As of August 21, 2026, Grok-4 Fast Reasoning API pricing is $0.20 per million input tokens and $0.50 per million output tokens. A typical 100K-in / 20K-out request costs $0.03. Source: https://docs.x.ai/docs/models
Source: xAI API pricing (https://docs.x.ai/docs/models)
Input $/M
$0.20
Output $/M
$0.50
Blended / 1M
$0.70
100K / 20K request
$0.03
| Context Window | 2M |
|---|---|
| Max Output | 30K tokens |
| Release Date | 2025-08-28 |
| Knowledge Cutoff | N/A |
| License | Proprietary |
| Throughput | 90 tok/s |
| GPQA Diamond | 85.3% |
|---|---|
| SWE-bench Verified | 45.4% |
| LiveCodeBench | 79.0% |
| Arena Code Elo | 1161 |
| Vibe Code Bench | 0% |
| ARC-AGI 2 | 5.3% |
| ARC-AGI-1 Verified | 48.5% |
| Terminal-Bench 2.0 | 29.2% |
| FinanceAgent v1.1 | 46.1% |
| AIME 2025 | 91.3% |
| MMMU | 72.8% |
| CorpFin v2 | 66.9% |
| IOI | 11.5% |
| MedCode | 37.4% |
| MedQA | 92.1% |
| MedScribe | 81.6% |
| MGSM | 90.9% |
| MMLU-Pro | 79.7% |
| SAGE | 29.8% |
| Tax Eval v2 | 75.7% |
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As of August 21, 2026, Grok-4 Fast Reasoning xAI API pricing is $0.20 per million input tokens and $0.50 per million output tokens. Input tokens are the prompt you send; output tokens are the completion. Long answers therefore cost more than short ones even when the prompt stays the same. Source: https://docs.x.ai/docs/models
On this page the blended Grok-4 Fast Reasoning API cost is $0.70 for 1 million input tokens plus 1 million output tokens. That 1:1 mix is the comparison scale used across the LLM pricing table. A 3:1 mix (three million input tokens per one million output tokens), which some calculators use, would be about $1.10.
A typical Grok-4 Fast Reasoning API request with 100K input tokens and 20K output tokens costs about $0.03 at current rates as of August 21, 2026. Multiply that by daily or monthly volume to estimate spend. Caching, batch APIs, and volume discounts from xAI can bring the real invoice lower than the public list rate at https://docs.x.ai/docs/models.
Grok-4 Fast Reasoning supports a 2M token context window and can generate up to 30K output tokens per request. The context window is the total prompt plus conversation history the model can see in one call. Larger windows cost more when you fill them, because every input token is billed per million tokens.
No. Grok-4 Fast Reasoning is a proprietary model by xAI. The only public way to call it is xAI's API, billed per million input and output tokens. There is no self-host option for the weights.
Grok-4 Fast Reasoning currently reports GPQA Diamond 85.3%, SWE-bench Verified 45.4%, LiveCodeBench 79.0%. See the performance table for the full eval set. Use those scores with the token prices above when you are choosing between a cheaper LLM and a frontier model. GPQA, SWE-bench, and HLE are the evals people usually compare first.
Grok-4 Fast Reasoning scores 45.4% on SWE-bench Verified. Pair that score with xAI API pricing on this page: a slightly worse SWE-bench model can still win if it is much cheaper per million tokens. Open the SWE-bench or coding leaderboard from the sidebar for the full ranking, then jump into an LLM comparison against a coding specialist.
Use the Compare picker on this page to start an LLM comparison. Search by model or provider, pick a second model, and AnotherWrapper opens a dedicated Grok-4 Fast Reasoning vs page with per-million-token prices, blended 1M-in / 1M-out cost, context window, throughput, and benchmarks. You can also open any model from the sidebar, or go back to the LLM pricing table to sort the full index.
The cheapest LLM alternative depends on whether you optimize for blended token cost, coding evals, or context window. Start with the popular matchups on this page, then sort the LLM pricing table by blended cost to see which hosted APIs undercut Grok-4 Fast Reasoning. Open-weight models can be cheaper still if you self-host, but that is not the same as xAI API pricing on this page.
Grok-4 Fast Reasoning is called through xAI's API with an API key. Bill against input and output tokens separately; cache or shorten prompts if spend is high. If you are shipping a full product, AnotherWrapper includes pre-built API routes and templates for xAI and 5+ other providers with auth, payments, and deployment already configured.
This Grok-4 Fast Reasoning page tracks the latest published xAI API pricing from xAI, quoted per million tokens. List rates can differ from invoices because of prompt caching, batch discounts, committed-use tiers, and private contracts. Official rate sheet: https://docs.x.ai/docs/models. Benchmark scores come from official publications and independent evals, not from a private lab run by AnotherWrapper.
Grok-4 Fast Reasoning has a measured throughput of about 90 tokens per second (tok/s). Throughput is how fast completions stream once the model starts generating; time-to-first-token can still lag under load. Faster APIs matter when you are building chat or agents, even if the per-million-token price is the same.
Grok-4 Fast Reasoning is a proprietary model from xAI. Current API pricing is $0.20 per million input tokens and $0.50 per million output tokens, with a 2M token context window. A blended 1M-in / 1M-out workload costs $0.70.
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