GPT-5.1 Mini
openai/gpt-5.1-miniThe volume workhorse of the GPT line, most of the capability at a fifth of the price.
Model overview
Context window
400K
tokens
Input price
—
quoted on request
Output price
—
quoted on request
Weekly volume
—
tokens / week
Open weights
No
API only
Capabilities
5
of 11 tags
Description
GPT-5.1 Mini is a language model from OpenAI. Webparam does not stock this model yet and can source it on request — tell us what you need it for and we will come back with availability and a price. OpenAI’s stated focus is the reference point for frontier capability. The weights are not published, so it is API-only.
Capabilities
- Tool calling
- Calls functions you define and returns their arguments as structured data, the basis of agents.
- JSON mode
- Constrains the response to valid JSON matching a schema you supply.
- Streaming
- Emits tokens as they are generated, so answers appear progressively rather than all at once.
- Vision input
- Accepts images alongside text in the prompt.
- Caching
- Reuses already-processed prompt prefixes across requests, cutting input cost for repeated context.
Strengths & weaknesses
Strengths
- Excellent capability-per-dollar
- Same 400K context as the flagship
- Fast
Weaknesses
- Hard problems still need the flagship
- Closed weights
Pricing
| Rate | Price | Unit |
|---|---|---|
| Input | — quoted on request | — |
| Output | — quoted on request | — |
Prompt caching is supported, so repeated prefixes bill below the listed input rate. This model is not provisioned yet; the rate is quoted on request.
Context window
400Ktokens
covers prompt and response together, so a long input leaves less room for the answer.
Supported features
| Feature | Support |
|---|---|
| Tool calling | Supported |
| JSON mode | Supported |
| Streaming | Supported |
| Vision input | Supported |
| Audio input | Not supported |
| Long context | Not supported |
| Open weights | Not supported |
| Reasoning | Not supported |
| Fine-tunable | Not supported |
| Batch | Not supported |
| Caching | Supported |
Example use cases
Production default
High-volume features
Cost-tiered routing
Related models
Comparison
Compare against anything →| Attribute | GPT-5.1 Mini | GPT-5.1 | Doubao 1.5 Pro |
|---|---|---|---|
| Context window | 400K | 400K | 256K |
| Input price | R0.00 | R0.00 | R0.00 |
| Output price | — not charged | — not charged | — not charged |
| Tool calling | Supported | Supported | Supported |
| JSON mode | Supported | Supported | Supported |
| Vision input | Supported | Supported | Not supported |
| Open weights | Not supported | Not supported | Not supported |
| Prompt caching | Supported | Supported | Supported |
Best value in each row is highlighted. Blank cells are facts the supplier does not publish, not zeroes.
Provider information
View OpenAI →OpenAI · San Francisco, United States · est. 2015
OpenAI set the template the whole industry follows, from GPT's scaling curves to the API-first business model every provider now imitates. Its GPT-5 generation and o-series reasoning models remain the benchmark others measure against, and its developer platform is the most imitated interface in AI.
Recent releases
Documentation
Frequently asked questions
Input is billed at R0.00 per 1M tokens, and there is no separate output charge. Prompt caching bills repeated prefixes below the listed input rate. Every figure on this page is an illustrative placeholder.
No. GPT-5.1 Mini is served through its provider's API only; the weights are not published, so self-hosting is not an option.
Prompt and response share one window: GPT-5.1 Mini accepts up to 400K tokens in total, so a long input leaves less room for the answer. The median across language models is 256K. Recall is strongest well inside the limit. Test at your real prompt depth before relying on the ceiling.
GPT-5.1 is the closest neighbour in the catalogue, with 400K of context at R0.00 per 1M tokens in. Put both in a comparison before wiring a fallback chain, so the trade-off is a decision rather than a default.