https://www.stlouischildrens.org/health-resources/dosage-tables

Weight	Infant Drops 160 mg / 5 ml	Children's Liquid (160 mg / 5 ml )	Chewables (80 mg)	Jr. Chewables (160 mg )
6-11 Lbs.	1.25 ml
12 - 17 lbs.	2.5 ml	1/2 tsp. = 2.5 ml
18 - 22 lbs.	3.75 ml	3/4 tsp. = 3.75 ml
22 -33 lbs.	5 ml	1 tsp = 5.0 ml	2
34 - 44 lbs.		1 1/2 tsp. = 7.5 ml	3
45 - 55 lbs.		2 tsp. = 10 ml	4	2
56 - 66 lbs.		2 1/2 tsp. = 12.5 ml	5	2 1/2
66 - 77 lbs.		3 tsp. = 17.5 ml	6	3
88 lbs. +				4

Advil Dosing

Weight	Infant Drops (50mg / 1.25 ml)	Children's Liquid (100mg / 5 ml	Chewables ( 50 mg )	Jr. chewables (100 mg )
12 - 17 lbs.	1.25 ml
18 - 22 lbs.	1.875 ml
22 - 33 lbs.		1 tsp = 5.0 ml	2
34 - 44 lbs.		1 1/2 tsp. = 7.5 ml	3
45 - 55 lbs.		2 tsp. = 10 ml	4	2
56 - 66 lbs.		2 1/2 tsp. = 12.5 ml	5	2 1/2
67 - 88 lbs.		3 1/2 tsp. 15 ml	6	3

We strongly advise that parents do not administer aspirin to children less than 16 years of age, especially during viral illnesses, due to the possibility of Reye syndrome. We do not routinely recommend the practice of rotating doses of Tylenol and Ibuprofen when a child has a fever.