Centering is the one thing about card grading you can measure. Everything else is a judgement about how a card looks. Centering is a ruler and some arithmetic.
Which is why it is strange that the numbers everyone uses are not published anywhere by PSA.
I went looking, because 2,236 impressions a year reach this site from people searching for centering tolerances, and they arrive at an average position of 10.5. That is the worst-ranking cluster in my entire PSA topic, which usually means the page they land on does not really answer them. It does not. So here is the page that does, including the part where I tell you the numbers are inferred.
What the ratio actually means
Centering is expressed as a ratio comparing opposite borders. 55/45 means one border takes 55% of the total border width and the opposite one takes 45%.
It is not a percentage of the card. It is a percentage of the border pair.
Work it out like this:
- Measure the left border and the right border. Call them L and R.
- Add them together.
- Divide the larger by the total, times 100.
A card with a 2mm left border and a 1.6mm right border: total 3.6mm, larger side 2mm, so 2 ÷ 3.6 = 55.6%. That is a 56/44 card. Repeat top to bottom, and your centering is the worse of the two.
Perfect is 50/50. The further from 50, the more obviously the art sits off to one side.
| Ratio | What it looks like |
|---|---|
| 50/50 | Dead centre |
| 55/45 | You have to look for it |
| 60/40 | Noticeable if you know to check |
| 65/35 | Visibly off to most people |
| 70/30 | Obviously crooked at a glance |
| 90/10 | One border nearly gone |
The tolerances everyone uses
Here is the table that circulates everywhere, including in my own PSA grading guide.
| Grade | Front | Back |
|---|---|---|
| PSA 10 | 55/45 | 75/25 |
| PSA 9 | 60/40 | 90/10 |
| PSA 8 | 65/35 | 90/10 |
| PSA 7 | 70/30 | 90/10 |
Note how much looser the back is. PSA cares about the front because that is what people look at, and a card can have a badly centred back and still gem. This surprises people constantly, and it is the single most useful line on this page: stop worrying about your back centering unless it is really bad.
Now the awkward part
Those numbers are not on PSA's published grading standards page.
I read it looking for them. There are no numeric centering tolerances on it, for any grade. What there is instead is this:
The other component of grading is somewhat subjective. The best way to define the subjective element is to do so by posing a question: What will the market accept for this particular issue?
The 55/45 figures circulated in older PSA material and have been repeated by every guide since, mine included. They match observed grades closely enough that the hobby treats them as policy. They are not currently presented as policy by PSA.
I want to be careful about the claim I am making. I am not saying the numbers are wrong. I am saying I could not verify them from PSA's current public documentation, and that no guide quoting them, including my old one, tells you that. If PSA publishes these tolerances somewhere I could not reach, I would genuinely like to be corrected, and I will update this page.
Measure it yourself before you spend anything
Whatever the exact tolerance, centering is the one criterion you can check at home for free. Do this before you pay $79.99 a card to find out.
With a ruler. Digital calipers are better, a steel ruler with millimetre markings is fine. Measure at the middle of each border, not near a corner, because corners round slightly and will lie to you.
With a scanner. Scan at 600dpi and measure in pixels in any image editor. Far more accurate than a ruler and it gives you a record.
By folding a strip of paper. No tools at all. Cut a strip the width of the card's total border pair, fold it exactly in half, and lay it against the borders. If the fold does not sit on the art edge, you can see immediately which way it is off and roughly by how much.
Whatever you use, measure the front twice, in both axes. The worse of the two is your centering.
A worked example
Take a card that measures like this on the front, in millimetres:
| Border | Measurement |
|---|---|
| Left | 2.10 |
| Right | 1.62 |
| Top | 1.88 |
| Bottom | 1.79 |
Left to right: total 3.72, larger side 2.10, so 2.10 ÷ 3.72 = 56.5%. That is 57/43.
Top to bottom: total 3.67, larger side 1.88, so 1.88 ÷ 3.67 = 51.2%. That is 51/49.
Your centering is the worse of the two, so this card is a 57/43. Under the commonly quoted tolerances that is outside the 55/45 usually cited for a 10 and comfortably inside the 60/40 cited for a 9. Vertical centering is near perfect and contributes nothing, which is the point people miss: one bad axis is enough.
Note also how small these numbers are. The difference between a 57/43 and a 53/47 on this card is under a quarter of a millimetre of border. That is why eyeballing does not work, and why a scan beats a ruler.
What centering does not do
Two things worth knowing, because they save arguments.
Centering does not average with other criteria. Your grade is essentially capped by your worst category. Perfect corners, edges and surface with 70/30 centering does not average out to a 9. The centering is the ceiling, exactly as whitening on a corner is a ceiling.
A miscut is not bad centering. If the factory cut ran so far off that another card's border appears on yours, that is a miscut, and PSA has a separate designation for it: "N8 - Miscut - This term is used when the factory cut is abnormal for the issue." Miscuts sometimes carry a premium with collectors, which is the opposite of how bad centering behaves.
There is also the OC qualifier, where PSA grades the card on everything else and attaches a note that it is off-centre. A card with a qualifier sells for less than a clean grade at the same number, and more than the low grade its centering would otherwise have forced.
Where my own theory gets shaky
Consistency implies a standard. PSA's centering calls are consistent enough that people build centering calculators and tolerance charts and they work. Something is standardising this. Saying "it is not published" is a statement about documentation, not about whether a rule exists inside the building.
Older cards get more room, and I cannot quantify it. Everyone in the hobby agrees vintage is judged more leniently on centering than modern, because the print quality was worse and the market adjusted. I believe that. I cannot give you a number for it, and anyone who does is guessing.
I have three cards. One of them, per my old notes, measured about 58/42 on the front and still came back a 9. That is consistent with a 60/40 tolerance. It is also one card.
The thought I keep landing on
Centering is the only part of grading that a machine could do perfectly, and it is the part people obsess over most, and those two facts are related. It gives you a number, and a number feels like control.
But the card was already off-centre when it came off the press. You did not do it, you cannot fix it, and no measurement changes what it is. All the ruler tells you is whether it is worth eighty dollars to have someone else confirm it.
Measure first. Then decide.
Sources
- PSA grading standards, for the quoted passage on subjectivity and the N8 miscut definition. Checked 10 August 2026. The numeric centering tolerances in the table above are hobby consensus, not quotes from this page.
- PSA trading card grading service levels and pricing. Checked 10 August 2026.
- Search query data is my own, from Google Search Console for coffeeandfun.com, 9 April 2025 to 8 August 2026.