Grok 4 Fast vs o3
Side-by-side benchmark comparison across coding, math, reasoning, speed, and pricing.
o3 by OpenAI wins on 9 of 14 benchmarks against Grok 4 Fast by xAI, which leads on 5. This head-to-head comparison covers coding, math, reasoning, speed, and pricing metrics from our benchmark data.
Category-by-Category Breakdown
General Intelligence: In general intelligence, o3 scores 1380 on Chatbot Arena ELO compared to Grok 4 Fast's 1370, while o3 scores 84.0% on MMLU-Pro compared to Grok 4 Fast's 80.0%.
Coding: In coding, o3 scores 90.0% on HumanEval+ compared to Grok 4 Fast's 85.0%, while o3 scores 69.1% on SWE-bench Verified compared to Grok 4 Fast's 48.0%, while o3 scores 70.0% on LiveCodeBench compared to Grok 4 Fast's 52.0%.
Math: In math, o3 scores 96.0% on MATH compared to Grok 4 Fast's 84.0%, while o3 scores 98.5% on GSM8K compared to Grok 4 Fast's 94.0%.
Reasoning: In reasoning, o3 scores 83.3% on GPQA Diamond compared to Grok 4 Fast's 60.0%, while o3 scores 75.7% on ARC-AGI compared to Grok 4 Fast's 38.0%.
Context: In context, Grok 4 Fast scores 256K on Context Length compared to o3's 200K.
Pricing Comparison
Grok 4 Fast costs $0.20/1M input tokens and $0.50/1M output tokens, while o3 costs $2.0/1M input and $8.0/1M output. Grok 4 Fast is the more affordable option for API usage.
Speed Comparison
Grok 4 Fast generates output at 110 tok/s compared to o3's 40 tok/s, and the time to first token is 220 ms for Grok 4 Fast versus 800 ms for o3. Grok 4 Fast delivers faster throughput.
Verdict
For developers prioritizing affordability and speed, Grok 4 Fast has the edge. For those who value coding and general intelligence and math, o3 is the stronger choice.
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Grok 4 Fast vs o3 — FAQ
Which is better, Grok 4 Fast or o3?
o3 wins on more benchmarks overall (9 vs 5). However, the best choice depends on your specific needs — each model excels in different areas.
How does Grok 4 Fast compare to o3 for coding?
o3 is better for coding, scoring 69.1% on SWE-bench Verified compared to 48.0%. SWE-bench tests real-world software engineering by resolving actual GitHub issues.
Is Grok 4 Fast cheaper than o3?
Yes, Grok 4 Fast is cheaper. Grok 4 Fast costs $0.20/1M input and $0.50/1M output tokens. o3 costs $2.0/1M input and $8.0/1M output tokens.
Which is faster, Grok 4 Fast or o3?
Grok 4 Fast is faster, generating output at 110 tok/s compared to 40 tok/s. Faster output speed means shorter wait times for API responses.
What benchmarks does the Grok 4 Fast vs o3 comparison cover?
This comparison covers 14 benchmarks including Chatbot Arena ELO, MMLU-Pro, HumanEval+, MATH, GPQA Diamond, SWE-bench Verified, Output Speed, LiveCodeBench, and more. Metrics span general intelligence, coding, math, reasoning, speed, and cost categories.