xAI Grok 3.5 (256k) vs DeepSeek V4 (128k)
Side-by-side comparison of pricing, context window, capabilities, and a real-cost sample workload.
Option A
xAI Grok 3.5 (256k)
by xAI
Context: 256K
Input: $5.00 / 1M
Output: $25.00 / 1M
Released: 2026-03
Option B
DeepSeek V4 (128k)
by DeepSeek
Context: 128K
Input: $0.50 / 1M
Output: $2.00 / 1M
Released: 2026-02
Detailed Comparison
| Dimension | xAI Grok 3.5 (256k) | DeepSeek V4 (128k) |
|---|---|---|
| Provider | xAI | DeepSeek |
| Context window Winner | 256K | 128K |
| Input price ($/1M) Winner | $5.00 | $0.50 |
| Output price ($/1M) Winner | $25.00 | $2.00 |
| Sample workload cost Winner 1M input + 500K output tokens
|
$17.50 | $1.50 |
| Released Winner | 2026-03 | 2026-02 |
| Tokenizer | grok | deepseek |
The verdict
On the dimensions we measured, DeepSeek V4 (128k) wins more often — particularly on cost-effectiveness for a typical 1M+0.5M workload.
xAI Grok 3.5 (256k) — Key features
xAI's latest flagship model with expanded context, improved reasoning, and deeper integration with real-time data from X platform.
- 256K token context window
- Advanced reasoning and coding
- Real-time information access
- Trained on expanded Colossus cluster
- Improved multimodal capabilities
DeepSeek V4 (128k) — Key features
DeepSeek's fourth-generation open-weights model with state-of-the-art reasoning at remarkably low cost. Strong performance on coding and math benchmarks.
- 128K token context window
- Open-weights model
- Exceptional cost efficiency
- Strong coding and math
- Mixture-of-experts architecture
How to choose
- Pick the cheaper model if your workload is mostly straightforward classification, extraction, or summarization.
- Pick the bigger context if you process long documents, large codebases, or multi-document research.
- Pick the more recent release if you need state-of-the-art reasoning quality and don't mind paying a bit more.
- Use both via a routing layer — send simple tasks to the cheaper one and complex tasks to the smarter one. This is the highest-ROI optimization in production AI.
Estimate the real cost of either model for your prompts using our Token Calculator.