Head-to-head comparison

GPT-4o (2024-08-06) vs GPT-5.6 Terra

GPT-4o (2024-08-06) (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 3 September 2026

As of 3 September 2026, GPT-5.6 Terra holds the stronger ModelCap Index position (#13 vs #110); GPT-4o (2024-08-06) is 1.2× cheaper per output token ($10.00/1M vs $12.00/1M); and GPT-5.6 Terra offers the longer context window (1M vs 128K tokens).

Which should you choose?

Choose GPT-4o (2024-08-06) if…

API cost matters — $10.00/1M output tokens against $12.00/1M, about 1.2× cheaper.

Choose GPT-5.6 Terra if…

you want the stronger overall ModelCap Index position — #13 against #110 (74.5 vs 24.2 points).
your workload is prompt-heavy — input tokens cost $2.00/1M against $2.50/1M.
you need the longer context window — 1M tokens against 128K.
you want provider choice — 3 listed API providers against 2.
Arena coding is your yardstick — 1519 against 1360.
AA Intelligence Index is your yardstick — 56.6 against 9.4.
AA τ²-Bench Telecom is your yardstick — 86.3% against 28.9%.
AA Humanity's Last Exam is your yardstick — 42.9% against 2.3%.
you want the more recently listed model — GPT-5.6 Terra was listed 9 July 2026, GPT-4o (2024-08-06) 6 August 2024.

GPT-4o (2024-08-06) vs GPT-5.6 Terra: specs, pricing and context

Specification comparison of GPT-4o (2024-08-06) and GPT-5.6 Terra
Field	GPT-4o (2024-08-06)OpenAI	GPT-5.6 TerraOpenAI
ModelCap Index position	#110	#13
Index score	24.2	74.5
Evidence	Measured	Measured
Input price / 1M tokens	$2.50	$2.00
Output price / 1M tokens	$10.00	$12.00
Context window	128K tokens	1M tokens
Max output tokens	16K	128K
API providers listed	2	3
Weight access	API only	API only
Input modalities	Text, Image, File	File, Image, Text
First listed	6 August 2024	9 July 2026
Publisher	OpenAI	OpenAI

Evidence: 3 public benchmark observations across 3 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-4o (2024-08-06) vs GPT-5.6 Terra

Public benchmark boards where GPT-4o (2024-08-06) or GPT-5.6 Terra has a published result
Board	GPT-4o (2024-08-06)	GPT-5.6 Terra	Leads
Arena codingArena (LMArena)	13601352–1368	15191511–1527X-High	GPT-5.6 Terra
LMArena AgentLMArena	—	2.9%1.7%–4.1%X-High	Only one result
ARC-AGI-2ARC Prize Foundation	—	83.9%Max	Only one result
ARC-AGI-3ARC Prize Foundation	—	0.8%Max	Only one result
AA Intelligence IndexArtificial Analysis	9.4intelligence-index	56.6intelligence-index	GPT-5.6 Terra
AA Terminal-Bench 2.1Artificial Analysis	—	88.0%terminal-bench-2.1	Only one result
AA τ²-Bench TelecomArtificial Analysis	28.9%tau2-bench-telecom	86.3%tau2-bench-telecom	GPT-5.6 Terra
AA Humanity's Last ExamArtificial Analysis	2.3%humanitys-last-exam	42.9%humanitys-last-exam	GPT-5.6 Terra
Terminal-Bench 4.0Terminal-Bench (Laude Institute)	—	21.5%18.3%–24.8%Codex · Max	Only 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-4o (2024-08-06) vs GPT-5.6 Terra: common questions

Is GPT-4o (2024-08-06) better than GPT-5.6 Terra?

GPT-5.6 Terra ranks higher on the ModelCap Index as of 3 September 2026: #13 against #110. 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-4o (2024-08-06) cheaper than GPT-5.6 Terra?

GPT-4o (2024-08-06) is cheaper on output tokens: $10.00/1M against $12.00/1M. Input tokens are $2.50/1M for GPT-4o (2024-08-06) 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-4o (2024-08-06) or GPT-5.6 Terra?

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

Which is better for coding, GPT-4o (2024-08-06) or GPT-5.6 Terra?

Arena coding: GPT-4o (2024-08-06) 1360, GPT-5.6 Terra 1519 — GPT-5.6 Terra leads.

Are GPT-4o (2024-08-06) and GPT-5.6 Terra open-weight models?

GPT-4o (2024-08-06): 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-4o (2024-08-06) and GPT-5.6 Terra?

ModelCap currently lists 2 API providers for GPT-4o (2024-08-06) 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-4o (2024-08-06) vs GPT-5.6 Terra comparison?

Every figure comes from the sealed ModelCap dataset published 3 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.