Context Window

Compare

Grok 4 1 Fast Reasoning Latest vs Phi 4

This page is context-first: how much text each model can take in one request. Full specs adds capabilities and limits; the pricing matrix below is only about $/million tokens from hosts that list both models.

Xai

Model

Grok 4 1 Fast Reasoning Latest

Image inputTool calling

Context window

2M

2,000,000 tokens · ~1.5M words

Model page
Microsoft

Model

Phi 4

Tool calling

Context window

16K

16,384 tokens · ~12K words

Model page

Context window · side by side

Bar length is relative to the larger of the two windows (100% = max of this pair). This is not pricing.

Grok 4 1 Fast Reasoning Latest2M
Phi 416K

Grok 4 1 Fast Reasoning Latest has about 122.1× the context window of the other in this pair.

Token calculator →Memory savings →

Grok 4 1 Fast Reasoning Latest has 12107% more context capacity (2000K vs 16K tokens). Phi 4 is 65% cheaper on input.

Quick verdicts

Short takeaways — validate with your own workloads.

  • Long document processing

    Use Grok 4 1 Fast Reasoning Latest. Its 2000K context fits entire documents without chunking (vs 16K).

  • RAG / high-volume retrieval

    Use Phi 4. Input tokens are 65% cheaper — critical when sending large retrieved contexts.

  • Long output (reports, code files)

    Use Grok 4 1 Fast Reasoning Latest. Its 2000K max output lets you generate complete artifacts in one request.

Full specs

Context, output, capabilities, and dates. Green highlights the favorable value where we compute a winner.

SpecGrok 4 1 Fast Reasoning LatestPhi 4
Context window2,000,000 tokens (2000K)16,384 tokens (16K)
Max output tokens2,000,000 tokens (2000K)16,384 tokens (16K)
Speed tierDeepBalanced
VisionYesNo
Function callingYesYes
Extended thinkingYesNo
Prompt cachingYesNo
Batch APINoNo
Release dateN/AJan 2025

Pricing matrix

Dollar rates only: hosts that list both models, per 1M tokens. For how much text fits, use the context section above — not this table.

ProviderGrok 4 1 Fast Reasoning Latest inGrok 4 1 Fast Reasoning Latest outPhi 4 inPhi 4 out
Azure——$0.125/M$0.500/M
Deepinfra——$0.070/M$0.140/M
Xai$0.200/M$0.500/M——

Frequently asked questions

Grok 4 1 Fast Reasoning Latest has a larger context window: 2000K tokens vs 16K. For long documents, large codebases, or extended agent sessions, the larger context window reduces the need to chunk inputs or summarize history.

Powered by Mem0

Use a smaller model.
Get better results.

Mem0 gives your AI long-term memory so you stop re-sending context on every call. That means you can use a smaller, faster, cheaper model — and still get better answers.

Calculate your savingsLearn about Mem0

Example: a multi-turn chat session

Without Mem0~128K tokens sent
Full history
Repeated info
Old context
With Mem0~20K tokens sent
Key memories
Current turn

80% less to send — works with any model