7 min read · 6 April 2026
PSA centering requirements: the 55/45 rule, and how to measure yours
Centering is the easiest sub-grade to fail and the easiest to assess at home. It's also the only sub-grade where PSA publishes hard thresholds - so a deterministic measurement gets you a deterministic answer.
The thresholds
For the front of the card:
- PSA 10: max 55/45 on both axes.
- PSA 9: max 60/40.
- PSA 8: max 65/35.
- PSA 7: max 70/30.
- Worse than 70/30: PSA 6 or below.
Both axes - left/right and top/bottom - must meet the threshold. The worst axis is the ceiling. So a card that's 53/47 L/R but 64/36 T/B is capped at PSA 8.
How to measure manually
- Use a ruler with millimetre markings.
- Measure the inner artwork frame to each outer card border, on each axis.
- Compute the ratio:
min / (min + max) × 100.
Example: top margin 2.8mm, bottom margin 3.4mm → 2.8 / (2.8 + 3.4) × 100 = 45.2 (54.8 / 45.2). Just inside PSA 10.
How CPG measures it
We measure to 0.1mm using a deterministic geometric algorithm:
- Detect the outer card border via background-subtraction contour.
- Detect the inner artwork frame via Sobel-gradient edge detection.
- Compute four margins; output L/R and T/B ratios to one decimal place.
It's the same maths a sub-grader does with calipers - just faster, and without human eye-strain.
Front vs back centring
Most Pokemon cards have very consistent backs (the Pokemon back is machine-printed at high precision). The bigger variance is the front. PSA does measure both, but the back rarely drops the grade unless it's severely off.
What if your card is right at a boundary?
The closer to a boundary, the more grade variability you'll see across submissions. A 60/40 card will grade PSA 9 most of the time, but PSA 8 when a sub-grader is having a bad day. We reflect this in our verdict by lowering confidence near band boundaries.