Perforation: how it is measured and why it exists

Stamps · 6 September 2026

Perforation is a measurement, not an impression. It is the number of holes along a fixed length of two centimetres, and it is written as a number – 12, 12½, 14. That number is part of the stamp's identity: the same design issued with two different perforations counts as two catalogue entries, which is why identification always asks for it.

Why stamps have perforated edges at all

The first stamps were printed in sheets and cut apart with scissors, which was slow and left ragged edges. Perforation punched rows of small holes between the stamps so they could be torn apart cleanly and quickly. It is a production convenience, not decoration – which is why its details vary between printings, printers and machines, and why those variations became a way of telling printings apart.

How the measurement works

1. The unit is fixed. The gauge counts how many perforation holes fall within two centimetres. More holes in that length means a finer perforation and a higher number.
2. A gauge is just a printed scale. Rows of dots at known spacings; you slide the stamp along until one row lines up exactly with the holes. No special equipment is needed – a printed gauge on card works as well as an expensive one.
3. Line up the holes, not the teeth. Match the centres of the holes to the dots on the scale. Torn or missing teeth do not affect the reading.
4. Measure two sides. Horizontal and vertical can differ, and when they do the stamp is described with both numbers – that is a compound perforation.

The vocabulary you actually need

• Compound. Different gauges on horizontal and vertical sides, written as two numbers.
• Partial. Perforated on some sides only – normal for stamps from booklets and coils, where one or two edges were cut straight.
• Imperforate. Issued with no perforation at all, which is a separate catalogue entry and not the same as a trimmed stamp, as covered in the guide to imperforate versus trimmed.
• Rouletting. Cuts or slits rather than punched holes, leaving no paper removed – easy to mistake for damage until you know it exists.
• Perfins. Holes punched through the face of a stamp as an owner's mark, unrelated to separation.

Are perforated stamps worth more

Neither state is automatically better; what matters is which one the catalogue expects. A perforated stamp is normal, so it carries no premium by itself. An imperforate variant of a normally perforated issue is a separate entry and is often the scarcer one – but only if it left the printer that way. The same feature created with scissors is damage, and the difference is visible: genuine imperforates have wide, even margins, trimmed stamps are undersized with a wavy edge.

What perforation tells you beyond identity

• Which printing. Reprints of the same design frequently changed gauge, so the number separates printings that look identical.
• Which format. Straight edges on one or two sides point to booklet panes or coil rolls rather than sheets.
• Condition. Short, blunt or pulled teeth are condition faults, and a stamp missing teeth on one side is described that way regardless of how good the face looks.
• Centring. Perforation position relative to the design – whether the frame sits evenly inside the teeth – is judged separately and matters on classic material.

Practical notes

1. Never trim or straighten perforation. It removes evidence and cannot be undone.
2. Measure before soaking a stamp off paper – wet paper distorts and the reading changes.
3. Photograph all four edges when recording a stamp, as described in the guide to photographing a collection.
4. Record the number alongside the country and year: with those three, matching in a catalogue is quick.

Where to compare

The open archive holds 80,472 stamp images from 271 countries and territories and 6,382 Soviet issues of 1918–1991 with catalogue numbers, shown large enough to compare edges. Putting your stamp beside the archive image of the same issue is the practical way to check both perforation and centring before reaching for a gauge at all.

Open the catalogues: world stamps, Soviet stamps.