How stamp grading works: the 0–100 scale explained

When collectors talk about a stamp's "grade," they mean a quality score assigned by a third-party grading service after examining the stamp under magnification and good light. In the United States the best-known service is Professional Stamp Experts (PSE), and the numeric scale most U.S. collectors use runs from 0 to 100, with assigned grades from 5 (Poor) to 100 (Gem). In practice, the grades you'll see on desirable stamps cluster in the upper part of that range, from 70 to 100. When this guide and the Philatelic.ai PreGrader focus on that premium 70-to-100 band, it's because that's where collectible value is decided; the full scale runs lower.

Who grades stamps, and does PSA?

PSE (Professional Stamp Experts) is the service most U.S. collectors mean by stamp grading, and its 70-to-100 scale is the one used throughout this guide. The Philatelic Foundation also grades and expertizes U.S. stamps. A frequent question is whether PSA grades stamps; it does not. PSA is known for trading cards and coins, and although it shares a corporate parent with PSE, numeric stamp grading is the domain of PSE and the Philatelic Foundation, not PSA.

The stamp grading scale: what the numbers mean

On the PSE grading scale, each number maps to a long-established quality tier. The common grades and their names are:

• 70, Fine. A sound, presentable stamp, but noticeably off-center or otherwise modest in appearance.
• 75, Fine to Very Fine. A step up from Fine, not yet a clean VF.
• 80, Very Fine (VF). The benchmark "nice" grade; balanced but not exceptional.
• 85, Very Fine to Extremely Fine.
• 90, Extremely Fine (XF). Clearly above average, with strong centering and margins.
• 95, Extremely Fine to Superb. Excellent in nearly every respect.
• 98, Superb. Very few flaws; the kind of stamp that stands out across a dealer's stock.
• 100, Gem. As close to perfect as the issue is found.

Grades below 70 exist, but most collectors lump them together as "low grade" because the price differences down there are small. The action (and the money) happens from 90 upward.

What graders actually look at

PSE's system weighs three things together: centering, soundness, and eye appeal (color, freshness, and impression). Centering and soundness are the primary drivers; eye appeal then nudges the grade up or down.

Appearance

• Centering is the single biggest visible driver of most grades. It's how evenly the design sits inside the four margins. (We cover this in depth in stamp centering explained.)
• Margins: their size and balance around the design.
• Color, freshness, and impression: how bright and crisp the stamp is.
• Cancellation, for used stamps: a light, neat cancel is preferred to a heavy smudge.

Soundness

A beautiful stamp with a hidden problem will not earn a high grade. Graders check for faults such as thins, tears, creases, pulled or short perforations, stains, and gum problems (hinging, disturbance, or regumming on mint stamps). A single confirmed fault can cap a stamp far below what its centering alone would suggest.

The "J" for Jumbo stamps

Occasionally a stamp has margins so unusually large and balanced that it earns a Jumbo designation, written as a "J" after the grade (for example, 95J). Jumbos are prized because oversized margins are rare and visually striking.

Why one point matters

Grading exists because tiny differences in quality translate into large differences in price. For a scarce stamp, the jump from a 95 to a 98, or from a 98 to a 100, can multiply the value several times over, because so few examples survive in that condition. That's also why grading is worth paying for only on the right stamps, a topic we cover in is your stamp worth grading?

What a photo can't show

Some of the most important factors in a real grade, such as thins, regumming, and gum disturbance, often don't show up in any image. That's a hard ceiling for any photo-based assessment, including ours: it's why an image-based pre-grade should be read as an informed estimate of visible condition, not a guarantee. The certified grade from a professional service is always the real answer.

Where pre-grading fits

That is exactly the gap the PreGrader closes. Predicting a grade yourself is hard because it isn't a single measurement: it blends centering, soundness, and eye appeal, and even expert graders bring some human judgment to the call. The PreGrader was trained on nearly 250,000 stamps already graded by PSE, so it has learned how those factors combine, and how human graders actually score them, then turns that into the most probable grade plus the full range of likely outcomes from a single scan. So instead of guessing where your stamp falls on the scale, you get a calibrated read of the likely grade, before you invest in a professional assessment.