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Head-to-head comparison

GPT-4 Turbo vs GPT-5.6 Terra

GPT-4 Turbo (OpenAI) and GPT-5.6 Terra (OpenAI) compared on the ModelCap Index, API price, context window, provider availability, weight access and every public benchmark board they share. Figures are the same ones shown on the live rankings; nothing here is a hidden score.

Snapshot as of 22 September 2026

As of 22 September 2026, GPT-5.6 Terra holds the stronger ModelCap Index position (#21 vs #170); GPT-5.6 Terra is 2.5× cheaper per output token ($12.00/1M vs $30.00/1M); and GPT-5.6 Terra offers the longer context window (1M vs 128K tokens).

Which should you choose?

Choose GPT-4 Turbo if…

  • ModelCap publishes no field on which GPT-4 Turbo leads GPT-5.6 Terra for this pair.

Choose GPT-5.6 Terra if…

  • you want the stronger overall ModelCap Index position — #21 against #170 (79.7 vs 30.9 points).
  • API cost matters — $12.00/1M output tokens against $30.00/1M, about 2.5× cheaper.
  • your workload is prompt-heavy — input tokens cost $2.00/1M against $10.00/1M.
  • you need the longer context window — 1M tokens against 128K.
  • you want provider choice — 3 listed API providers against 1.
  • Arena coding is your yardstick — 1518 against 1347.
  • AA Humanity's Last Exam is your yardstick — 42.9% against 3.1%.
  • you want the more recently listed model — GPT-5.6 Terra was listed 9 July 2026, GPT-4 Turbo 9 April 2024.

GPT-4 Turbo vs GPT-5.6 Terra: specs, pricing and context

Specification comparison of GPT-4 Turbo and GPT-5.6 Terra
FieldGPT-4 TurboOpenAIGPT-5.6 TerraOpenAI
ModelCap Index position#170#21
Index score30.979.7
EvidenceMeasuredMeasured
Input price / 1M tokens$10.00$2.00
Output price / 1M tokens$30.00$12.00
Context window128K tokens1M tokens
Max output tokens4K128K
API providers listed13
Weight accessAPI onlyAPI only
Input modalitiesText, ImageFile, Image, Text
First listed9 April 20249 July 2026
PublisherOpenAIOpenAI

Evidence: 2 public benchmark observations across 2 boards · 6 public benchmark observations across 6 boards. Prices are the lowest listed API offer per million tokens observed on the OpenRouter catalogue.

Benchmark scores: GPT-4 Turbo vs GPT-5.6 Terra

Public benchmark boards where GPT-4 Turbo or GPT-5.6 Terra has a published result
BoardGPT-4 TurboGPT-5.6 TerraLeads
Arena codingArena (LMArena)13471340–135415181510–1525X-HighGPT-5.6 Terra
LMArena AgentLMArena—1.4%0.3%–2.6%X-HighOnly one result
ARC-AGI-2ARC Prize Foundation—83.9%MaxOnly one result
ARC-AGI-3ARC Prize Foundation—0.8%MaxOnly one result
AA Intelligence IndexArtificial Analysis—42.1intelligence-index:v4.3:maxOnly one result
AA τ²-Bench TelecomArtificial Analysis—86.3%tau2:telecom:dual-control:pass-at-1:3-repeats:source-model="GPT-5.6 Terra (max)":reasoning=trueOnly one result
AA Humanity's Last ExamArtificial Analysis3.1%hle:may-2025:text-only-2158:no-tools:pass-at-1:source-model="GPT-4 Turbo":reasoning=false42.9%hle:may-2025:text-only-2158:no-tools:pass-at-1:source-model="GPT-5.6 Terra (max)":reasoning=trueGPT-5.6 Terra
Terminal-Bench 4.0Terminal-Bench (Laude Institute)—21.5%18.3%–24.8%Codex · MaxOnly one result

Scores are the sources' own published figures for each model's best evaluated configuration; ModelCap never re-runs a benchmark.

Want a different pairing? Open the interactive comparison tool to swap either model for any current ranked language model.

GPT-4 Turbo vs GPT-5.6 Terra: common questions

Is GPT-4 Turbo better than GPT-5.6 Terra?

GPT-5.6 Terra ranks higher on the ModelCap Index as of 22 September 2026: #21 against #170. That is a capability ranking built from public benchmark evidence with published uncertainty; whether it is "better" for you also depends on price, context and where you can run it. Their published uncertainty intervals do not overlap, but the aggregate Index does not predict performance on every task; compare the relevant benchmark configurations before choosing.

Is GPT-4 Turbo cheaper than GPT-5.6 Terra?

GPT-5.6 Terra is cheaper on output tokens: $12.00/1M against $30.00/1M. Input tokens are $10.00/1M for GPT-4 Turbo and $2.00/1M for GPT-5.6 Terra. Prices are the lowest listed API offer ModelCap observed, in USD per million tokens. For 1,000 requests with 2,000 input and 500 output tokens each (2M input + 0.5M output), the listed-rate estimate is $35.00 for GPT-4 Turbo versus $10.00 for GPT-5.6 Terra. GPT-5.6 Terra costs 71.4% less in this scenario. This excludes caching, batch discounts, prompt-length tiers, tool charges and retries; verify the selected endpoint before budgeting.

Which has the bigger context window, GPT-4 Turbo or GPT-5.6 Terra?

GPT-5.6 Terra has the larger context window: 1M tokens against 128K.

Which is better for coding, GPT-4 Turbo or GPT-5.6 Terra?

Arena coding: GPT-4 Turbo 1347, GPT-5.6 Terra 1518 — GPT-5.6 Terra leads.

Are GPT-4 Turbo and GPT-5.6 Terra open-weight models?

GPT-4 Turbo: API only. GPT-5.6 Terra: API only. Open weights mean the checkpoint can be downloaded and self-hosted under its licence; API-only models are available solely through hosted endpoints.

Where can I run GPT-4 Turbo and GPT-5.6 Terra?

ModelCap currently lists 1 API provider for GPT-4 Turbo and 3 for GPT-5.6 Terra, from the OpenRouter catalogue snapshot the site serves; each model page lists the providers and their prices.

How current is this GPT-4 Turbo vs GPT-5.6 Terra comparison?

Every figure comes from the sealed ModelCap dataset published 22 September 2026; the page re-renders within a minute of each data refresh, and the ModelCap Index positions are the same ones shown on the live rankings.

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