Grok 3 mini vs OpenAI o4-mini
Grok 3 mini is cheaper for every workload modelled here.
List prices checked
Specifications and rates
| Property | Grok 3 mini | OpenAI o4-mini |
|---|---|---|
| Input per 1M | $0.300 | $1.10 |
| Output per 1M | $0.500 | $4.40 |
| Cached input per 1M | — | $0.275 |
| Blended (3:1) | $0.350 | $1.93 |
| Context window | 131K | 200K |
| Max output | — | 100K |
| Inputs accepted | text | text, image |
Source: xAI 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 | Grok 3 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. | $8.50 | $44 | Grok 3 minisaves $36/mo (81%) |
| RAG over documentsRetrieval-augmented answering where each request stuffs several retrieved passages into the prompt, so input dominates. | $98 | $396 | Grok 3 minisaves $299/mo (75%) |
| Coding agentAn agentic loop that reads files and writes patches, generating heavy output and re-sending large context on every turn. | $170 | $880 | Grok 3 minisaves $710/mo (81%) |
What each one is for
Grok 3 mini
by xAI
An unusually cheap reasoning model, with output priced below most competitors' input rates — which matters because reasoning models are output-heavy by nature.
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 Grok 3 mini or OpenAI o4-mini cheaper in 2026?
- Grok 3 mini, for every workload modelled here. On a blended 3:1 basis it costs $0.350 per million tokens against OpenAI o4-mini's $1.93.
- Which has the larger context window?
- OpenAI o4-mini, at 200K tokens against 131K. 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?
- Grok 3 mini, at $0.500 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.
- Is switching from OpenAI o4-mini to Grok 3 mini worth it?
- On price alone it is about 82% cheaper on a blended basis. Whether that survives contact with your workload depends on output quality and on retry rate — a cheaper model that needs two attempts is not cheaper. Model the specific volumes in the calculator before you migrate.