Finger tip unit

In medicine, a finger tip unit (FTU) is defined as the amount of ointment, cream or other semi-solid dosage form expressed from a tube with a 5 mm diameter nozzle, applied from the distal skin-crease to the tip of the index finger of an adult. The "distal skin-crease" is the skin crease over the joint nearest the end of the finger. One FTU is enough to treat an area of skin twice the size of the flat of an adult's hand with the fingers together, i.e. a "handprint". Two FTUs are approximately equivalent to 1 g of topical steroid.

One handprint is 0.8% (i.e. approximately 1%) of the total body surface area, and one FTU covers approximately two handprints. As two FTUs are approximately equivalent to 1g of topical application, the "Rule of Hand" states that "4 hand areas = 2 FTU = 1 g".

In the original study in the UK, one FTU weighed 0.49 g in men and 0.43 g in women. The area covered by one FTU was 312 cm² in men and 257 cm² in women. Very similar results were found in a Mexico study. The weight of an FTU has been recalculated in Japan, relating to the use of 5 g tubes of ointment with a much smaller nozzle diameter. The weight of ointment is less if the nozzle diameter is smaller than the standard 5 mm.

When a topical drug was used as a foam, the weight of an FTU was 52.5 μg: the area covered by one foam FTU was less than that of an FTU of cream.