What cards should i get graded has a short answer: the ones where certainty about condition is worth more than the submission costs. In practice that means scarce cards in sharp condition with an active market, and it is a small minority of almost any collection.
Scarce, because that is where condition pays
On a common card, a buyer who does not like the condition simply buys another copy, so certifying the condition adds little. On a scarce card there is no other copy this week, so the buyer is choosing between yours and waiting, and knowing exactly what they are getting is worth paying for. That is where the graded premium comes from.
Sharp, because the ladder is top-heavy
The price steps between grades are irregular and the largest steps are usually at the top. A card that will come back mid-ladder often gains little, and the fee is paid either way. Assess honestly, assume a grade below your instinct, and only send cards that still work at that assumption.
Actively traded, because a slab still needs a buyer
Grading does not create demand. A card with no recent sales in any form will have no recent sales in a slab either, and you will have added cost to an illiquid object. Check the sales record before the submission rather than after it.
Then check each candidate against the cost
Run the grading cost calculator once for the submission you are planning, take the cost per card, and run each candidate through the uplift calculator against it. Send the ones that come out positive at the conservative grade, and leave the rest raw.
Questions people ask about what cards should i get graded
Should I send my whole collection?
Almost certainly not. The fee is the same whatever the card turns out to be worth, so the cards that do not clear the hurdle simply cost you money.
What about sentimental cards?
Grading them is a preference and the calculators cannot answer it. They will tell you what it costs, which is the part that is arithmetic.
Is it worth grading a card I intend to keep?
The holder protects it and the grade records its condition. Whether that is worth the fee to you is not a question about value.
Do I need to grade to sell at a good price?
For most cards, no. For scarce, sharp cards in an active market, often yes, and the calculators show which is which.