Artificial intelligence for your stamp collection

perf48 Database User Guide

perf48 is a cloud-based database of worldwide stamps offered as a service, designed for an analytical, data-driven stamp collector.

Designed to work without photos, it changes the paradigm of identifying stamps from one of finding to one of filtering. Instead of eyeballing a page looking for a picture, you browse the full chronological listing, and/or filter search results until the stamp can be identified. For instance, you first filter by country, then perhaps by denomination, then by the depicted topic, finally by year. Filters continue to be applied until a positive identification is made.

You'll need a free perf48 account to search the database. We respect your privacy, collect the minimum amount of information to maintain an online account, store no personally-identifiable information other than an email address, will rarely contact you and do not share our member list with others.

Select a country and the database will automatically display, starting with the first set. You can start browsing the list, or apply over 10 kinds of filtering criteria, such as denomination, keyword, topic, year, overprint, etc.

The first one hundred stamps will initially display. To see more, click "more results" at the bottom of the page. Up to one thousand stamps can be returned in a query. A quick way to see beyond the first thousand results it to use the year pick list. Select the last year displayed in the first thousand results, and then select the > symbol to see the next thousand results.

It is a simplified catalogue; one row per face-different stamp. For instance, a stamp issued with multiple watermarks is listed once, with an icon indicating a watermark variety exists. The listed stamp represents the most common iteration.

Filtering Criteria


The country pick list displays countries of the world.

perf48 uses a 2-level hierarchy for classifying countries and other entities which issue stamps. The top level is Country, and is generally a list of present-day countries, although some dead countries and miscellaneous groupings of countries are used. Organised under a country is a "stamp-issuing entity," which is what you click on in the Country pick list. To find a stamp- issuing entity, look under the present-day country, not under the country which may have issued the stamp. For example, Canal Zone is listed with Panama, not the United States, because the Canal Zone territory is within present-day Panama. The fact Canal Zone was American territory when it was issuing stamps is not the basis of how perf48 groups stamp-issuing entities. Thus, occupation stamps appear with the territory occupied, not the occupying force.

perf48 uses a few special groups as countries. Large, multi-colony colonial-era administrations such as French Equatorial Africa, French West Africa, Ruanda-Urundi, Portuguese Africa, etc., are grouped under a "country" called "Africa – Colonial." The four Antarctic territories, Australian, British, French Southern & Antarctic, and Ross Dependency are grouped under a country called "Antarctica." All of the Grenadines belonging to both Grenada and Saint Vincent are grouped under one country called "Grenadines." A few other naming conventions: For Russia 1917-1990, see Soviet Union. For Great Britain, see United Kingdom. For Burma, see Myanmar. For Ivory Coast, see Cote d'Ivoire.

Unique Identifier

Each stamp is listed by a unique identifier made up of an ID for the stamp-issuing entity, a set number and a stamp number, connected with a dot. The first stamp issued by a given country is 1.1. The second stamp issued in the first set, if there is one, is 1.2. The first stamp in the second set is 2.1.

For instance, the 4 pence 1912 definitive of South Africa is 20250.2.5, or commonly referred to as "South Africa 2.5." This is broken down as follows:


Denom, short for denomination, is the value or rate shown on the stamp.

As a database, perf48 takes a digital approach to denoms. Trailing zeroes are dropped, so $1.80 is 1.8. All fractions are decimalised: 1¼ is listed as 1.25. For mixed denoms, common in British Commonwealth stamps, the denom appears as a decimal even if it is pre-decimal currency, so one shilling three pence is displayed as 1.3 s. Half-pennies are 0.5 p.

Stamps with a rate rather than a value, such as "first class" are listed as "fc" or a "1" or an abbreviation for how the rate is inscribed on the stamp.


perf48 uses an abbreviated designator of the currency. It is usually a single letter representing the first letter of the name of the currency, but multiple letters may be used for clarity if two currencies start with the same letter. So, dollars are "d", cents are "c", pence (both pre- [denarius] and post-decimal) are often "p" especially if the country later issued dollars where "d" is used; pfennig is "p"; euro is "e"; etc. For clarity, pound is abbreviated "po" or spelled out when pence are also used by the same country. Currency symbols such as $, €, £ are not used.

The denomination and currency fields are separate, enabling searching by denom across all currencies when the currency is unclear.


Description is a brief keyword or other text describing the stamp. Where two or more stamps in the same set have the same denom, a clarifying note is often added to the end of the description, such as "QEII green" vs. "QEII purple." Surcharges often have a description of "surcharge on 25c".


The year is usually the year the stamp was first issued. There are options to search before or after a specific year.


perf48 uniquely offers two topic fields: topic depicted and topic commemorated. perf48 classifies all stamps into one of ~700 topics; the topic pick lists are filtered to only topics issued by the country selected.

British monarchs are referred to by acronym: QV (Victoria), KEVII (Edward 7th), KGV (George 5th), KGVI (George 6th), QEII (Elizabeth 2nd). Pre-independence definitive sets use these acronyms as the value for the topic commemorated field. Other common acronyms used in the database include: WWII, ITU, ICY, IEY, IYC, IYD, ILO, IOC, UN.


Mint and used reference values are displayed. Values reflect condition common for the country.


There are two type fields. The first enables filtering based on a stamp being a definitive versus commemorative. If you're trying to find a commemorative, this feature removes all definitives from your search results, and vice versa.

A separate pick list is labelled "type," and this enables filtering based on the role the stamp served, such as semi-postal, air mail, postal tax, etc. perf48 displays stamp sets chronologically regardless of type, rather than breaking up sets and moving certain types to the end of the list; what some collectors call "back of the book" sections. Stamps other than regular issues are flagged with a symbol (for instance, a "+" symbol for semi-postals & an airplane symbol for air mail) to make them easy to spot in the listings. Hover your mouse over the symbol to see its exact type. To omit these types and only view regular issue stamps ("front of the book"), select "standard" from the Type pick list.


The attribute pick list contains up to 15 attributes which a stamp may have; this makes identifying stamps with notable features a breeze. A stamp possessing any of these attributes is flagged with a tag symbol; hover your mouse over the symbol to see which attribute the stamp has. The attribute pick list includes: souvenir sheet, booklet, sheet, pair, strip/block, selvage/label/tab, triangular shape, diamond shape, circular, other shape, embossed, hologram, 3D, scented and specimen.


Stamps with varieties are face-same stamps with one of 15 varieties which some collectors consider different stamps. perf48 is a simplified database, with one database record for each face-same stamp. Stamps issued with varieties are flagged with a symbol of a block of 4 black squares, alerting collectors to instances where they may own more than one stamp for a given database record. Hover your mouse over the symbol to see the variety. If you own two or more copies of this stamp because you want to collect the varieties, simply click the + symbol in the Own column more than once to indicate how many varieties you own. (See "Own" below.)


If a stamp set is continued in a separate listing, a link icon appears. Hover your mouse over it to see the next set number where the set is continued.


You can track your collection in the cloud with a full perf48 membership. When you are logged in to your membership account, two additional fields appear in the search results: Own and Want. If you own the stamp, click on the "+" button in the mint and/or used column. If you own more than one copy of this stamp, such as two varieties (see varieties, above), click "+" again to increase the quantity. Memberships are USD$2.48 per month.


To bookmark a stamp, click the tick box in the Flag column.


Above the search results, analytics are displayed showing statistics about your query.

To see how many stamps you own for a given country, select the country and filter on "Own."

To see your want list, pick a country and filter on "Want."