Verdict
Built from the measurements below
- Accuracy is too close to call: Gemini 3.8 Flash scored 82.5% and Grok 4.7 80.0% on the same 80 questions, a gap within what chance alone could produce.
- Gemini 3.8 Flash is 6.8× cheaper per question as billed ($0.0037 vs $0.025), reasoning tokens included.
- Gemini 3.8 Flash generates text 1.8× faster: 142 tokens per second against 77.
- Grok 4.7 starts answering sooner: 1.9 s to the first token, against 3.2 s for Gemini 3.8 Flash.
- Gemini 3.8 Flash accepts more context: 1M tokens against 500k.
Which should you choose?
Choose Gemini 3.8 Flash for the lower cost per correct answer ($0.0045 against $0.031), faster streaming, shorter outputs (about 925 tokens per question against 3,952) and a 1M-token context window. Choose Grok 4.7 for a quicker first token. The widest subject gap is in law: Gemini 3.8 Flash answered 6 of 6 correctly, Grok 4.7 4 of 6. With so few questions per subject, treat this as a lead to test on your own prompts, not a result.
Accuracy gap +2.5 points (z = 0.41). We call a winner only when z is at least 1.96, the usual 95% threshold. Speed, latency and price need a 10% margin.