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AI Choice Engine

Model comparison

GPT-5.6 Sol vs GPT-5.6 Terra

Two OpenAI tiers compared on the figures that decide which one a workload actually needs.

Recorded profile verification October 1, 2026Individual provider fields may changeEvidence confidence: Medium — see receipts below

OpenAI

GPT-5.6 Sol

Frontier

vs

OpenAI

GPT-5.6 Terra

Balanced

AI model capability comparison
SpecificationGPT-5.6 SolGPT-5.6 Terra
ProviderOpenAIOpenAI
TierFrontierBalanced
Context window1.05M1.05M
Max output128K128K
Input / 1M tokens$4Winner: $2
Output / 1M tokens$20Winner: $12
WeightsClosedClosed
ParametersNot verifiedUnverifiedNot verifiedUnverified
Reasoning levelsnone, low, medium, high, xhigh, maxnone, low, medium, high, xhigh, max
Modalitiestext, imagetext, image
API model idgpt-5.6-solgpt-5.6-terra
ReleasedJuly 9, 2026July 9, 2026
Terminal-Bench 2.1 · source date GPT-5.6 Sol: 2026-07-0988.8Not verifiedUnverified
Terminal-Bench 2.1 · source date GPT-5.6 Terra: 2026-07-09Not verifiedUnverified87.4
GPQA Diamond · source date GPT-5.6 Sol: 2026-07-0994.6Not verifiedUnverified
Artificial Analysis Intelligence Index [max] · source date GPT-5.6 Terra: 2026-10-01Not verifiedUnverified42
LiveBench · source date GPT-5.6 Terra: 2026-09-05Not verifiedUnverified77.9

Dates beside benchmark scores refer to the linked source’s publication or capture date unless that source explicitly states when it measured the result. A shared URL alone does not establish comparable runs; unverified setups are marked. Prices are USD per million tokens at standard rates, excluding batch and caching discounts. Values we could not confirm from the provider are shown as “Not verified” rather than estimated.

Benchmark receipts

Where each score comes from, and how far it can be compared across models.

  • Source date2026-10-01
    Artificial Analysis (GPT-5.6 Terra (max))

    Composite index blending reasoning, knowledge, and coding evals into one 0–100 score.

    Comparable with caveatOnly same-version scores are comparable. v4.3.2 was rebaselined (the top score fell from 66 on v4.1.1 to ~58), so v4.1.1 figures must not be compared with v4.3.2 figures — check the cited source and its date.

  • Source date2026-09-05
    LiveBench official leaderboard (benchmark-owned), max effort

    Contamination-resistant general capability across reasoning, coding, math, data analysis, and language, with monthly question refreshes.

    Comparable with caveatCompare only observations confirmed to use the same exact question-set version. Date proximity (including within one month) does not establish identical questions; when the version is unavailable, treat the scores as unaligned.

  • Source date2026-07-09
    OpenAI GPT-5.6 launch table (vendor-reported; effort and experiment date unspecified) (Vendor launch table; complete common run settings unverified)

    Agentic terminal work: multi-step tasks executed in a sandboxed shell environment.

    Comparable with caveatNot comparable with Terminal-Bench 3.0 or 4.0 (different task sets) or v1; harness configuration (container, time limits) also shifts results.

  • Source date2026-07-09
    OpenAI — GPT-5.6 evals table (vendor)

    Graduate-level science reasoning: multiple-choice questions written by domain PhDs.

    Comparable with caveatDo not treat a fixed two-point band as universal measurement uncertainty; it depends on run count and evaluation setup. Chain-of-thought, prompt, and tool policy must match. The small pool limits fine-grained conclusions, and frontier scores can be near ceiling; Artificial Analysis dropped it from its Intelligence Index in v4.3.

  • Source date2026-07-09
    OpenAI — GPT-5.6 evals table (vendor; Ultra multi-agent config: 91.9)

    Agentic terminal work: multi-step tasks executed in a sandboxed shell environment.

    Comparable with caveatNot comparable with Terminal-Bench 3.0 or 4.0 (different task sets) or v1; harness configuration (container, time limits) also shifts results.

Pricing tiers

GPT-5.6 Sol: Launch $5/$30, reduced to promotional $4/$20 on August 21; available at least through November 21, 2026. Above 272K input the full request bills $8/$30. Cached input $0.40/$0.80 short/long and cache writes $5/$10. Batch is $2/$10 at short context. Regional/FedRAMP processing adds 10% where eligible. Knowledge cutoff Feb 16 2026.

GPT-5.6 Terra: Launch $2.50/$15, reduced to $2/$12 on July 30. Above 272K input the full request bills $4/$18. Cached input $0.20; cache writes $2.50 at short context. Batch $1/$6 at short context. Regional/FedRAMP processing adds 10% where eligible.

FrontierRecord checked October 1, 2026

GPT-5.6 Sol

GPT-5.6 Sol was OpenAI's GPT-5.6 flagship for complex reasoning and coding with a 1.05M-token context — superseded on 2026-09-22 by GPT-6 Sol at half the price.

