The honest answer is that a pair of sneakers has no single value — it has a value in a size, in a condition, with or without its box.
What actually moves the number
Size. The same shoe in a common size and a rare one are different items. This is the single biggest surprise for people selling their first pair.
Condition. Deadstock, worn twice, worn. Three objects, three prices.
Completeness. Original box, extra laces, inserts. For a deadstock pair the box is part of what is being bought, and a crushed one costs real money.
Colourway and release. A general release and a limited one are not the same shoe even when the silhouette is identical.
Why two of the same fetch different money
Because one seller showed the size tag, the sole, the toe box and the heel, and the other showed three photographs from above. A buyer who cannot see wear assumes more of it than there is. Why naming the flaw raises the price.
How to find out rather than guess
Look at completed sales, not asking prices — what somebody listed a pair at tells you what they hoped for.
Match on the specifics: same size, same condition language, same box situation. A comparable that differs on size is not a comparable.
Then accept that the number is a range, not a figure.
The live answer
A pair shown properly in a room full of people who want that size is priced in about ninety seconds, and that price is real in a way no estimate is. If you are unsure, start low and let the room tell you. How auctions find a price.
Questions people ask
Does cleaning them raise the value?
A careful clean helps. Anything aggressive damages materials and shows, so describe rather than restore.
Are my old everyday trainers worth selling?
Often as part of a lot rather than alone. Common pairs in worn condition sell quickly at honest prices.
What if I have no box?
Say so plainly. It lowers the price on a deadstock pair and barely matters on a worn one.