DeepSeek: DeepSeek V3.1 Terminus vs xAI: Grok 4.1 Fast
Head-to-head API pricing and cost comparison between DeepSeek’s DeepSeek: DeepSeek V3.1 Terminus and xAI’s xAI: Grok 4.1 Fast. Prices auto-refresh daily from OpenRouter.
xAI: Grok 4.1 Fast is 5% cheaper for input tokens; xAI: Grok 4.1 Fast also wins on output tokens.
Side-by-side comparison
| Spec | DeepSeek: DeepSeek V3.1 Terminus | xAI: Grok 4.1 Fast |
|---|---|---|
| Input price (per 1M) | $0.21 | $0.20 |
| Cached input (per 1M) | $0.13 | $0.05 |
| Output price (per 1M) | $0.79 | $0.50 |
| Batch input (per 1M) | — | — |
| Batch output (per 1M) | — | — |
| Reasoning price (per 1M) | — | — |
| Context window | 164K | 2000K |
| Vision support | No | Yes |
| Caching support | Yes | Yes |
| Batch API | No | No |
| Reasoning capability | No | No |
Monthly cost at volume
Estimated monthly API spend at common production traffic levels (input/output tokens per request shown).
| Volume | DeepSeek: DeepSeek V3.1 Terminus | xAI: Grok 4.1 Fast | Savings |
|---|---|---|---|
1K req/day 500in / 200out tokens | $7.89 | $6.00 | $1.89 xAI: Grok 4.1 Fast wins |
10K req/day 1500in / 500out tokens | $213.00 | $165.00 | $48.00 xAI: Grok 4.1 Fast wins |
100K req/day 3000in / 800out tokens | $3,786 | $3,000 | $786.00 xAI: Grok 4.1 Fast wins |
1M req/day 8000in / 2000out tokens | $97,800 | $78,000 | $19,800 xAI: Grok 4.1 Fast wins |
Adjust input/output token counts, request volume, batch & cached pricing.
Related comparisons
- Anthropic: Claude Haiku 4.5 vs DeepSeek: DeepSeek V3.1 TerminusCompare pricing →
- Anthropic: Claude Opus 4.7 vs DeepSeek: DeepSeek V3.1 TerminusCompare pricing →
- Anthropic: Claude Sonnet 4.6 vs DeepSeek: DeepSeek V3.1 TerminusCompare pricing →
- Cohere: Command R (08-2024) vs DeepSeek: DeepSeek V3.1 TerminusCompare pricing →
Frequently asked questions
Which is cheaper, DeepSeek: DeepSeek V3.1 Terminus or xAI: Grok 4.1 Fast?
For input tokens, xAI: Grok 4.1 Fast is roughly 5% cheaper at $0.20/1M vs $0.21/1M. For output tokens, xAI: Grok 4.1 Fast wins at $0.50/1M. Real-world cost depends on your input/output ratio — use the calculator to model your actual workload.
What’s the context window difference?
DeepSeek: DeepSeek V3.1 Terminus has a context window of 164K tokens. xAI: Grok 4.1 Fast offers 2000K tokens. Larger context windows are valuable for long documents, RAG pipelines, and multi-turn conversations — but they come with higher input-token bills if you fill them every request.
Should I use DeepSeek: DeepSeek V3.1 Terminus or xAI: Grok 4.1 Fast?
Choose DeepSeek: DeepSeek V3.1 Terminus if you’re already on the DeepSeek stack, want broad ecosystem support, or prefer its feature set. Choose xAI: Grok 4.1 Fast for xAI’s ecosystem, native vision input, or its cheaper input tokens. Run a small benchmark on your own prompts before committing — price is only one axis.
How are these prices kept current?
Prices are pulled directly from OpenRouter’s public models API once every 24 hours via a Convex cron job, then normalized to per-1M-token figures. Last refresh: Apr 21, 2026.