Answers by TheMediTary.Com - Last updated: 14-Jul-2023
This is the dosing information for amoxicillin which would apply to a sinus infection:
Adults, teenagers, and children weighing more than 40 kilograms (kg) (88 pounds) —250 milligrams (mg) to 500 mg every eight hours or 500 mg to 875 mg every twelve hours, depending on the type and severity of the infection.
Your own Doctor will have an accurate knowledge on your condition and other relevant medical factors so it is important to follow dose instructions from your Doctor.
https://www.drugs.com/cons/amoxil.html