Grok 3 Fast
Pricing & Specs
xAI · $5 input / $25 output per 1M tokens · 131.072K context window
No longer offered on OpenMark
Grok 3 Fast is no longer offered on OpenMark (deprecated or superseded upstream). Its specs are kept here for reference — if you're still running it in production, it's worth benchmarking current alternatives: newer models are often cheaper AND better on the same task.
Grok 3 Fast API Pricing
| Tokens | Price |
|---|---|
| Input | $5 / 1M tokens |
| Output | $25 / 1M tokens |
| Cached input | $1.25 / 1M tokens |
Cached tokens pricing is available for this model.
What that means in practice
Grok 3 Fast Specs
| Spec | Value |
|---|---|
| Context window | 131.072K tokens |
| Input modalities | text |
| Output modalities | text |
| Latency (measured by OpenMark) | ~544ms median response |
| Reasoning model | No |
| Tool / function calling | Yes |
| JSON mode | Yes |
| Streaming | Yes |
| Prompt caching | Yes |
Capabilities
Notes
Removed from xAI docs Jan 2026. Use grok-4-fast-reasoning instead.
FAQ
How much does Grok 3 Fast cost?
Grok 3 Fast costs $5 per 1M input tokens and $25 per 1M output tokens ($1.25 per 1M cached input tokens).
What is Grok 3 Fast's context window?
Grok 3 Fast has a 131.072K-token context window.
Can I test Grok 3 Fast on my own task?
Grok 3 Fast is no longer offered on OpenMark, but you can benchmark its current alternatives from xAI and other providers on your own task — free tier available.
Still using Grok 3 Fast?
It's been superseded. Benchmark its current alternatives on your actual
workload — you'll likely find something cheaper AND better. Free tier available.