The main difference is how much force and depth you use for the compressions. For a small child, compressions are shallower and often done with one hand instead of two.
Compression depth
For an adult, compress the chest at least 2 inches (about 5–6 cm) deep to be effective.
For a small child, compress about one third the depth of the chest, usually around 2 inches (about 5 cm) at most, because the chest is smaller and more easily compressed.
Hand use and force
On an adult, use two hands on the center of the chest with firm, strong compressions.
On a small child, you may use one hand (or two, depending on size), applying less force to avoid injury while still reaching the correct depth.
What stays the same
For both adults and children, compress at a rate of 100–120 compressions per minute in the center of the chest.
The goal in both cases is full recoil between compressions and minimal interruptions so blood flow is maintained.
