. Useful only if the model actually reasons over the full window, which not all do.
Can I use both GPT-5.6 Terra and Grok 4.5 together?
Yes — a multi-model platform like LumiChats gives you GPT-5.6 Terra, Grok 4.5 and 40+ others under one ₹69/day pass (about $1/day), so you can draft with one and cross-check with the other instead of buying two subscriptions.
Which is newer, GPT-5.6 Terra or Grok 4.5?
GPT-5.6 Terra — released July 9, 2026, about 1 days after Grok 4.5.
Specifications and benchmarks reflect publicly reported figures as of June 2026 and may change as providers release updates. Always verify on your own workload.