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grok-4-fast-reasoning vs claude-sonnet-4-5-20250929

Pricing, Performance & Features Comparison

Price unit:

grok-4-fast-reasoning

Authorxai

Context Length2M

Reasoning

Providers1

ReleasedSep 2025

Knowledge Cutoff-

License-

xAI latest advancement in cost-efficient reasoning models.

Input$0.2

Output$0.5

Latency (p50)2.3s

Output Limit-

Function Calling

JSON Mode

-

Input-

Output-

in$0.2out$0.5-write$0.05

Latency (24h)

Success Rate (24h)

claude-sonnet-4-5-20250929

Authoranthropic

Context Length200K

Reasoning

-

Providers1

ReleasedSep 2025

Knowledge Cutoff-

License-

Our best model for complex agents and coding, with the highest intelligence across most tasks.

Input$3

Output$15

Latency (p50)2.4s

Output Limit64K

Function Calling

JSON Mode

-

Input-

Output-

in$3out$15cache$0.3write$3.8

Latency (24h)

Success Rate (24h)