The most common mistake when measuring bearings is to measure metric bearings in inches and imperial bearings in mm.
Metric bearings will have dimensions, such as 20mm inner diameter x 47mm outside diameter x 14mm width/depth = 6204 series metric bearing.
Imperial bearings will have dimensions, such as 12.7mm inner diameter x 28.57mm outside diameter x 7.87mm width/depth in fractions that is 1/2 inch x 1-1/8 inch x 5/16 inch = KLNJ1/2 series imperial bearing.
From the above, you can see you need to measure the inner diameter (d), the outer diameter (D) and the width/depth (B) of the bearing to identify it. See the below image for reference:
Many unit converters are available to go from metric to imperial and vice versa, just search in Google for “metric imperial converter” and you should find something to help. We can of course measure your bearings for you. Please ensure your items are clean and post them to us stating how many of each you require and in what brand.