Card Centering Calculator: Border Ratio to Max PSA Grade

Centering is the one part of a card's condition you can put a number on before submitting it. PSA's glossary calls it one of the most important factors in determining a card's grade and says it is found by measuring the distance between the photo and the edge of the card from opposite sides. PSA's grade definitions then put a ceiling on each grade: a card can have perfect corners and still fall short of a 10 because one border is too wide.

Centering checkany unit · same unit on all four sides

Centering allows up to––

–

Centering only: corners, edges, surface and print quality can still hold the card below this ceiling, and PSA describes its limits as approximate.

How the calculation works

For each pair of opposite borders, the calculator divides the wider border by the total of the two and writes the result the way graders do, as a pair of percentages that add to 100:

PSA's own glossary example is a card that is 50/50 top to bottom and 60/40 left to right — shifted left, with 60% of the horizontal border on the left of the photo and 40% on the right. In the calculator's default example, borders of 2.0 and 3.0 give 3.0 ÷ 5.0 = 60%, so 60/40, which is the MINT 9 limit on the front.

PSA's centering limits by grade

Maximum off-center ratio allowed for an unqualified grade, from PSA's published grade definitions
Grade	Front	Back	Larger border ÷ smaller (front)
GEM-MT 10	~55/45	75/25	1.22
MINT 9	~60/40	90/10	1.50
NM-MT 8	~65/35	90/10	1.86
NM 7	~70/30	90/10	2.33
EX-MT 6	80/20	90/10	4.00
EX 5	85/15	90/10	5.67
VG-EX 4	85/15	90/10	5.67
VG 3	90/10	90/10	9.00
GOOD 2	90/10	90/10	9.00
FR 1.5	~90/10	~90/10	9.00
PR 1	—	—	No centering limit stated

The last column is simple arithmetic on PSA's ratios and is handy at a card show: if the wider border on the front is more than one and a half times the narrower one, the card is past the MINT 9 limit; more than about 1.22 times and it is past the GEM-MT 10 limit. A tilde marks limits PSA describes as approximate.

Reading the result

It is a ceiling, not a prediction. PSA grades corners, edges, surface, focus and eye appeal as well. The calculator only tells you which grades the centering rules out.
The back counts, but less. Every grade from 2 to 9 allows 90/10 on the reverse; only a 10 asks for 75/25 or better.
Graders keep some discretion. PSA's standards page says a small variance may be permitted on occasion based on a card's overall eye appeal — and gives the example of a card that technically measures 70/30 but may be kept from that unqualified grade if the market would see it as off-center.
Half grades lean on centering. PSA's definitions allow a half-point increase for high-end cards between PSA 2 and PSA 9, with a clear focus on centering.

Off-center cards and the OC qualifier

A card that misses the centering limit does not always drop to a lower number. PSA defines a qualified card as one that meets all the criteria for a grade but fails the standard in one area. Its example: a card with all the qualities of NM-MT 8 but 90/10 centered left to right receives NM-MT 8 OC, where OC stands for off-center. PSA's glossary gives a second example: a card that meets the standard for MINT 9 but is 65/35 would be designated MINT 9 OC. The PSA grading scale guide lists the other qualifiers.

Measuring tips

Measure from the edge of the card to the edge of the printed image or frame on each side, as PSA's glossary describes — the same reference line on opposite sides.
Use one unit for all four borders. A flat, straight-on scan measured in pixels works as well as a ruler, because only the proportion matters.
Check both axes. A card can be perfect left to right and still miss a grade on top-to-bottom centering; the calculator uses the worse of the two.
Measure the back too if you are hoping for a 10.

Card centering calculator

Front

Back optional