DeepSeek-V4.1-Flash vs Grok-4 Fast Reasoning
Comparing DeepSeek-V4.1-Flash and Grok-4 Fast Reasoning across benchmarks, pricing, and capabilities.
DeepSeek · xAI · Updated for 2026
Which is better?
DeepSeek-V4.1-Flash and Grok-4 Fast Reasoning trade strengths across price, capabilities, and technical limits. The better choice depends on the workload.
On price, Grok-4 Fast Reasoning is roughly 1.2x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
Grok-4 Fast Reasoning also accepts a larger context window (2,000,000 input tokens), making it the stronger choice for long documents and large codebases.
Based on current LLM Stats indexes, shared benchmarks, pricing, and model metadata for 2026.
Choose DeepSeek-V4.1-Flash
- you want the most recent training data — it shipped Sep 2026
- you need open weights you can self-host or fine-tune
Choose Grok-4 Fast Reasoning
- cost matters — it's about 1.2x cheaper per token
- you process long inputs — it offers a 2,000,000 token context window
At a glance
The differences that matter most.
Individual benchmarks
20 reported for DeepSeek-V4.1-Flash · 0 for Grok-4 Fast Reasoning
DeepSeek-V4.1-Flash and Grok-4 Fast Reasoningdon't have any common benchmark datasets to compare. They may have been evaluated on different testing suites.
Human preference
Blind head-to-head votes and playground preference scores
Pricing Analysis
Price comparison per million tokens
For input processing, DeepSeek-V4.1-Flash ($0.22/1M tokens) is 1.1x more expensive than Grok-4 Fast Reasoning ($0.20/1M tokens).
For output processing, DeepSeek-V4.1-Flash ($0.66/1M tokens) is 1.3x more expensive than Grok-4 Fast Reasoning ($0.50/1M tokens).
In conclusion, DeepSeek-V4.1-Flash is more expensive than Grok-4 Fast Reasoning.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
Grok-4 Fast Reasoning accepts 2,000,000 input tokens compared to DeepSeek-V4.1-Flash's 1,040,000 tokens. DeepSeek-V4.1-Flash can generate longer responses up to 393,216 tokens, while Grok-4 Fast Reasoning is limited to 30,000 tokens.
Input capabilities
Documented input modalities across available providers
Both DeepSeek-V4.1-Flash and Grok-4 Fast Reasoning support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
DeepSeek-V4.1-Flash
Grok-4 Fast Reasoning
License
Usage and distribution terms
DeepSeek-V4.1-Flash is licensed under MIT, while Grok-4 Fast Reasoning uses a proprietary license.
License differences may affect how you can use these models in commercial or open-source projects.
MIT
Open weights
Proprietary
Closed source
Release Timeline
When each model was launched
DeepSeek-V4.1-Flash was released on 2026-09-10, while Grok-4 Fast Reasoning was released on 2025-08-28.
DeepSeek-V4.1-Flash is 13 months newer than Grok-4 Fast Reasoning.
Sep 10, 2026
1 weeks ago
1.0yr newerAug 28, 2025
1.1 years ago
Knowledge Cutoff
When training data ends
Neither model specifies a knowledge cutoff date.
Unable to compare the recency of their training data.
Provider Availability
DeepSeek-V4.1-Flash is available from Fireworks, DeepInfra, DeepSeek, Novita. Grok-4 Fast Reasoning is available from xAI.
DeepSeek-V4.1-Flash
Grok-4 Fast Reasoning
Outputs Comparison
Judge for yourself.
Run your own prompts against DeepSeek-V4.1-Flash and Grok-4 Fast Reasoning side-by-side, then vote on the output you prefer.
FAQ
Common questions about DeepSeek-V4.1-Flash vs Grok-4 Fast Reasoning.