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Gemini 3.5 Flash

VS
xAI

Grok 4.20

✍️ Analysis by:the whichllmmodel Editorial Team|📅 Updated: June 2026

Decision Recommendation

⚖️ Editorial Verdict: In our analysis, Gemini 3.5 Flash is the premium intelligence choice, scoring 3.3% higher on coding benchmarks. However, this accuracy premium comes with a cost overhead: Grok 4.20 is 1.1x cheaper to run. If you are building high-volume, simple chatbots or processing massive amounts of text where budget is critical, Grok 4.20 offers excellent cost savings. For agentic reasoning, code refactoring, or complex logical tasks, the accuracy premium of Gemini 3.5 Flash fully justifies the cost.

Model Specs

Gemini 3.5 Flash

Benchmarks & Scores

Coding (swe-bench-pro)Winner (+3.3%)
55.1%
Reasoning (gpqa-diamond)Winner (+2.2%)
92.2%

Cost & Performance

Cost (per 1M tokens)
$3.38Input: $1.50 | Output: $9.00
Speed1.2x faster
280 tps
Context Window
1M tokens
Model Specs

Grok 4.20

Benchmarks & Scores

Coding (swe-bench-pro)
51.8%
Reasoning (gpqa-diamond)
90%

Cost & Performance

Cost (per 1M tokens)1.1x cheaper
$3.00Input: $2.00 | Output: $6.00
Speed
233 tps
Context Window
1M tokens
Read our data collection methodology

Frequently Asked Questions

Grok 4.20 is cheaper than Gemini 3.5 Flash. Grok 4.20 has a blended cost of $3.00/1M tokens, which is about 1.1x cheaper than Gemini 3.5 Flash at $3.38/1M tokens.

Gemini 3.5 Flash is faster than Grok 4.20. Gemini 3.5 Flash generates 280 tokens per second (tps) compared to Grok 4.20 which generates 233 tokens per second.

Gemini 3.5 Flash is better for coding tasks. It scores 55.1% on coding evaluations (swe-bench-pro) compared to Grok 4.20 which scores 51.8%.

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