Verdict
Built from the measurements below
- Accuracy is too close to call: Granite 4.2 8B scored 36.2% and Phi 4 41.2% on the same 80 questions, a gap within what chance alone could produce.
- Granite 4.2 8B is 1.6× cheaper per question as billed ($0.000077 vs $0.00012), reasoning tokens included.
- Phi 4 generates text 1.7× faster: 103 tokens per second against 60.
- Phi 4 starts answering sooner: 0.5 s to the first token, against 0.6 s for Granite 4.2 8B.
- Granite 4.2 8B accepts more context: 131k tokens against 16k.
Which should you choose?
Choose Granite 4.2 8B for the lower cost per correct answer ($0.00021 against $0.00029), shorter outputs (about 227 tokens per question against 699) and a 131k-token context window. Choose Phi 4 for faster streaming and a quicker first token. The widest subject gap is in medicine: Phi 4 answered 4 of 11 correctly, Granite 4.2 8B 1 of 11. With so few questions per subject, treat this as a lead to test on your own prompts, not a result.
Accuracy gap -5.0 points (z = -0.65). We call a winner only when z is at least 1.96, the usual 95% threshold. Speed, latency and price need a 10% margin.