Scott Catalog Numbers: How to Read a Stamp Listing

A Scott number is the identifier that turns "an old blue stamp with a man on it" into a specific catalogue entry with a year, a printing, a perforation, a watermark and a price. In the United States, Canada and Mexico it is the numbering everyone uses; dealers quote it, auction lots cite it, and album spaces are laid out by it.

The catalogue has been published since September 1868 and now runs to fourteen volumes: twelve covering every country that has ever issued stamps, plus the US Specialized and Classic Specialized editions for collectors who need the sub-varieties. It is published by Scott Stamp LLC, which acquired it from Amos Media in October 2025.

A full listing gives the Scott number, an illustration, the denomination, the colour of the paper and design, a description of the design, the year of issue, and prices for unused and used examples. That is enough to confirm what you have — provided you also check the things the picture cannot show you, which is where most misidentifications happen.

A plain number with no letter in front is a regular postage stamp. A capital letter before the number marks a different class of stamp:

• C — air post (airmail). The Inverted Jenny is Scott C3a: the third US airmail stamp, variety a.
• B — semi-postal, a stamp sold above face value with the surcharge going to a cause.
• Other prefixes and prefix combinations cover postage due, special delivery, occupation issues, postal tax and similar categories.

This matters in practice because the same number can exist twice. Scott 3 and Scott C3 are different stamps from different series, and quoting one when you mean the other will get you the wrong price and the wrong stamp. Always copy the prefix.

Letters after the number work differently from letters before it, and this is where people most often misquote a catalogue.

A capital-letter suffix marks a major listing in its own right. Scott 28A is a major number, printed in the larger type the catalogue uses for main entries, and is a distinct stamp rather than a footnote to Scott 28.

A lowercase suffix marks a minor listing: a shade, a printing variety, an error, an imperforate pair. Minor listings appear in smaller type beneath the major entry.

The two stack, and the order is fixed. A minor variety of Scott 16A is Scott 16Ab, not Scott 16b — the capital comes first because it belongs to the major number, and the lowercase letter is added after it. Scott 16b would be a minor variety of Scott 16, a different stamp.

If a seller quotes a number that does not follow this pattern, the listing is worth checking before the price is.

Scott values are retail figures for a stamp in a grade of Very Fine, unless the listing says otherwise, and they are set from market analysis and reported sales over the previous year. They are not what a dealer will pay you, and they are not what a stamp in average condition is worth.

Gum assumptions are built in. For pre-1900 issues, an unused stamp priced at the listed figure is expected to retain most of its original gum; for later issues, full original gum is assumed unless the entry states otherwise. A stamp without gum, or regummed, sits well below the listing.

A minimum value of about 25 cents applies to most stamps. That floor exists to cover a dealer's cost of handling, not to describe demand, and it is why totalling the catalogue value of a bulk lot produces a meaningless number.

Stanley Gibbons, the British catalogue first issued as a penny price list in November 1865, works differently on this point: its prices are what the firm would itself charge for that stamp in that condition if it had one in stock, rather than an average of the market. Two catalogues can therefore give two different figures for the same stamp without either being wrong. See the stamp appraisal page for how these figures relate to what you will actually be offered.

Matching the picture is the easy part and the unreliable part. Most catalogue numbers that look alike are separated by things you have to measure.

Work in this order: country first, then the series and year, then the perforation gauge, then the watermark, then the shade, then condition. A stamp that matches the illustration but has the wrong perforation count is a different Scott number with a different price, sometimes by three orders of magnitude. Our guide to perforations and watermarks covers the two measurements that do most of the work, and identifying a stamp's country and issue handles the first step for foreign material.

Photograph the stamp and the app identifies it, which gets you to the country and issue quickly. Take the measurements yourself before you settle on a catalogue number, because the number is what everything else — price, certificate, sale — is hung on.