GPT-5 mini vs OpenAI o4-mini
GPT-5 mini is cheaper for every workload modelled here.
List prices checked
Specifications and rates
| Property | GPT-5 mini | OpenAI o4-mini |
|---|---|---|
| Input per 1M | $0.250 | $1.10 |
| Output per 1M | $2.00 | $4.40 |
| Cached input per 1M | $0.025 | $0.275 |
| Blended (3:1) | $0.688 | $1.93 |
| Context window | 400K | 200K |
| Max output | 128K | 100K |
| Inputs accepted | text, image | text, image |
Source: OpenAI pricing (May 2026) · OpenAI pricing (May 2026). Published list prices only — committed-use discounts, regional variation, and per-request charges are not included. Not yet independently re-checked against the vendor’s page.
Monthly cost by workload
Identical token volumes through both rate cards. Output-heavy profiles are where the ranking flips.
| Workload | GPT-5 mini | OpenAI o4-mini | Cheaper |
|---|---|---|---|
| In-app chat assistantA support or help assistant handling a few thousand conversations a month, with short prompts and short answers. | $15 | $44 | GPT-5 minisaves $29/mo (66%) |
| RAG over documentsRetrieval-augmented answering where each request stuffs several retrieved passages into the prompt, so input dominates. | $105 | $396 | GPT-5 minisaves $291/mo (73%) |
| Coding agentAn agentic loop that reads files and writes patches, generating heavy output and re-sending large context on every turn. | $300 | $880 | GPT-5 minisaves $580/mo (66%) |
What each one is for
GPT-5 mini
by OpenAI
A fifth of GPT-5's price with the same 400k context window, which makes it the cheapest way to process very long documents without dropping to a small model.
OpenAI o4-mini
by OpenAI
Cheap reasoning, strong on maths and code relative to its price. Same caveat as every reasoning model: budget for the thinking tokens, not just the visible answer.
Common questions
- Is GPT-5 mini or OpenAI o4-mini cheaper in 2026?
- GPT-5 mini, for every workload modelled here. On a blended 3:1 basis it costs $0.688 per million tokens against OpenAI o4-mini's $1.93.
- Which has the larger context window?
- GPT-5 mini, at 400K tokens against 200K. A larger window only helps if you can afford to fill it — the cost of one full-context request is in the table above.
- Which is cheaper for output-heavy work like agents?
- GPT-5 mini, at $2.00 per million output tokens against $4.40. Reasoning tokens bill as output, so for agentic loops this axis usually decides the invoice regardless of what the input rates look like.
- What is not included in these figures?
- Batch-processing discounts, fine-tuning, long-context surcharges above a provider's standard tier, and any enterprise agreement. These are published pay-as-you-go list prices, checked against each provider's own pricing page on the date shown.