The short answer
GPT-5.6 Terra is an OpenAI model priced at $1 per million input tokens and $6 per million output tokens, with a 1M token context window. One standard answer, meaning 1,000 tokens in and 500 tokens out, costs $0.0040. Inside Whizi it costs 4 credits per message and needs the Pro plan or above.
That makes it one of the more expensive models in the catalogue: 22 of the 89 priced models cost more per answer, and 66 cost less.
What GPT-5.6 Terra costs
List rates are what the provider charges per token. The cost of one standard answer is the more useful number, because it prices the same unit of work across every model regardless of how each one is billed.
| Input, per million tokens | $1 |
| Output, per million tokens | $6 |
| One standard answer | $0.0040 |
| One thousand answers | $4.00 |
| Context window | 1M tokens |
| Credits per message in Whizi | 4 |
| Minimum Whizi plan | Pro |
| Rank by cost, of 89 priced models | 67 |
Prices are the published OpenAI rates as carried by OpenRouter, last refreshed 2026-08-08. The full dataset covering all 100 models from 28 providers is the AI model cost index, which is free to reuse with attribution.
What it costs inside Whizi
Whizi meters messages in credits rather than tokens, and GPT-5.6 Terra is charged at 4 credits per message. The cost does not change with the length of your message or the length of the answer, so a one line question and a long document analysis cost the same.
| Plan | Price per month | Monthly credits | Messages on this model |
|---|---|---|---|
| Pro | $29.99, or $19.99 billed yearly | 2,000 | 500 |
| Powerhouse | $49.99, or $34.99 billed yearly | 8,000 | 2,000 |
GPT-5.6 Terra is included from the Pro plan up. Pro is a curated tier rather than everything cheap: one or two current flagships per model family, each fast tier, and the high volume workhorses. See plans and limits.
How it compares on price
Against the cheapest model in the index, Ling-2.6-flash at $0.000025 per answer, GPT-5.6 Terra costs 160 times more. Against the median, GLM 4.6 at $0.0015, it costs 2.7 times more.
Its nearest neighbours from OpenAI:
| Model | One answer | Context | Credits |
|---|---|---|---|
| GPT-5.6 Luna | $0.0004 | 1M | 1 |
| GPT-5.4 Nano | $0.0008 | 400K | 2 |
| GPT-5.4 Mini | $0.0030 | 400K | 4 |
| GPT-5.6 Terra (this page) | $0.0040 | 1M | 4 |
If GPT-5.6 Terra is more model than a given task needs, GPT-5.4 Mini is the cheaper OpenAI option at $0.0030 per answer and 4 credits per message. Routing routine work down a tier is the single biggest thing you can do to make an allowance last.
The context window in practice
GPT-5.6 Terra accepts 1M tokens of context, which is roughly 1600 pages of text. That is well above the median for the priced catalogue.
Advertised context and usable context are not the same thing. Recall tends to degrade before the stated limit is reached, particularly for material in the middle of a long input, so the practical test is to upload a long document and ask about something buried halfway through rather than trusting the number.
The number matters most when you are working from your own files. If a document is too long for the model you picked, switching to a larger-context model in the same conversation carries the thread across, so you are not starting over. See switching models mid-conversation.
- Input $1 and output $6 per million tokens
- $0.0040 for one standard answer, $4.00 for a thousand
- 1M token context window
- 4 credits per message inside Whizi
- Requires the Pro plan or above
- Ranks 67 of 89 priced models by cost per answer
Frequently asked questions
How much does GPT-5.6 Terra cost?
$1 per million input tokens and $6 per million output tokens at list rates, which works out to $0.0040 for one standard answer of 1,000 tokens in and 500 out, or $4.00 for a thousand of them. Inside Whizi it is 4 credits per message on a monthly allowance, rather than metered per token.
Which Whizi plan includes GPT-5.6 Terra?
Pro and above, which is $29.99 per month or $19.99 billed yearly. At 4 credits per message, a Pro allowance of 2,000 credits covers 500 messages on this model if you spend the whole allowance here, and most people mix in a 1 credit model for routine work so it goes further.
What is the context window of GPT-5.6 Terra?
1M tokens, which is roughly 1600 pages of text and sits well above the median for the priced catalogue. Treat that as the ceiling rather than the working figure: recall usually degrades before the stated limit, especially for content in the middle of a long input.
Is GPT-5.6 Terra expensive compared to other models?
It ranks 67 of 89 priced models by cost per answer, so 22 cost more and 66 cost less. The spread across the whole catalogue is about 4800 times from cheapest to priciest, which is far wider than most people assume, so "expensive" only means anything relative to the specific alternative you would otherwise use.