What Size Needle Is Used For Blood Tests?

28th March 2022

Hypodermic needles are available in different sizes. It is measured according to the gauge of the needle.

You will find needles from gauge size 7G to 33G. As the gauge size increases, the thickness of the needle decreases. While the 7G needle is too thick, the 33G needle is too thin.

Different sizes of needles are used for different purposes. For the blood test, a specific size of the needle is used. If you want to know about the size of the needle used for blood tests, follow this guide. 

Blood Test Needle Size:

The blood test needle is not necessarily an expensive piece of equipment, nor do you have to spend a fortune on it. It is available in every medical store. 

Purchasing the right blood test needle for your procedure can make the difference between success and failure. As there are different sizes of needles available in the market, you need to choose the right size for drawing blood.

You cannot use needles that are very thick as they will hurt the person. You cannot use needles that are too thin as it will take time to draw blood.

The perfect size needle should not be too thick or thin. Needles are available in different gauge sizes. It denotes the length and width of the needle.

For the blood test, needles with gauge size 21G is used—most of the phlebotomist use this size of needle for drawing blood. The width of this needle is 0.8mm. It is not really thick, so there will be minimal pain.

The length of the needle is mostly 25mm and 38mm. It will make the blood drawing procedure much easier. 

Gauges of Needles Used for Blood Test:

Although 21G is the most common needle size for drawing blood, there are other gauges of needles used for blood tests as well. Here are some of the common gauges of needles used for drawing blood.

  • 21 Gauge Needle: As we have discussed above, it is the standard size of the needle used for blood collection. It is a venepuncture needle. The gauge of the needle is small to avoid pain—most of the phlebotomist use this size of needle for a blood test. However, in some cases, the thinner needle is needed for drawing blood. In this size of the needle, the blood flows at a steady rate. It helps to easily collect blood quickly. The thickness of the needle is 0.8mm. 
  • 22 Gauge Needle: It is one size bigger needle that is thinner than 21G size. This size of the needle is used occasionally to collect blood for test purposes. It is slightly smaller than the 21G needle. If the veins in your body are smaller, this size of the needle is used. It is mostly used for kids. The width of the needle is 0.7mm. 
  • 23 Gauge Needle: This is another size of the needle which is used for a blood test. It is also known as a butterfly needle. When the veins are narrow, it is the best option for collecting blood. The colour code is blue. The width of the needle is 0.6mm. It is smaller than 21G and 22G. 

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