When reading a needle gauge chart, a higher needle gauge is associated with a thinner the needle size, according to Becton Dickinson Diagnostics. Needle size get smaller as you move down the chart.
A needle gauge chart gives the measurement of the outer diameter, inner diameter and wall thickness for a needle at a particular gauge, indicates the Journal of Diabetes, Science and Technology. The appropriate gauge needed is determined by the needle measurements and the details of the medication being given, adds NursingLink. These factors include the type and viscosity of the medication, the desired absorption rate for the medication, the size and age of the individual receiving the injection, and the individual’s mobility status.
Large gauge needles are used to deliver rapidly absorbed medications, notes NursingLink. In adults, medications are typically given with 21 to 23 gauge needles. Large gauge needles are also used for younger individuals and for injections into delicate and sensitive areas, adds the Journal of Diabetes, Science and Technology. Injections given to children commonly use a thinner 25 to 27 gauge needle. Injections that deliver diabetic medications and vaccinations use ultra-fine needles with a 30 or 31 gauge.
Smaller gauge needles have larger inner and outer diameters, suggests the Journal of Diabetes, Science and Technology. These are used for quick delivery of large quantities of drugs and fluids, including donated blood. They are also used to collect tissue biopsies, adds Acta Radiologica.