Compare/Gemini 2.5 Flash (Reasoning) vs Grok 4.3

Gemini 2.5 Flash (Reasoning)vsGrok 4.3

Side-by-side comparison of pricing, 12 benchmarks, and generation speed.

Google

Gemini 2.5 Flash (Reasoning)

Input
$0.3/M
Output
$2.5/M
Speed
212 tok/s
TTFT
11.41s
xAI

Grok 4.3

Input
$1.25/M
Output
$2.5/M
Speed
85 tok/s
TTFT
10.70s

Winner by Category

Cheaper
Gemini 2.5 Flash (Reasoning)
Faster (tok/s)
Gemini 2.5 Flash (Reasoning)
Lower Latency
Grok 4.3
Benchmarks (5-7)
Grok 4.3

Pricing Comparison

MetricGemini 2.5 Flash (Reasoning)Grok 4.3
Input ($/M tokens)$0.3$1.25
Output ($/M tokens)$2.5$2.5
Cost for 1M input + 100K output tokens:
Gemini 2.5 Flash (Reasoning)$0.55
Grok 4.3$1.50

Speed Comparison

Output Speed (tokens/s) — higher is better
Gemini 2.5 Flash (Reasoning)
212 tok/s
Grok 4.3
85 tok/s
Time to First Token (seconds) — lower is better
Gemini 2.5 Flash (Reasoning)
11.41s
Grok 4.3
10.70s

Benchmark Comparison

Data from Artificial Analysis API — 12 benchmarks

Intelligence Index
27.053.2
Coding Index
22.241.0
Math Index
73.3
GPQA Diamond
79.0%90.1%
MMLU-Pro
83.2%
LiveCodeBench
69.5%
AIME 2025
73.3%
MATH-500
98.1%
Humanity's Last Exam
11.1%35.0%
SciCode
39.4%47.3%
IFBench
50.3%81.3%
TerminalBench
13.6%37.9%
Gemini 2.5 Flash (Reasoning)5 wins
7 winsGrok 4.3

Frequently Asked Questions

Which is cheaper, Gemini 2.5 Flash (Reasoning) or Grok 4.3?

Gemini 2.5 Flash (Reasoning) is cheaper overall. Its blended price (3:1 input/output ratio) is $0.85/M tokens vs $1.56/M for Grok 4.3.

Which model performs better on benchmarks?

Grok 4.3 wins 7 out of 12 benchmarks compared to 5 for Gemini 2.5 Flash (Reasoning). See the detailed benchmark chart above for per-category results.

Which is faster for real-time applications?

Gemini 2.5 Flash (Reasoning) generates tokens faster at 212 tok/s vs 85 tok/s. However, Grok 4.3 has lower time-to-first-token (10.70s vs 11.41s).

When should I use Gemini 2.5 Flash (Reasoning) vs Grok 4.3?

Choose based on your priorities: Gemini 2.5 Flash (Reasoning) for lower cost, Grok 4.3 for stronger benchmark performance, and Gemini 2.5 Flash (Reasoning) for faster generation. For latency-sensitive apps, check the TTFT comparison above.