How to measure perforations

Sometimes two stamps look alike and the only difference is the gauge of the perforations.  Perforations are small rows of holes punched between stamps to make them easier to separate.  We use a perforation gauge to measure the number of holes or teeth within two centimeters. If a stamp has 11 perforations in 2 cm, we say it’s “Perf 11.” Here are some tips on how to measure perforations:

  1. To measure your stamp, lay it on the center of your gauge.
  2. Slide the stamp up or down until the perforations on the stamp line up with the pattern on the gauge all the way down the length of the stamp. (If the perforations only line up with the gauge part of the way, then you haven’t found the correct gauge yet – keep trying!)
  3. Be sure to measure one horizontal side and one vertical side of the stamp, since many stamps have what is called “compound perforations.”They have a different perforation gauge on the horizontal and vertical sides. In catalogs, the horizontal perforation gauge is listed first, then the vertical.  For example, the 1984 Winter Olympic stamps (US #2067- 70) measure perf 10½ x 11. That means there are 10½ perfs every 2 cm on the horizontal sides and 11 perfs every 2 cm on the vertical sides.

If you need a perforation gauge, click here to get the long-lasting aluminum gauge pictured above.  Other options include Linn’s Multi-Gauge and Precision US Specialty Multi-Gauge.

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    1. Hi Ray,

      The simple answer is “you don’t.” There are very few round stamps and they are easy to identify by other means, such as design. If the USPS begins issuing look-alike circular stamps, perhaps new means of measuring perforations will need to be found. I hope this helps.

      Happy Collecting!

  1. Where do I find a perforation gauge that will tell me the difference between a 9.9 perf stamp and an 9.75 perf stamp? I am at a complete loss because my 2 gauges do not have those measurements.

    Thank you.


  2. Sometimes I’d swear that the stamp must lie somewhere between the established half-sizes, e.g. 10 1/4 and not 10 or 10 1/2. Is that at all possible, or do those that set up the perforation machines stick with the half-sizes seen on the gauges available to us? Does anyone have an answer to this? I’d like to know.

  3. Stupid question here, but why can’t you just count the perforations with the naked eye?my mom just gave me a box filled with great grandfathers stamp collection, stamps from the early 1900s to 1970s there are thousands of stamps, all labeled. It is fascinating. I am just getting my feet wet on stamp collecting, it is comprehensive but fascinating.

    1. The gauge of the perforations is the number of holes in 2cm of stamp edge. Counting them won’t work unless the stamp is exactly 2cm wide or high or both if it has to be measured both directions.

  4. I have one of the most highly prized U. S. Stamps of the 20th century very much the same as pictured in the Mystic album. By Gary Griffith Vol. 12 #. It says in 1924, coil waste stamps accidentally perfect 11 both vertically & horizontally were distributed. I’ve counted it several times but it’s more than 11 perforations are in the vertical sides same w/my stamp. How do we determine if I have the Franklin stamp which is very much the same as in their picture?

    1. Perf 11 means that there are 11 perforations in 2 cm – not the entire length of the stamp.

  5. Hi there is 2 perfs on 50p UK machine stamp booklets first is Perf P the other is perf e how can I tell what is what

  6. A perforation with small holes and teeth close together is called a fine perforation ; one with large holes and teeth far apart is called a coarse perforation; and one in which the holes are not clean cut, but jagged, is called a rough perforation. In some cases the gauge of the perforations on the side of a stamp differs from that of the top and bottom, and such stamps are said to have compound perforations. In measuring compound perforations the gauge of the top is usually given first and then the gauge of the sides of the stamp. The process of stamp separation is mechanical, that is why many things can go wrong causing some philatelic errors and oddities. In such a way so called blind perforations have appeared. These are the perfs that occur when a hole is not completely punched out. The stamp collectors may also find the off-center perfs that cut into the design of the stamp. One more oddity may appear when a stamp has different perforations on opposite sides. The philatelic items that have some errors in their perforations are often called misperfs.

  7. Dear Stamp Personnel,
    I am unable to use my perforation guide to obtain the numbers so that I can distinguish between sizes (e.g. the difference between 10 and 11 perforations). They both look alike. How does a person use this guide?

    1. When you put a perf. 11 stamp along the perf. 11 on the gauge, the perfs will line up for the entire length of the stamp. If you put it on the perf. 10 line of the gauge, it will not line up evenly the entire length of the stamp.

      We plan to improve the information in this post in the near future. I hope this info helps.

  8. If the Scott book specifies that the perf is 10,11,12 etc.. Is that automatically considered it measured vertically since it doesn’t specify anything different like some others do.

    thank you

    1. If Scott only lists one perf size, that’s the perf size on all four sides of the stamp. If it’s a coil, it’ll say 10 horizontally or 10 vertically. If it’s two different perf sizes, it’ll say 10 vertical, 11 horizontal.

  9. I have a pair of Ben Franklin stamps on a postcard, they only have perfs on top and in the middle, mm are 18.5 X 23.5.the stamps look great, they are green. Is this a rare position set of stamps? Postmark says 1925, that is all i can read on the card, where was posted i do not know. I am not an expert I just love to work the stamps.

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