DeepSeek-V2.5 vs Grok-4 Fast Reasoning
Comparing DeepSeek-V2.5 and Grok-4 Fast Reasoning across benchmarks, pricing, and capabilities.
DeepSeek · xAI · Updated for 2026
Which is better?
DeepSeek-V2.5 and Grok-4 Fast Reasoning trade strengths across price, capabilities, and technical limits. The better choice depends on the workload.
On price, DeepSeek-V2.5 is roughly 1.6x 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-V2.5
- cost matters — it's about 1.6x cheaper per token
- you need open weights you can self-host or fine-tune
Choose Grok-4 Fast Reasoning
- you process long inputs — it offers a 2,000,000 token context window
- you want the most recent training data — it shipped Aug 2025
At a glance
The differences that matter most.
Individual benchmarks
15 reported for DeepSeek-V2.5 · 0 for Grok-4 Fast Reasoning
DeepSeek-V2.5 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-V2.5 ($0.14/1M tokens) is 1.4x cheaper than Grok-4 Fast Reasoning ($0.20/1M tokens).
For output processing, DeepSeek-V2.5 ($0.28/1M tokens) is 1.8x cheaper than Grok-4 Fast Reasoning ($0.50/1M tokens).
In conclusion, Grok-4 Fast Reasoning is more expensive than DeepSeek-V2.5.*
* 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-V2.5's 8,192 tokens. Grok-4 Fast Reasoning can generate longer responses up to 30,000 tokens, while DeepSeek-V2.5 is limited to 8,192 tokens.
Input capabilities
Documented input modalities across available providers
Grok-4 Fast Reasoning supports multimodal inputs, whereas DeepSeek-V2.5 does not.
Grok-4 Fast Reasoning can handle both text and other forms of data like images, making it suitable for multimodal applications.
DeepSeek-V2.5
Grok-4 Fast Reasoning
License
Usage and distribution terms
DeepSeek-V2.5 is licensed under deepseek, 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.
deepseek
Open weights
Proprietary
Closed source
Release Timeline
When each model was launched
DeepSeek-V2.5 was released on 2024-05-08, while Grok-4 Fast Reasoning was released on 2025-08-28.
Grok-4 Fast Reasoning is 16 months newer than DeepSeek-V2.5.
May 8, 2024
2.4 years ago
Aug 28, 2025
1.1 years ago
1.3yr newerKnowledge Cutoff
When training data ends
Neither model specifies a knowledge cutoff date.
Unable to compare the recency of their training data.
Provider Availability
DeepSeek-V2.5 is available from DeepSeek, DeepInfra, Hyperbolic. Grok-4 Fast Reasoning is available from xAI.
DeepSeek-V2.5
Grok-4 Fast Reasoning
Outputs Comparison
Judge for yourself.
Run your own prompts against DeepSeek-V2.5 and Grok-4 Fast Reasoning side-by-side, then vote on the output you prefer.
FAQ
Common questions about DeepSeek-V2.5 vs Grok-4 Fast Reasoning.