How to measure card centering

What the numbers mean

Centering compares the two borders on each axis. Add the left and right borders together, and the wider one's share of the total is the first number. A card with a 3.4 mm left border and a 2.6 mm right border is 3.4 out of 6.0, or 56.7%, written 56.7/43.3. Perfect centering is 50/50.

Do the same for the top and bottom. Say those are 3.1 mm and 2.9 mm: 51.7/48.3. The card is held to its worse axis, so this one is a 56.7/43.3 card, and that's the number to check against a grading company's limits.

Only the ratio counts, so the unit doesn't matter. Millimetres, sixty-fourths of an inch or pixels in a photo all give the same answer, as long as all four borders are measured the same way.

Where a border starts and ends

• Outer edge: the cut edge of the card itself.
• Inner edge: where the printed border meets the frame or the picture. If there's a thin frame line, measure to it. If there's small print in the bottom border, like a copyright line, measure past it to the frame.
• Where on the side: in the middle, away from the rounded corners. If a border is wider at one end than the other, the print is a little tilted. Write down both ends and plan around the worse one.
• Full-art cards have no border, so there's nothing to measure this way.

Three ways to measure

A ruler and a loupe

Use a steel ruler marked in half millimetres and a jeweller's loupe. Lay the ruler across the border at the middle of the side, line its zero up with the card's edge under the loupe, and read where the border ends. You can estimate a quarter of a millimetre between the marks with care. Measure all four sides the same way, then do the arithmetic above.

A printed template

The free card centering template prints card outlines at true size with a line every half millimetre from each edge. Print it at 100% on a transparency, lay an outline on the card's edge, and count lines to the printed border. A check bar on the sheet tells you whether the printer scaled it.

A straight-on photo

Put the card on a plain, flat surface and shoot from directly above, with the card filling most of the frame. Zoomed in on a screen, a photo shows the borders far bigger than a ruler can. The catch is the angle: a phone tilted even a little makes the near border look wider. Load the photo into the calculator and drag its lines onto the edges.

How much a millimetre matters

Borders are thin, so small differences move the ratio a lot. On a card whose left and right borders add up to 6 mm:

• If the print sits a tenth of a millimetre to one side, one border gains what the other loses, and the ratio moves about 1.7 points: 3.1 against 2.9 is 51.7/48.3.
• Half a millimetre to one side, 3.5 against 2.5, is already 58.3/41.7.
• Misread just one border by half a millimetre, a ruler's smallest mark, and the ratio is off by about 4 points.

So a ruler alone can tell a badly off-center card from a good one, but it can't tell 54/46 from 57/43. For a card near a limit, read it under a loupe or from a straight photo before deciding.

Holding it against the limits

Each grading company publishes the worst centering it allows for each grade, front and back. On the front, PSA asks about 55/45 for a 10 and 60/40 for a 9. CGC and SGC publish the same two figures for their Gem Mint 10 and 9. Beckett is stricter at the top: 55/45 both ways for a 9, and 50/50 all round for a Pristine 10. The card centering chart has every grade on one page.

The 56.7/43.3 card above misses 55/45 and passes 60/40. Going by centering alone, it could be a 9 at PSA, CGC or SGC, and an 8 at Beckett, which asks 60/40 for an 8.

Backs are allowed much more. PSA's back limit is 75/25 for a 10, so a back that measures 4.2 mm against 1.8 mm, which is 70/30, is fine there. Beckett asks 60/40 on the back of a Pristine 10, and SGC publishes no back limit at all.

Two things to keep in mind. These limits are guidelines: PSA's own scale says “approximately” and allows a small variance for eye appeal. And centering is one part of a grade. Corners, edges and surface can only pull a card lower. We aren't affiliated with or endorsed by PSA, Beckett, CGC or SGC.

Let the phone do the measuring

Dead Center, our app, does all of this from a photo. It finds the card's edges, flattens a tilted photo so the angle can't skew the borders, measures all four, and gives each reading a ± for how sure it is. It shows the best grade centering alone allows at each company, and sorts a stack of cards into a grading plan. It's free on Google Play.

▶ Get it on Google Play Coming soon to the App Store

Deciding whether a card is worth sending at all? The is it worth grading? calculator weighs its raw price against what grading costs.