As of August 20, 2026, Grok 4 Fast is 45% cheaper per million tokens than DeepSeek-V3.1. DeepSeek-V3.1 is $0.27 / $1.00 per million input/output tokens versus Grok 4 Fast at $0.20 / $0.50. Sources: https://api-docs.deepseek.com/quick_start/pricing and https://docs.x.ai/docs/models
Sources: DeepSeek API pricing (https://api-docs.deepseek.com/quick_start/pricing); xAI API pricing (https://docs.x.ai/docs/models)
DeepSeek-V3.1
DeepSeek
Input
$0.27
Output
$1.00
Grok 4 Fast
xAI
Input
$0.20
Output
$0.50
Token pricing, specs, and benchmarks side by side
DeepSeek-V3.1Grok 4 FastVerdict
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 45% 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). DeepSeek-V3.1 costs $0.27 / $1.00 per million tokens ($1.27 blended). Sources: https://api-docs.deepseek.com/quick_start/pricing and https://docs.x.ai/docs/models. The cheapest LLM for your app still depends on how many output tokens you generate.
DeepSeek-V3.1 DeepSeek API pricing is $0.27 input and $1.00 output per million tokens via DeepSeek. Grok 4 Fast 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.
DeepSeek-V3.1 has a published SWE-bench Verified score of 66%. Grok 4 Fast does not have that eval on this page yet.
DeepSeek-V3.1 supports a 164K token context window, while Grok 4 Fast supports 2M tokens. Grok 4 Fast offers a larger context window. 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 8 of 8 shared benchmarks versus DeepSeek-V3.1'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 DeepSeek-V3.1 and Grok 4 Fast 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 DeepSeek-V3.1 through DeepSeek and Grok 4 Fast 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 DeepSeek API pricing and xAI API pricing, quoted per million tokens. Official rate sheets: https://api-docs.deepseek.com/quick_start/pricing 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.
DeepSeek-V3.1 supports up to 164K output tokens per request, while Grok 4 Fast 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 has a measured throughput of approximately 90 tokens/second. Throughput data for DeepSeek-V3.1 is not yet available. 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 DeepSeek-V3.1 or Grok 4 Fast 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. DeepSeek-V3.1 costs $0.27/M input and $1.00/M output. Grok 4 Fast costs $0.20/M input and $0.50/M output.
Rank both on the LLM leaderboard, SWE-bench, and Humanity's Last Exam.
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