Card Centering Guide: What PSA 10 Really Requires
Quick answer
Centering describes how evenly a card image sits inside its borders. PSA publishes that a Gem Mint 10 must be within approximately 55/45 on the front and 75/25 on the back. A 55/45 ratio means the wider border is 55 percent of the combined border width on that axis. Centering is the most measurable part of a grade, so check it first.
What centering is
Every card has a printed image surrounded by a border. Centering is how evenly that image is positioned within the border. If the left border is wider than the right, the card is off-center left to right. If the top border is wider than the bottom, it is off-center top to bottom. Cards are measured on both axes, front and back.
Centering is the most objective part of grading. You can measure it with a ruler or an image, which is why it is the best place to start when you want to know whether a card has a chance at a top grade.
How to read a centering ratio
A centering ratio compares the two borders on one axis. Take the left and right borders:
- Add them together to get the combined width.
- Divide the larger border by the combined width to get the percentage for the wider side.
- The other side is the remainder.
So if the left border is 1.1 mm and the right border is 0.9 mm, the combined width is 2.0 mm. The wider border is 1.1 / 2.0 = 55 percent, and the card is 55/45 on that axis. If the left is 1.2 mm and the right is 0.8 mm, the card is 60/40.
Do the same for top and bottom. A card has a left/right ratio and a top/bottom ratio, and graders look at the worse of the two.
| Left border | Right border | Ratio |
|---|---|---|
| 1.00 mm | 1.00 mm | 50/50 |
| 1.10 mm | 0.90 mm | 55/45 |
| 1.20 mm | 0.80 mm | 60/40 |
| 1.30 mm | 0.70 mm | 65/35 |
| 1.40 mm | 0.60 mm | 70/30 |
The published PSA tolerance
PSA states that a Gem Mint 10 must be centered within a tolerance not to exceed approximately 55/45 on the front and 75/25 on the reverse. It also notes that graders may allow a small variance at their discretion based on overall eye appeal.
That last point is important. Centering is judged by eye as well as by ruler. A card with a dark image against a bright border makes an uneven border far more obvious than a card whose image blends into its border. Graders account for that.
Why borders on one axis can fool you
It is easy to misjudge centering by eye, for three reasons.
- Borders are thin. A difference of a fraction of a millimeter is a visible change in ratio, but it can look like nothing.
- Photos are distorted. If the camera is not square to the card, a border near the lens looks larger than one farther away.
- The image edge is not always crisp. Cards with a soft transition between image and border make it hard to say where the border starts.
Measure on a straight-on scan or photo, and if you can, measure the same card twice to check your reading.
What to do with the number
- If front centering is clearly inside 55/45 and the back is inside 75/25, centering will not be what stops a 10.
- If it is between 55/45 and 60/40, centering is likely the thing that keeps the card at 9, unless the grader exercises discretion.
- If it is worse than 60/40, centering is probably your ceiling.
Centering rarely changes. Corners, edges and surface might be arguable. Centering is a fixed fact about the card, which makes it the first filter before spending on grading. Next read how to measure card centering at home.
Frequently asked questions
What centering does a PSA 10 need?
PSA publishes a tolerance not to exceed approximately 55/45 on the front and 75/25 on the reverse, with a small amount of grader discretion based on eye appeal.
What does 60/40 centering mean?
It means that on one axis, the wider border is 60 percent of the total of the two borders on that axis and the narrower border is 40 percent. A perfectly centered card would be 50/50.
Is back centering as important as front centering?
It is judged more leniently, with PSA allowing 75/25 on the back for a 10, but it still counts. A card with an excellent front and a poor back can be held below the top grade.
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