Stamp perforations are the small holes or cuts that allow collectors to separate stamps cleanly from a sheet. They are one of the most important physical characteristics in philately, helping identify printing methods, production eras, and even specific catalog numbers.
Perforations are rows of holes or cuts punched between stamps to make separation easy. The measurement of perforations is expressed as the number of holes per 2 centimeters, such as Perf 11 or Perf 14.
Perforations matter because they:
Distinguish different printings of the same design
Reveal the machinery used
Affect catalog classification and value
Below are the primary perforation styles found in world philately, each with defining visual traits.
Line perforation machines punch one row at a time. Because each row is done separately, the corners often show misalignment.
Corners may look ragged or uneven
Common in early U.S. and European issues
Produced by early pin‑based machines
Comb perforators punch three sides at once in a “Γ” shape.
Corners are neat and perfectly aligned
Faster and more consistent than line perforation
Widely used from the late 19th century onward
Harrow perforators punch the entire sheet in one pass.
Extremely uniform hole spacing
Perfectly aligned corners across the sheet
Used for high‑volume production
These are security perforations designed to deter forgery.
Holes vary in shape or spacing (e.g., alternating round and elliptical)
Common in modern European issues
Often paired with phosphor tagging
Rouletting uses cuts instead of holes.
Appears as slits, arcs, or tiny knife cuts
Found in 19th‑century issues and some modern experimental releases
Requires careful handling because edges tear easily
Imperforate stamps have no perforations at all.
Edges are smooth
Stamps must be cut apart manually
Found in early issues and modern limited editions
Collectors use a perforation gauge, a tool printed with hole patterns.
To measure:
Align the stamp’s perforations with the printed gauge holes.
Slide the stamp until the holes match perfectly.
Read the number (e.g., Perf 11, Perf 12½).
Digital gauges now allow sub‑millimeter precision using scanners or phone apps.
Perforations often determine:
Catalog number (e.g., Scott, Michel, Stanley Gibbons)
Value (perf varieties can be rare)
Authenticity (forgeries often have incorrect perforations)
Production history (different machines = different eras)
Even a difference of ½ perf can indicate a completely different issue.
Line perforation — misaligned corners, uneven spacing
Comb perforation — clean corners, consistent spacing
Harrow perforation — uniform holes across entire sheet
Syncopated perforation — alternating hole shapes or lengths
Rouletting — slits or cuts instead of holes
Imperforate — smooth edges, no holes
1840–1853 — Stamps separated by scissors
1854 — First mechanical perforator (Henry Archer)
1860s–1880s — Line perforation dominates
1890s–1910s — Comb perforation becomes standard
1920s–1940s — Harrow perforation for mass production
1950s–1980s — Security perforations introduced
1990s–Present — Digital measurement tools
Perforations are essential for identifying stamp issues.
The type of perforation reveals how the stamp was produced.
Small differences in perforation measurement can indicate rare varieties.
Modern stamps may use perforations for security as well as separation.