Would a 7-1/4 inch circular saw be able to cut 4x4s?

My dad said that he's always wanted a 8" circular saw so he could cut 4x4s but the only 8" one I found is specifically for metal cutting. Is a 7-1/4 inch circular saw an 8" "nominal" saw? Or should I just give him money for his birthday so he can get the one he wants?
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