How to Value Stamps

Stamp collections often look valuable because they contain thousands of stamps, but most common stamps sell for very little. Value lies in details that are easy to overlook: tiny differences in perforation, watermark, color, centering and gum. This guide explains how to check them.

Last reviewed 2026-10-16 by the ValU team.

Set realistic expectations first

Hundreds of billions of stamps have been printed, and many were saved by collectors. As a result, most stamps in an inherited album, including many old ones, are common. Collections are often worth far less than the sum of their catalogue values. That does not mean a collection is worthless, but it means a careful approach pays off more than optimism.

The good news is that scarce stamps and sought-after varieties do exist in ordinary collections, and they can be identified with patience and a few simple tools.

Identify stamps with a catalogue

Stamp catalogues assign each distinct stamp a number and list its basic value in mint and used condition. In the United States the Scott Standard Postage Stamp Catalogue is the most widely used reference; Stanley Gibbons, Michel and others are used elsewhere. A catalogue number lets buyers and sellers talk precisely about which stamp you have.

Treat catalogue values as a reference point, not a price. Many common stamps are listed at a minimum value that reflects the cost of handling rather than demand, and actual sales of ordinary stamps are often well below catalogue. Scarce stamps in excellent condition can sell above catalogue.

The small details that separate common from scarce

Perforations: the number of holes per 2 centimeters, measured with a perforation gauge. Two stamps with the same design can be different catalogue numbers because of perforation alone.
Watermarks: patterns pressed into the paper during manufacture, visible with watermark fluid or by holding the stamp against a dark background.
Color shades: some stamps were printed in several distinct shades, and rare shades can be valuable. Compare carefully, as fading and chemical exposure change colors.
Printing methods and paper: engraved, lithographed and photogravure printing look different under magnification, as do different papers.
Errors: inverted centers, missing colors and missing perforations are rare and highly sought after, which also makes them a target for fakes.

Condition: centering, gum and faults

Centering describes how well the design sits within the margins. A stamp with even margins on all sides is worth more than one with the design touching or cut by the perforations. Grading terms commonly run from Poor and Fair through Fine, Very Fine and Extremely Fine to Superb, and some grading services use numeric grades.

For mint stamps, the condition of the gum on the back matters. Never hinged (often abbreviated MNH) means the gum is undisturbed. Hinged means a stamp hinge was once attached. No gum means the gum is missing. For many older stamps, never hinged examples sell at a significant premium.

Faults reduce value sharply: thins, which are areas where paper has been lifted from the back, tears, creases, short or pulled perforations, stains and repairs. Look at the back under good light and hold the stamp up to a light source to reveal thins.

Used stamps and covers

For used stamps a light, clear cancellation that does not obscure the design is preferred. Some cancellations are valuable in their own right, such as scarce town postmarks or special markings.

A cover is an envelope or wrapper that actually went through the mail. Covers can be worth much more than the stamps on them because of their postal history: unusual routes, rates, destinations or historical events. Do not soak stamps off old envelopes until you have checked whether the cover itself is interesting.

Expert certificates

Valuable stamps are frequently faked, regummed, reperforated or repaired. For that reason, buyers of expensive stamps expect a certificate from a recognized expertizing body. In the United States, the American Philatelic Expertizing Service and the Philatelic Foundation are well known; similar bodies operate in other countries. A certificate states whether the stamp is genuine and notes any faults or alterations.

The famous 1918 Inverted Jenny, a 24-cent US airmail stamp with an upside-down airplane, is a good illustration of why certificates matter: genuine examples are extraordinarily valuable and the design has been widely reproduced.

Handling and selling

Handle stamps with stamp tongs rather than fingers, store them in stock books or mounts away from humidity, and avoid tape. When selling a large collection, consider whether it is better sold intact to a dealer or auction house or broken down into individual valuable items and lots. Get more than one opinion for any collection you believe may be significant, and make sure you understand the fees and terms before consigning.

ValU can help identify a stamp and show you comparable sales, but perforations, watermarks and thins often cannot be judged from a photo. Check those details in hand before relying on any estimate.

Tools worth owning

Stamp tongs, so you never handle stamps with your fingers.
A perforation gauge to measure perforations accurately.
A magnifier or loupe of at least 5x to 10x.
Watermark fluid and a black tray, or a dedicated watermark detector.
An ultraviolet lamp, which helps identify certain paper types, tagging and repairs.
A current catalogue for the countries you collect, in print or online.

You do not need all of these on day one. Tongs, a magnifier and a perforation gauge are inexpensive and will let you identify most stamps correctly.

Common mistakes when valuing stamps

Adding up catalogue values and treating the total as the collection's market value.
Soaking stamps off covers that might be more valuable intact.
Missing thins and repairs by looking only at the front of the stamp.
Assuming that a stamp is rare because it is old or from a distant country.

Dealing with an inherited collection

If you have inherited albums, keep them intact while you assess them, because an album's arrangement can carry useful information and collectors sometimes value complete, well-organized collections. Note the countries and periods covered, look for any stamps the previous owner kept separately in envelopes or protective mounts, and check for certificates or purchase receipts. Then ask a local stamp club or a reputable dealer for a general opinion before deciding how to sell.