In most cases the waveguide size will be known - but in an unknown system, the best way to determine the waveguide size is to unbolt a section and measure the internal bore. If this is not possible, the outside of the waveguide can be measured and the size determined from the chart below.

This isn’t always foolproof as there are thin wall waveguides (sometimes used in aerospace applications) and thick wall waveguides (sometimes used in highly pressurised waveguides).

Some applications use ¼ or ½ height waveguides, which may not be exactly ¼ or ½ height.

Waveguide designationsFrequency range (GHz)internal dimensionsexternal dimensions
RCSC53-IECIEA WR()inchesmm (approx)inchesmm (approx)
WG00R323000.32 - 0.4923.0 x 11.5584.2 x 292.1  
WG0R421000.35 - 0.5321.0 x 10.5533.4 x 266.7  
WG1R518000.41 - 0.6218.0 x 9.0457.2 x 228.6  
WG2R615000.49 - 0.7515.0 x 7.5381 x 190.5  
WG3R811500.64 - 0.9811.5 x 5.75292.1 x 146.05  
WG4R99750.76 - 1.159.75 x 4.875247.65 x 123.825  
WG5R127700.96 - 1.467.7 x 3.85195.58 x 97.79  
WG6R146501.14 - 1.736.5 x 3.25165.1 x 82.556.66 x 3.410169.16 x 86.61
WG7R185101.45 - 2.205.1 x 2.55129.54 x 64.775.26 x 2.71133.60 x 68.83
WG8R224301.72 - 2.614.3 x 2.15109.22 x 54.614.46 x 2.31113 x 58.67
WG9AR263402.17 - 3.303.4 x 1.786.36 x 43.183.56 x 1.8690.42 x 47.24
WG10R322842.60 - 3.952.84 x 1.3472.136 x 34.0363.00 x 1.5076.2 x 38.1
WG11AR402293.22 - 4.902.29 x 1.14558.166 x 29.0832.418 x 1.23761.42 x 32.33
WG12R481873.94 - 5.991.872 x 0.87247.549 x 22.1492.000 x 1.00050.80 x 25.40
WG13R581594.64 - 7.051.59 x 0.79540.386 x 20.1931.718 x 0.92343.64 x 23.44
WG14R701375.38 - 8.181.372 x 0.62234.849 x 15.7991.500 x 0.75038.10 x 19.05
WG15R841126.58 - 10.01.122 x 0.49728.499 x 12.6241.250 x 0.62531.75 x 15.88
WG16R100908.20 - 12.50.9 x 0.422.86 x 10.161.000 x 0.50025.40 x 12.70
WG17R120759.84 - 15.00.75 x 0.37519.05 x 9.5250.850 x 0.47521.59 x 12.06
WG18R1406211.9 - 18.00.622 x 0.31115.799 x 7.8990.702 x 0.39117.83 x 9.93
WG19R1805114.5 - 22.00.510 x 0.25512.954 x 6.4770.590 x 0.35514.99 x 8.51
WG20R2204217.6 - 26.70.420 x 0.17010.668 x 4.3180.500 x 0.25012.70 x 6.35
WG21R2603421.7 - 33.00.340 x 0.1708.636 x 4.3180.420 x 0.25010.67 x 6.35
WG22R3202826.4 - 40.10.280 x 0.1407.112 x 3.5560.360 x 0.2209.14 x 5.59
WG23R4002233.0 - 50.10.224 x 0.1125.690 x 2.8450.304 x 0.1927.72 x 4.88
WG24R5001939.3 - 59.70.188 x 0.0944.775 x 2.3880.268 x 0.1746.81 x 4.42
WG25R6201549.9 - 75.80.148 x 0.0743.759 x 1.8800.228 x 0.1545.79 x 3.91

Double Ridge