How Card Grading Works
From intake to slab, grading follows the same core process at every company. Here is what graders actually inspect, how the number is assigned, and why population reports matter.
The Four Things Graders Inspect
Every major grader evaluates the same four attributes. Centering measures how evenly the printed border frames the art, checked separately on the front and the back and expressed as a ratio like 55/45. Corners are inspected under magnification for whitening, rounding, or dings. Edges are checked for nicks, chipping, and whitening, which black-bordered Magic frames reveal brutally. Surface covers scratches, print lines, scuffs, indentations, and, on foils, clouding or curl. Alongside condition, graders authenticate the card, confirming it is genuine and unaltered, which is a core part of what a slab certifies.
How the Grade Is Assigned
Graders combine the four attribute reads into a number on the 1-to-10 scale. PSA issues a single overall grade with no published subgrades, and in practice a card is capped by its weakest attribute, so one soft corner can hold an otherwise flawless card at a 9. BGS and CGC score each attribute and can print those subgrades; BGS then applies a weighted formula, where a card generally cannot exceed half a point above its lowest subgrade. Multiple graders and quality-control passes reduce individual bias, but there is always some subjectivity, which is why the same card can grade differently across companies or even on a resubmission.
Encapsulation and the Label
Once graded, the card is sonically or mechanically sealed in a tamper-evident slab with a label that records the card, set, grade, any subgrades, and a unique certification number. That cert number ties back to the grader's online database so buyers can verify the slab is real and matches its label. The holder both protects the card and locks in the certified condition, which is a big part of why graded cards trade with more trust than raw copies in a market that has to worry about counterfeits and alterations.
Population Reports
Each grader publishes a population report: a running count of how many copies of a given card exist at each grade. Pop reports are the closest thing to hard scarcity data in the hobby. A card with only a handful of 10s is far rarer in top condition than one with thousands, and that scarcity drives price. Before or after grading, check the pop report to gauge how special a high grade really is. To connect that scarcity back to money, scan the card in Tappr for its live raw price and printing details, then read the pop report to judge how much a top grade could add.
Common questions
01 What do card graders inspect?
Graders evaluate four attributes, centering, corners, edges, and surface, on both the front and back, and they authenticate the card as genuine and unaltered. Foils are also checked for clouding and curl, and black borders are scrutinized for edge whitening.
02 How is a card grade decided?
The four attribute reads combine into a 1-to-10 number. PSA issues one overall grade capped in practice by the weakest attribute, while BGS and CGC score each attribute; BGS applies a weighted formula that keeps the overall within half a point of the lowest subgrade.
03 What is a population report?
A population report is the grader's running count of how many copies of a card exist at each grade. It is the best available scarcity data, since a card with only a few 10s is far rarer in top condition than one with thousands.
04 Why can the same card get different grades?
Grading involves some subjectivity even with multiple reviewers and quality-control passes. Slight differences in centering tolerance or surface scrutiny between companies, or between submissions, can move a borderline card up or down half a point.
Related Grading Guides
Scan Your Cards Before Grading
Get Tappr free. Identify any Magic: The Gathering card and see what it is worth in seconds.
No credit card. No signup. Just scan.
Scan to download
Point your phone camera at a code
