Consider
Greninja (XY) sits in borderline territory for grading. Raw copies trade around $11.88 while PSA 10s sell for about $136.23, a 34% Return on Grading. Only send it if you're confident the copy is a genuine Gem Mint candidate.
Most grading maths asks you to guess your odds of a PSA 10 first. This works backwards from the prices instead and tells you what those odds would have to be.
The number is different on every card. It's how confident you'd need to be that this copy gems before grading pays for itself, so 20% means roughly a 1 in 5 shot and 50% means a coin flip.
Grade it if you rate your copy better than that, leave it raw if you don't.
It assumes a 9 is the worst you'll get. Centering and edge whitening send plenty of modern cards back at 8 or lower, and that's not priced in here, so treat this as the floor of the bar rather than the whole of it. Selling fees aren't counted either.
(cost - PSA 9) ÷ (PSA 10 - PSA 9)
Pays off even at PSA 9
A PSA 9 alone ($106.03) already covers your $101.88 cost (raw + grading + shipping), so you don't need the 10 to come out ahead.
Anything from a 9 upwards puts you ahead, and a 10 would net you $34.35. The only real risk left is the card grading below a 9.
Among the 30 cards in XY with PSA 10 sale data, Greninja ranks 12th for Return on Grading and 13th by PSA 10 price. Of the 15 Rare Holo cards with PSA 10 sales, it is 3rd for Return on Grading. The median PSA 10 in this set sells for $110.84. 9 of the 30 clear a 100% Return on Grading.
