Most people apply too little sunscreen. This results in sunscreen users achieving an SPF (Sun Protection Factor) significantly less than is specified on the product label (between 50-80% less).
Apply sunscreen liberally – for the average size adult this means at least a teaspoon for each limb, front and back of the body and approx half a teaspoon for the face, neck and ears.
This equates to approximately 35ml per application for an adult (7 teaspoonfuls = approx 35ml).
For an average toddler this equates to approximately 18ml for a full body application (say 1/2 a teaspoon of sunscreen to each limb, face (neck and ears) etc.
There is no evidence that sunscreen used on small areas of a baby's skin has any harmful effects. No sunscreen provides 100% protection. Babies need to be physically well protected from UVR by clothing, hats and shade. You only need to use sunscreen on very small areas of baby's exposed skin eg, legs, arms and feet etc when direct UV expoure is unavoidable.