Urns are sized according to volume, in cubic inches.
A simple rule to guide you is 1 pound = 1 cubic inch. For example, for 8 pounds you would need at least 8 cubic inches.
It is always good to have more space in the urn than you need. Remember too that if a baby or child is cremated in a casket, you will receive back more ashes. For the smallest of infants you need to add on at least 5 cubic inches to account for the casket.
Using the example above, 8 pounds plus 5 cubic inches extra to account for the casket would require an urn of at least 13 cubic inches. Our Baby Urn (which is 22 cubic inches) would have plenty of room for the ashes.
By choosing a larger size urn, you will have sufficient room for tiny mementos such as a hospital bracelet for preemies and/or booties. With our Baby Urn and Infant Urn we provide for free a small white flannel bag for this purpose. See Purchasing Guidelines.