Is 60/40 centering good? Card centering ratios explained

What do 50/50, 55/45 and 60/40 actually describe?

The first number is the larger share of an opposing-border pair and the second is the smaller share. They sum to 100. A 50/50 pair has equal widths, a 55/45 pair has a modest imbalance and a 60/40 pair is more displaced. They describe relative balance, not absolute thickness, card authenticity or surface condition.

The ratio alone also loses direction. A left border of 3.60 mm and right border of 2.40 mm is 60/40; swapping them gives the same imbalance with the print displaced in the opposite direction. Keep named left, right, top and bottom measurements if direction matters. Left/right and top/bottom are two separate ratios, not four shares of one total.

Two cards can share the same ratio with very different border widths. A pair of 1.80 and 1.20 mm has the same 60/40 balance as 3.60 and 2.40 mm. A small absolute reading error has more influence on the narrower pair, which is why a single ratio without uncertainty can overstate confidence.

How is a centering ratio calculated?

Call the opposite border widths A and B. Calculate the wider share as max(A, B) ÷ (A + B) × 100, then subtract it from 100 for the other share. Both widths must use the same units and corresponding positions along the printed frame. Use rectified pixels or millimetres; do not mix them in one pair.

Worked example: left 3.30 mm, right 2.70 mm. Their sum is 6.00 mm. The larger share is 3.30 ÷ 6.00 × 100 = 55%, so the horizontal ratio is 55/45. If top is 3.90 mm and bottom is 2.10 mm, the vertical ratio is 65/35. The PSA front ceiling is then 8 NM-MT, because the vertical pair limits the front.

Do not divide 3.30 mm by the whole 63 mm card width: that gives a border's share of the card, not centering. Do not average the two axis ratios into a single favourable value. The measurement guide explains how to establish valid boundaries before doing the arithmetic.

Which front ceilings correspond to ratios from 50/50 to 90/10?

The following table deliberately assumes both axes have the stated ratio. That makes it reproducible, but it is a specific scenario rather than a result for every card with that worst ratio. Values come from the grading model, and missing intermediate bands remain missing.

Front only, both axes at the stated ratio. BGS can have a higher ceiling if the other axis is better; the two-axis table below shows that difference. CGC has missing intermediate bands. SGC is approximate, lower BGS bands are approximate; other non-official rows are interpreted. Read the full standards before treating any number as a rule.

A low model ceiling is not a declaration that the card should be discarded or cannot be collected. It tells you that the measured geometry is outside a higher centering band in this reference. For worn cards, the surface or corners may become the stronger constraint anyway. The grading checklist puts the ratio in context without assuming a sale price or final grade.

Why does BGS need both axis ratios?

Some BGS front bands specify one looser limit and one tighter limit. Compare the worse axis with the former and the better axis with the latter. With a 60/40 axis, changing the other from 60/40 to 55/45 changes the model ceiling from 8 NM-Mint to 8.5 NM-Mint+. An answer based only on “my card is 60/40” cannot resolve that distinction.

This is Centering Lab's interpretation, not a guarantee of a BGS subgrade or final grade. L/R and T/B can be swapped without changing the result.

Keep interpretation and approximation visible when quoting BGS results. These bands are not newly verified official promises. The house comparison explains the sources and why a centering calculation cannot determine an overall BGS grade.

What do these ratios mean in millimetres on a 63 × 88 mm card?

There is no fixed millimetre conversion from a ratio without the border sum. Assume a 63 mm-wide card with a 57 mm-wide printed frame: the two horizontal margins total 6 mm. At 60/40 they become 3.60 and 2.40 mm. The frame's horizontal displacement from perfect balance is half their difference, (3.60 − 2.40) ÷ 2 = 0.60 mm, rather than 1.20 mm.

6 mm is a hypothetical border sum, not a standard for any card. On a 63 × 88 mm card a 57 mm-wide printed frame leaves 6 mm horizontally. The vertical sum depends on the frame height and must be measured separately.

The 88 mm height does not imply the same vertical border sum. If the printed frame is 80 mm tall, the vertical sum is 8 mm. A 60/40 vertical pair would then be 4.80 and 3.20 mm, with a 0.80 mm offset. These frame dimensions are hypothetical examples, not measurements of a particular set. Nominal dimensions and format selection affect the millimetre scale, while the ratio remains based on the opposing widths.

How should rounding and uncertainty affect the result?

Centering Lab displays whole-number ratios and uses a half-point comparison convention in its model: the unrounded major share must stay strictly below the listed threshold plus 0.5. For the PSA front top band, a hypothetical 55.49% reading stays inside that model comparison, while 55.50% does not. This is software behaviour, not an extra allowance promised by PSA.

Retain the raw value near a boundary and look at uncertainty. A reading of 55% with plausible error of ±1 percentage point can fall on either side. Repeat the photo, inspect the cut and print lines and state that the result is borderline if the plausible range crosses the boundary. Cropping, sharpening or repeatedly adjusting a line until the displayed ratio passes does not improve the evidence. See the method for how the checker reports measurement uncertainty.

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