As of August 20, 2026, Grok 4 Fast and Grok-4 Fast Non-Reasoning have the same blended API cost at $0.70 per 1 million input plus 1 million output tokens. Grok 4 Fast is $0.20 / $0.50 per million tokens versus Grok-4 Fast Non-Reasoning at $0.20 / $0.50. Source: https://docs.x.ai/docs/models
Source: xAI API pricing (https://docs.x.ai/docs/models)
Grok 4 Fast
xAI
Input
$0.20
Output
$0.50
Grok-4 Fast Non-Reasoning
xAI
Input
$0.20
Output
$0.50
Token pricing, specs, and benchmarks side by side
Grok 4 FastGrok-4 Fast Non-ReasoningVerdict
Grok 4 Fast offers both lower pricing and stronger benchmark performance across the board, making it the clear value leader in this comparison.
As of August 20, 2026, Grok 4 Fast is 0% cheaper on blended LLM API pricing. Grok 4 Fast costs $0.20 per million input tokens and $0.50 per million output tokens ($0.70 blended 1M-in + 1M-out). Grok-4 Fast Non-Reasoning costs $0.20 / $0.50 per million tokens ($0.70 blended). Sources: https://docs.x.ai/docs/models and https://docs.x.ai/docs/models. The cheapest LLM for your app still depends on how many output tokens you generate.
Grok 4 Fast xAI API pricing is $0.20 input and $0.50 output per million tokens via xAI. Grok-4 Fast Non-Reasoning xAI API pricing is $0.20 input and $0.50 output per million tokens via xAI. Use those four numbers, not ChatGPT Plus or Claude Pro subscription prices, when you are comparing APIs.
Grok 4 Fast leads on LiveCodeBench: Grok 4 Fast at 80% vs Grok-4 Fast Non-Reasoning at 46.1%. SWE-bench measures real GitHub fixes; LiveCodeBench measures contest programming.
Grok 4 Fast supports a 2M token context window, while Grok-4 Fast Non-Reasoning supports 2M tokens. Both models have the same context window size. Filling a larger window bills more input tokens, so the cheaper-per-million model can still cost more on long documents.
Grok 4 Fast leads on 2 of 2 shared benchmarks versus Grok-4 Fast Non-Reasoning's 0 wins. Check the comparison table for GPQA Diamond, SWE-bench, MMLU, HLE, and the other evals we track. Token price and benchmark score together are the usual LLM comparison, not either number alone.
Both Grok 4 Fast and Grok-4 Fast Non-Reasoning are production API models. For cost-sensitive production traffic, Grok 4 Fast has better economics on the blended 1M-in + 1M-out scale. For maximum capability, weight the benchmark table for your domain. Many production stacks route cheap models for drafts and a frontier model for the hard turn, which is usually cheaper than sending everything to the expensive API.
Yes. Call Grok 4 Fast through xAI and Grok-4 Fast Non-Reasoning through xAI with separate API keys, or through a gateway that already wraps both. Keep prompts in tokens, not characters, when you estimate the invoice. AnotherWrapper templates can swap providers without rewriting auth and billing.
List rates are the latest published xAI API pricing and xAI API pricing, quoted per million tokens. Official rate sheets: https://docs.x.ai/docs/models and https://docs.x.ai/docs/models. Prompt caching, batch APIs, and committed-use discounts can change the invoice. Benchmark scores are from official publications and independent evals, updated as new numbers land.
Grok 4 Fast supports up to 30K output tokens per request, while Grok-4 Fast Non-Reasoning supports up to 30K output tokens. Output tokens are usually the expensive half of API pricing, so a higher max output cap is a capability, not a discount.
Grok 4 Fast runs at approximately 90 tokens/second while Grok-4 Fast Non-Reasoning runs at 90 tokens/second. Grok-4 Fast Non-Reasoning is faster in raw throughput. Throughput (tokens per second) and time-to-first-token are why two models with the same per-million-token price can still feel different in chat and agents.
Use the model pickers at the top of this LLM comparison. Search any model in the index and the URL updates. Open Grok 4 Fast or Grok-4 Fast Non-Reasoning from the sidebar for the single-model API pricing page, or go back to the LLM pricing table to sort by cheapest blended cost.
This comparison covers API pricing, context window, throughput, and benchmark scores. Grok 4 Fast costs $0.20/M input and $0.50/M output. Grok-4 Fast Non-Reasoning costs $0.20/M input and $0.50/M output.
Rank both on the LLM leaderboard, SWE-bench, and Humanity's Last Exam.
The index
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