Claude Sonnet 5.5 vs Grok 4.20 0309 Reasoning

Price, context window & benchmark comparison

Anthropic

Claude Sonnet 5.5

Anthropic
$2.00 / $10.00
Input / Output · per 1M tokens
VS
xAI

Grok 4.20 0309 Reasoning

xAI
$1.25 / $2.50
Input / Output · per 1M tokens
Compare different models
Anthropic
xAI
Verdict: Grok 4.20 0309 Reasoning is 2.6× cheaper than Claude Sonnet 5.5 on a typical 3:1 input/output mix.
Claude Sonnet 5.5Grok 4.20 0309 Reasoning
Input price / 1M$2.00$1.25
Output price / 1M$10.00$2.50
Blended price (3:1)$4.00$1.56
Cached input / 1M$0.10$0.20
Context window1M1M
Max output128K30K
Intelligence index54.2—
Coding index——
Providers10—
Best provider uptime (30m)100.0%—
Vision inputYesYes
ReasoningYesYes
Tool callingYesYes
Released2026-09-282026-10-16
Retirement——

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FAQ

Which is cheaper, Claude Sonnet 5.5 or Grok 4.20 0309 Reasoning?

Grok 4.20 0309 Reasoning is 2.6× cheaper than Claude Sonnet 5.5 on a typical 3:1 input/output mix.

Claude Sonnet 5.5 vs Grok 4.20 0309 Reasoning: which has a bigger context window?

Claude Sonnet 5.5: 1,000,000 tokens. Grok 4.20 0309 Reasoning: 1,000,000 tokens.

How much would 1 million requests cost?

At 2,000 input + 500 output tokens per request: Claude Sonnet 5.5 ≈ $9,000, Grok 4.20 0309 Reasoning ≈ $3,750.

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