Monthly cost at list price for five common workloads. Token counts per unit are stated so you can scale them to your own traffic. A workload that does not fit a model's context window is marked rather than priced.
Workload (per month)
AionLabs: Aion 3.5
OpenAI: GPT-4o
Difference
Customer-support chatbot
50,000 conversations — each a 6-turn conversation (1,500 in / 400 out tokens)
$345
$388
AionLabs: Aion 3.5 saves $42.50
RAG search over documents
20,000 questions — each a question answered from ~8 retrieved passages (6,000 in / 500 out tokens)
$420
$400
OpenAI: GPT-4o saves $20.00
Coding / tool-using agent
2,000 tasks — each a multi-step task with tool calls and file context (60,000 in / 6,000 out tokens)
$432
$420
OpenAI: GPT-4o saves $12.00
Batch summarisation
10,000 documents — each a 6,000-word report summarised to a page (8,000 in / 600 out tokens)
$276
$260
OpenAI: GPT-4o saves $16.00
Long-document analysis
500 documents — each a 150-page contract or codebase read in one pass (100,000 in / 2,000 out tokens)
$156
$135
OpenAI: GPT-4o saves $21.00
Capabilities side by side
Capability
AionLabs: Aion 3.5
OpenAI: GPT-4o
What it lets you do
Tool / function calling
✓ Yes
✓ Yes
call your APIs and run agent loops
Structured output (JSON schema)
✓ Yes
✓ Yes
return JSON that validates against your schema
Reasoning / thinking mode
✓ Yes
—
spend extra tokens thinking before answering hard problems
Image input
—
✓ Yes
read screenshots, charts and scanned pages
Audio input
—
—
take speech or audio directly
File / PDF input
—
✓ Yes
accept documents without your own parsing step
Image output
—
—
generate images, not just text
Built-in web search
—
✓ Yes
answer from live web results
Seed (reproducible sampling)
—
✓ Yes
repeat a generation for tests and evals
Log-probabilities
—
✓ Yes
read token confidence for classification and scoring
From each model's published parameters and input/output types. “—” means not advertised, not proven absent.
Price history
AionLabs: Aion 3.5: price unchanged since we started tracking it on 2026-09-24.
OpenAI: GPT-4o: price unchanged since we started tracking it on 2026-03-10.
Which should you choose?
Choose AionLabs: Aion 3.5 if…
cost matters at scale — it is 14% cheaper on a typical 3:1 input/output mix ($345 vs $388 a month for 50,000 support chats)
you need to fit long inputs in one request — 262K tokens is roughly 393 pages, against 192
you need reasoning / thinking mode — to spend extra tokens thinking before answering hard problems; OpenAI: GPT-4o does not advertise it
you generate long outputs in one go — up to 33K tokens (about 24,600 words) per response
you want the newer model — released 2026-09-23, 29 months after the other
Choose OpenAI: GPT-4o if…
you need image input — to read screenshots, charts and scanned pages; AionLabs: Aion 3.5 does not advertise it
you need file / PDF input — to accept documents without your own parsing step; AionLabs: Aion 3.5 does not advertise it
you need built-in web search — to answer from live web results; AionLabs: Aion 3.5 does not advertise it
you need seed (reproducible sampling) — to repeat a generation for tests and evals; AionLabs: Aion 3.5 does not advertise it
you need log-probabilities — to read token confidence for classification and scoring; AionLabs: Aion 3.5 does not advertise it
Frequently asked questions
Is AionLabs: Aion 3.5 better than OpenAI: GPT-4o?
Neither wins outright: AionLabs: Aion 3.5 is the pick when cost matters at scale, OpenAI: GPT-4o when you need image input. In short: AionLabs: Aion 3.5 when cost matters at scale, you need to fit long inputs in one request, you need reasoning / thinking mode, you generate long outputs in one go, you want the newer model; OpenAI: GPT-4o when you need image input, you need file / PDF input, you need built-in web search, you need seed (reproducible sampling), you need log-probabilities.
Which is cheaper, AionLabs: Aion 3.5 or OpenAI: GPT-4o?
AionLabs: Aion 3.5 is cheaper: $3.75 vs $4.38 per 1M tokens at a typical 3:1 input/output mix, 14% less. For 50,000 support conversations a month that is $345 against $388.
How much do AionLabs: Aion 3.5 and OpenAI: GPT-4o cost per million tokens?
AionLabs: Aion 3.5 costs $3.00 per 1M input tokens and $6.00 per 1M output tokens; OpenAI: GPT-4o costs $2.50 input and $10.00 output. Output tokens are billed separately, so long answers shift the gap.
Which has the bigger context window, AionLabs: Aion 3.5 or OpenAI: GPT-4o?
AionLabs: Aion 3.5: 262K tokens, about 393 pages, against 128K (about 192 pages) for OpenAI: GPT-4o.
Do AionLabs: Aion 3.5 and OpenAI: GPT-4o support function calling and JSON output?
Aion 3.5 is a multi-model roleplaying and storytelling system from AionLabs, built on the GLM family of models. It uses a collaborative generation process in which multiple specialized models each...
GPT-4o ("o" for "omni") is OpenAI's latest AI model, supporting both text and image inputs with text outputs. It maintains the intelligence level of [GPT-4 Turbo](/models/openai/gpt-4-turbo) while being twice as...