Needle sizes: what do 23G, 27G and 30G mean?
Needles are often labelled with both needle gauge (G) and length in millimetres. These two specifications describe different things and should be read together. ISO 9626 covers needle tubing for medical device manufacturing and uses both metric size designations and G designations.
What does G mean on a needle?
The G number is a size designation for the needle diameter. A higher G number generally means a smaller outside diameter. This means that 30G is thinner than 27G, which in turn is thinner than 23G. However, the G number does not indicate how long the needle is.
What does the measurement after × mean?
In a designation such as 27G × 19 mm, 27G indicates the needle gauge and 19 mm the needle length. It is therefore important not to compare only the G number.
Tilden's current Terumo Agani range includes:
The variants are also available in larger packs. See the full Needles category.
Colour coding is not the same as intended use
ISO 6009 describes colour coding for identifying the size of certain single-use needles. Colour is therefore an identification aid but does not replace the printed G number, length or the product's instructions for use. The standard does not apply to pen needles.
Do not choose a needle based on gauge alone
Which needle is appropriate depends on the intended use and the product instructions. This guide only explains how to read the dimensions and is not a recommendation of which size to use for a particular injection or treatment.
If you use a separate needle with a syringe, the connection type should also be checked. Read What is Luer Lock? and see Tilden's Luer Lock syringes.
This is general product information and does not replace instructions for use, a prescription or advice from healthcare professionals.