The diameter of hypodermic needles is expressed as a gauge. The higher the gauge, the smaller the diameter of the needle. To aid in the identification of the needle, manufacturers may color-code the individual needles.
NOTE:
(1) Different manufacturers may use different color coding. The following is used by Becton Dickinson (BD) for its Precision Glide syringe needles.
(2) The diameter associated with each gauge shows some variation.
|
Gauge |
External Diameter in mm (alternate) |
Color (BD) |
|
6 |
5.16, 5.00 |
|
|
7 |
4.57, 4.45 |
|
|
8 |
4.19,4.00 |
|
|
9 |
3.76, 3.68 |
|
|
10 |
3.40, 3.28 |
|
|
11 |
3.05, 3.00 |
|
|
12 |
2.77, 2.67 |
|
|
13 |
2.41, 2.40 |
|
|
14 |
2.11, 2.03 |
|
|
15 |
1.83 |
|
|
16 |
1.65 |
purple |
|
17 |
1.50 |
|
|
18 |
1.27, 1.25 |
pink |
|
19 |
1.07, 1.09 |
|
|
20 |
0.89, 0.90 |
yellow |
|
21 |
0.81, 0.82, 0.80 |
green |
|
22 |
0.71, 0.70 |
black |
|
23 |
0.64, 0.65 |
turquoise |
|
24 |
0.56 |
|
|
25 |
0.51, 0.50 |
blue |
|
26 |
0.46, 0.45 |
tan |
|
27 |
0.41, 0.40 |
gray |
|
28 |
0.36 |
|
|
29 |
0.33, 0.35 |
|
|
30 |
0.30 |
beige (grayish tan) |
|
31 |
0.25 |
|
|
32 |
0.23 |
|
|
33 |
0.20 |
|
|
34 |
0.18 |
|
|
35 |
0.13 |
|
Commonly used needle sizes (from Ayim et al)
|
Gauge |
Diameter in mm |
|
25 |
0.5 |
|
20 |
0.9 |
|
18 |
1.2 |
|
16 |
1.6 |
|
15 |
1.8 |
|
14 |
2.0 |
|
13 |
2.3 |
|
12 |
2.6 |
|
11 |
3.0 |
If this data is evaluated in Minitab:
diameter of needle in mm =
= (0.01111 * ((gauge number)^2)) - (0.5733 * (gauge number)) + 7.904
