How to Use a Perforation Gauge
by Joelle Steele
When postage stamps were first introduced, they didn't have those little rows of holes along their edges that allowed you to separate the stamps easily. Stamps instead came all together on a sheet and post office clerks or users would cut them apart with scissors or make a fold between the stamps and then tear them apart along the crease line. These stamps are called "imperforates." You will find imperforate stamps in early issues of U.S. postage as well as early issues of foreign postage. In addition, some later souvenir or commemorative stamps were issued in sheets without perforations.
In 1857, the first "perforated" stamps made their appearance. Perforations — of simply "perfs" — made it much easier for a user to separate stamps that were in rolls or sheets. So, why do you need to measure a stamp's perforations? Because the number of perforations can mean the difference between two stamps (with different Scott numbers) that otherwise appear to be identical when, in fact, one is a common issue and the other is rare, making it more valuable.
Measuring perforations requires precision. For that reason, an accurate perforation gauge is a necessity for every serious collector. Sometimes you'll find these gauges printed in stamp catalogues, but those are not sufficiently accurate. You will need to purchase the most precise gauge you can find from a reputable stamp supply company, especially if you collect a lot of U.S. stamps.
When measuring stamp perforations, the size of the perforations (holes) and the number or size of the "teeth" (the paper that sticks out between the holes) are not important. What you are measuring is the number of perforations in a 2-centimeter space on a stamp. To do this, you place a stamp on the gauge and move it up and down on the gauge until the perforations on the stamp align exactly with a row on the gauge. The number next to that row will be the perforation size of that stamp. For example, a stamp with 10 perforations in a 2-centimeter space is designated "Perf 10;" a stamp with 12 perforations in a 2-centimeter space is a "Perf 12," etc.
Some stamps have a different perforation measurement on the top and bottom than on the sides. These are called "compound perforations." When the measurements are given for a compound perforation, such as Perf 11 x 10, the first number is that of the top/bottom measurement (11) and the second number is for the sides (10).
By using a perforation gauge, you can determine the value of certain stamps that were issued at different times with different perforations. Knowing which issue you have is particularly important if you plan to sell your stamp, because buyers will want to know that you have already measured the stamp and that they can therefore rely on the accuracy of its stated value.
This article last updated: 05/18/2010.