The formulations and recipes presented in most materials refer to adult dosages (unless the work is specifically geared toward remedies for children). To work the dosages for children there are several different methods and charts.
Take the age in years of the child and divide by 20 to get the portion of the adult dose to administer.
Example: a 6 year old child = 6 divided by 20 = 3/10ths
Take the age in years of the child and divide by the age in years of the child + 12 and this will equal the portion of the adult dose to administer.
Example: a 6 year old child divided by 6 + 12 (18) = 1/3 the adult dose
Divide the age at the next birthday by 24.
Example: a 5-year-old would be 6 at the next birthday; 6 divided by 24 equals 6/24 or 1/4. Dose would be 1/4 the adult dosage.
Divide the weight in *pounds of the child by 150 to give the approximate fraction of the adult dosage.
(*pounds: using a dosage based on the weight is a more sensible choice. Children vary considerably in size despite their ages. A small 6 year old would require less than a large 6 year old).
When in doubt, always ask a person knowledgeable in the area of herbal dosages.