Tips for Reading a Feeler Gauge

In order to properly read a feeler gauge, you have to know what to look for. Correct usage of the gauge will help to establish effectively sized gaps that can help engines run smoother:

The Gauge

Most of these gauges are used by mechacnics, machinists and construction crews. Mechanics find the device helpful when checking out spark plugs on vehicles. Construction workers and machinists use the device to measure gaps between 2 surfaces. Sometimes, a caliper is used for these jobs, but the gauge can measure smaller gaps.


Feeler gauges come in a certain range of sizes. They are flat metal blades, with no sharp edge, of various, measured thicknesses. They come in English and metric versions. The blades' thickness measurment is stamped on the blade.


You will need to have a pencil, paper and calculator on hand when using the gauge. This will help you to identify measurements quickly and correctly.


Use the feeler gauge to measure the size and spaces of distances. Each blade will measure in inches or millimeters. Measurement on the metric feeler gauges normally are in the hundreths or thousandths of a millimeter. The device can also determine width and depth in spaces.