Guide · Centering basics

How to measure trading card centering

Centering is the one grading factor you can actually measure before you submit. Here is how the numbers work and how to get them right.

Updated September 26, 2026 · 7 min read

What "centering" means

Every card has a physical edge (where it was cut) and a printed frame (the edge of the design). The space between them is the border. When a card is cut perfectly, the left border matches the right border and the top border matches the bottom one. When the cut drifts, one border gets wider and the opposite one gets thinner. Centering describes how uneven that split is.

Centering is written as two numbers that add up to 100, such as 55/45 or 60/40. A perfect card is 50/50. The further the numbers move from 50/50, the more off-center the card is.

The formula

For each axis, divide one border by the sum of both opposite borders:

You do the same for the vertical axis with the top and bottom borders. The unit doesn't matter (millimetres, pixels, sixteenths of an inch) as long as you use the same one for both borders, because only the ratio counts.

Worked example

The left border of a card measures 3.0 mm and the right border 2.0 mm:

Then the top border measures 2.4 mm and the bottom 2.6 mm: 2.4 ÷ 5.0 = 0.48, so the card is 48/52 top to bottom. The card's centering is limited by its worst axis, the 60/40, because that's the one a grader will hold against it.

Front and back are measured separately

Graders look at both sides, and they are more lenient on the back. PSA, for example, publishes about 55/45 to 60/40 on the front and 75/25 on the back for a Gem Mint 10. Always measure both sides: a card with a perfect front can still be held back by a badly cut reverse. See our centering standards guide for the full tables.

Three ways to measure

1. Ruler or calipers

A millimetre ruler is too coarse for borders this thin. Digital calipers are better, but their jaws can scratch the card or dent an edge, and it's hard to hit the printed line exactly. Use them only on cards you don't plan to grade.

2. Transparent centering overlays

Plastic overlays with printed guide lines are quick and don't touch the card surface, but you read the result by eye. They're fine for spotting obvious 70/30 cards and weak at telling 55/45 from 60/40.

3. Digital measurement from a photo

A straight-on photo lets you zoom far beyond what your eye can do and place lines on the exact edge. This is the most precise option available at home, as long as the photo is taken correctly (see how to photograph cards for centering).

Step by step with CardCenter Pro

1. Upload the front photo. Auto-align straightens the card and places the eight guides: amber on the physical edges, cyan on the printed frame.
2. Check each line with the loupe. Turn the loupe on and hover each guide. If a line sits even slightly off the edge, drag it, or select it and use the arrow keys for fine moves.
3. Use the contrast filter on hard edges. Silver or holo borders and low-contrast frames are easier to see in the Contrast or Invert view.
4. Repeat for the back. Switch to the Back tab and upload the reverse. The panel then shows a combined verdict for both sides.
5. Export the report. The PNG report shows the photo, the guides and the numbers, ready to attach to a listing or keep with your submission notes.

Common mistakes

• Angled photos. If the phone isn't parallel to the card, the far border looks thinner than it is. This "keystone" effect can invent 5 to 10 points of error.
• Measuring to the rounded corner. Measure the straight sides near the middle of each edge, not at the corners, where the cut curves.
• Choosing the wrong inner line. Pick one printed feature, usually the edge of the coloured frame, and use the same feature on all four sides.
• Measuring through a toploader. Thick plastic adds glare and refraction. A thin penny sleeve is usually fine; a scratched toploader isn't.
• Trusting one decimal. A result of 60.4/39.6 is not meaningfully different from 59.6/40.4. Near a limit, treat the card as borderline.

What about full-art and borderless cards?

Many modern cards have art that runs to the edge with no clear frame. Graders still judge centering on these, usually by the position of printed elements such as the text box, the set symbol or an inner border line. Choose a feature that is printed in the same position on every copy of that card and measure all four sides to it.