Best for

  • Complex reasoning
  • Agentic coding
  • Hard knowledge work

Watch out

GPT-6.1 Sol is the newer Sol option at $2/$10 Standard. GPT-5.6 Sol remains listed; its $4/$20 price is promotional. Max effort can increase token use, and Ultra is a multi-agent configuration rather than a separate reasoning.effort value.

BalancedRecord checked October 1, 2026

GPT-5.6 Terra

OpenAI’s middle GPT-5.6 tier for balancing intelligence and cost, with text/image input and a 1.05M-token context.

Best for

  • Cost-sensitive production
  • Mixed reasoning workloads
  • High-volume agents

Watch out

GPT-6.1 Sol lists the same $2 input price and a lower $10 output price than Terra’s $12. Compare representative tasks rather than infer quality from token prices or one index. Terra remains listed in the API model catalog.

When the cheaper one wins

GPT-5.6 Terra is cheaper on output at $12 per million tokens against $20 for GPT-5.6 Sol — about 1.7×. Use the cheaper tier for classification, extraction, summarisation, and any task where the expensive model’s extra score does not change the accepted output. The expensive one only pays if your hardest task actually fails on the cheap tier. On DeepSWE 1.1, GPT-5.6 Terra is 69.6% Pass@1 at $4.95/task versus GPT-5.6 Sol at 72.7% / $8.39/task. This compares standard short-context token rates, not total cost per accepted task. Include input, cache, context tiers, schedules, retries and review in your pilot.

Run the model picker

Evidence confidence: Medium

How strong and complete the evidence behind this comparison is — not a prediction of which model is better.

  • Pricing verified on both sides — Input and output rates are verified for both models.
  • 4/5 core specs verified on both sides — Not published for at least one side: parameter count.
  • No directly aligned benchmark setup — No benchmark has matching cited sources, source dates, units, effort and recorded run details on both models.
  • Verified within the last 90 days — Older of the two catalog checks was 25 days ago.
  • Both models carry source citations — Each side has at least two catalog sources on record.

Source receipts

Each catalog figure was checked against the provider or an independent second source on the date shown.

Related comparisons

Diving deeper on one model? GPT-5.6 Sol · GPT-5.6 Terra

Common questions

GPT-5.6 Sol vs GPT-5.6 Terra

Answered from the verified figures on this page rather than general guidance.

Is GPT-5.6 Sol or GPT-5.6 Terra cheaper for input?
GPT-5.6 Terra is cheaper at $2 per million input tokens, against $4 for GPT-5.6 Sol — roughly 2.0× the price. Estimate both input and output token volume for your workload. These are base rates; GPT-5.6 Sol: Launch $5/$30, reduced to promotional $4/$20 on August 21; available at least through November 21, 2026. Above 272K input the full request bills $8/$30. Cached input $0.40/$0.80 short/long and cache writes $5/$10. Batch is $2/$10 at short context. Regional/FedRAMP processing adds 10% where eligible. Knowledge cutoff Feb 16 2026. GPT-5.6 Terra: Launch $2.50/$15, reduced to $2/$12 on July 30. Above 272K input the full request bills $4/$18. Cached input $0.20; cache writes $2.50 at short context. Batch $1/$6 at short context. Regional/FedRAMP processing adds 10% where eligible.
Is GPT-5.6 Sol or GPT-5.6 Terra cheaper for output?
GPT-5.6 Terra is cheaper at $12 per million output tokens, against $20 for GPT-5.6 Sol — roughly 1.7× the price. Estimate both input and output token volume for your workload. These are base rates; GPT-5.6 Sol: Launch $5/$30, reduced to promotional $4/$20 on August 21; available at least through November 21, 2026. Above 272K input the full request bills $8/$30. Cached input $0.40/$0.80 short/long and cache writes $5/$10. Batch is $2/$10 at short context. Regional/FedRAMP processing adds 10% where eligible. Knowledge cutoff Feb 16 2026. GPT-5.6 Terra: Launch $2.50/$15, reduced to $2/$12 on July 30. Above 272K input the full request bills $4/$18. Cached input $0.20; cache writes $2.50 at short context. Batch $1/$6 at short context. Regional/FedRAMP processing adds 10% where eligible.
Which has the larger context window, GPT-5.6 Sol or GPT-5.6 Terra?
Both accept about 1.05M tokens of context, so document length will not decide between them.
Do GPT-5.6 Sol and GPT-5.6 Terra support the same reasoning levels?
Both expose these named effort settings: "none", "low", "medium", "high", "xhigh", "max". The same labels do not guarantee equal compute budgets or behavior across providers. Compare quality, latency and cost on your own tasks.
Should I use GPT-5.6 Sol or GPT-5.6 Terra?
We classify GPT-5.6 Sol in the frontier tier and GPT-5.6 Terra in the balanced tier. Test whether either meets your accuracy, tool-use and latency requirements before choosing on price.

Next step

Choosing between them

The verified figures that separate this pair, computed from the catalog rather than restated boilerplate.

  • Input price: GPT-5.6 Terra costs $2 per 1M tokens versus $4 for GPT-5.6 Sol — a 2x difference at the headline tier.
  • Positioning: GPT-5.6 Sol sits in the frontier tier, GPT-5.6 Terra in the balanced tier. Compare accuracy, reliability, latency, and cost on representative tasks before choosing.
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