Syringe Needle Gauge Table

Find below the complete table of the inner and outer diameters of hypodermic needle gauges. In microfluidics, needles are mostly used to connect a syringe to a soft-walled tubing. You can use it to determine the needle you should use depending on the inner diameter of your soft-walled tubing.

Example: 23G needle = 0.02525″ or 0.6414 mm (outer diameter) – 0.01325″ or 0.337 mm (inner diameter).

Needle gauge	Outer diameter (inches)	Outer diameter (mm)	Inner diameter (inches)	Inner diameter (mm)
7	0.180	4.572	0.150	3.810
8	0.165	4.191	0.135	3.429
9	0.148	3.759	0.118	2.997
10	0.134	3.404	0.106	2.692
11	0.120	3.048	0.094	2.388
12	0.109	2.769	0.085	2.159
13	0.095	2.413	0.071	1.803
14	0.083	2.108	0.063	1.600
15	0.072	1.829	0.054	1.372
16	0.065	1.651	0.047	1.194
17	0.058	1.473	0.042	1.067
18	0.050	1.270	0.033	0.838
19	0.042	1.067	0.027	0.686
20	0.03575	0.9081	0.02375	0.603
21	0.03225	0.8192	0.02025	0.514
22	0.02825	0.7176	0.01625	0.413
22s	0.02825	0.7176	0.006	0.152
23	0.02525	0.6414	0.01325	0.337
24	0.02225	0.5652	0.01225	0.311
25	0.02025	0.5144	0.01025	0.260
26	0.01825	0.4636	0.01025	0.260
26s	0.01865	0.4737	0.005	0.127
27	0.01625	0.4128	0.00825	0.210
28	0.01425	0.3620	0.00725	0.184
29	0.01325	0.3366	0.00725	0.184
30	0.01225	0.3112	0.00625	0.159
31	0.01025	0.2604	0.00525	0.133
32	0.00925	0.2350	0.00425	0.108
33	0.00825	0.2096	0.00425	0.108
34	0.00725	0.1842	0.00325	0.0826

table: Needle gauge size

💡Tip: always use a needle with a larger outer diameter than the inner diameter of your tubing!

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