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Head-to-head comparison

GPT-3.5 Turbo Instruct vs GPT-5.6 Terra

GPT-3.5 Turbo Instruct (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 17 August 2026

As of 17 August 2026, GPT-5.6 Terra holds the stronger ModelCap Index position (#12 vs #107); GPT-3.5 Turbo Instruct is 6× cheaper per output token ($2.00/1M vs $12.00/1M); and GPT-5.6 Terra offers the longer context window (1M vs 4K tokens).

Which should you choose?

Choose GPT-3.5 Turbo Instruct if…

  • API cost matters — $2.00/1M output tokens against $12.00/1M, about 6× cheaper.
  • your workload is prompt-heavy — input tokens cost $1.50/1M against $2.00/1M.

Choose GPT-5.6 Terra if…

  • you want the stronger overall ModelCap Index position — #12 against #107 (73.7 vs 22.5 points).
  • you need the longer context window — 1M tokens against 4K.
  • you want provider choice — 3 listed API providers against 1.
  • you want the more recently listed model — GPT-5.6 Terra was listed 9 July 2026, GPT-3.5 Turbo Instruct 28 September 2023.

GPT-3.5 Turbo Instruct vs GPT-5.6 Terra: specs, pricing and context

Specification comparison of GPT-3.5 Turbo Instruct and GPT-5.6 Terra
FieldGPT-3.5 Turbo InstructOpenAIGPT-5.6 TerraOpenAI
ModelCap Index position#107#12
Index score22.573.7
EvidenceEstimatedMeasured
Input price / 1M tokens$1.50$2.00
Output price / 1M tokens$2.00$12.00
Context window4K tokens1M tokens
Max output tokens4K128K
API providers listed13
Weight accessAPI onlyAPI only
Input modalitiesTextFile, Image, Text
First listed28 September 20239 July 2026
PublisherOpenAIOpenAI

Evidence: publisher corpus prior · leave-one-anchor-out calibrated · 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-3.5 Turbo Instruct vs GPT-5.6 Terra

Public benchmark boards where GPT-3.5 Turbo Instruct or GPT-5.6 Terra has a published result
BoardGPT-3.5 Turbo InstructGPT-5.6 TerraLeads
Arena codingArena (LMArena)—15161506–1525X-HighOnly one result
LMArena AgentLMArena—3.8%2.5%–5.0%X-HighOnly one result
ARC-AGI-2ARC Prize Foundation—83.9%MaxOnly one result
ARC-AGI-3ARC Prize Foundation—0.8%MaxOnly one result
Artificial Analysis Intelligence IndexArtificial Analysis—56.6intelligence-indexOnly 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-3.5 Turbo Instruct vs GPT-5.6 Terra: common questions

Is GPT-3.5 Turbo Instruct better than GPT-5.6 Terra?

GPT-5.6 Terra ranks higher on the ModelCap Index as of 17 August 2026: #12 against #107. 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.

Is GPT-3.5 Turbo Instruct cheaper than GPT-5.6 Terra?

GPT-3.5 Turbo Instruct is cheaper on output tokens: $2.00/1M against $12.00/1M. Input tokens are $1.50/1M for GPT-3.5 Turbo Instruct and $2.00/1M for GPT-5.6 Terra. Prices are the lowest listed API offer ModelCap observed, in USD per million tokens.

Which has the bigger context window, GPT-3.5 Turbo Instruct or GPT-5.6 Terra?

GPT-5.6 Terra has the larger context window: 1M tokens against 4K.

Which is better for coding, GPT-3.5 Turbo Instruct or GPT-5.6 Terra?

The two models do not share a coding benchmark board on ModelCap yet, so no head-to-head coding score is published; the ModelCap Index position is the closest overall signal.

Are GPT-3.5 Turbo Instruct and GPT-5.6 Terra open-weight models?

GPT-3.5 Turbo Instruct: 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-3.5 Turbo Instruct and GPT-5.6 Terra?

ModelCap currently lists 1 API provider for GPT-3.5 Turbo Instruct 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-3.5 Turbo Instruct vs GPT-5.6 Terra comparison?

Every figure comes from the sealed ModelCap dataset published 17 August 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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