Gauge Fit Guide

GAUGE FIT CHART
A	B	C	D	E	Price
Our electronic caliper  (ECM) measurement	Our ECM in hundredths of an inch	Nearest  (NE) equivalent in inch fractions	NE in hundredths of an inch	Difference between ECM and NE in mm
10mm	.34	3/8	.38”	.04”	$10.95
12mm	.47”	1/2	.50”	.03”	$12.95
14mm	.55”	9/16	.56”	.01”	$15.95
16mm	.63”	5/8	.63”	.00”	$17.95
18mm	.71”	11/16	.69”	.02”	$19.95
20mm	.79”	13/16	.81”	.02”	$21.95
22mm	.87”	7/8	.86”	.01	$23.95
24mm	.95”	15/16	.94”	.01”	$25.95

Relevant abbreviations and calculations

Mm = millimeters. 

There are 25.4 millimeters in an inch.

Column A:  The actual measurement of the smallest diameter of this double flare gauge.

Column B:  Column A measurement in inches (calculated by dividing measurement A by 25.4 mm per inch.)  Example: 12 mm/25.4mm per inch yields .47 inches)

Column C: Column B measurement rounded to a fraction

Column D:  What column C fraction would be in hundredths of an inch (calculated by top number of column C divided by bottom number of column C)  Example: for the 12 mm row, 1 divided by two is .5 or .50 inches.

Column E:  The difference between column B and column D.

How to use this chart:

Q: I am currently wearing ⅞” gauges.  How different would the fit of 22 mm gauges be?

A: ⅞ ince is about .86mm, and 22mm gauges are about .87”diameter.  Looking in column E, you’ll see that the difference between ⅞”gauges and 22mm gauges is 0.01” or one one-hundreth of an inch.  For most people, a difference of several hundredths of a mm is not noticeable.