Just use Pirate Ship. That's what I do anyway, better layout, actual customer service, and an insurance product that may just actually pay when needed. More on reddit.com

You're going to want more than 1" to properly pack it, and most likely the store quoted you a price to both pack and ship it. Unless the buyer is also paying for packing and shipping, it's unlikely that is a transaction worth doing. More on reddit.com

I've found the calculator to be very accurate (for both UPS and FedEx) IF you measure & weigh correctly. UPS was only added to eBay fairly recently and I've been auditing my shipments exactly to ensure no upcharge 'gotchas'. So far entirely accurate. By 'measuring correctly' I mean realize that 37.01" x 19.01" x 2.01" and 11.01 lbs should be entered as 38x20x3 @ 12 lbs. Similarly, be careful of 'irregular' sizes: if your package is 38x20 but one end is 3" high and the other is 2" high, that's 38x20x3 - you don't take the 'average' or anything. Another 'gotcha' is if you buy or get boxes with the 'size' printed on them, that's the INTERNAL dimensions. So if you take a box that says "12x12x12" and ship it using "12x12x12" as the dimensions, you're likely to get hit with an 'upcharge' for a 13x13x13 box... Also realize that the UPS charges the greater-of actual weight or 'dimensional' weight (based on size). So if a 0.1" or 0.1 lb difference you didn't include puts you from one into the other, charges can go up notably: basically you're jumping to a higher rate-tier. Also, if you ship a box that ends up bigger or heavier than UPS Ground actually handles, there's not just higher shipping fees, but a 'penalty' fee as well... So if you're mailing a box that's 149.9lb make DAMNED sure your scale is accurate, because if it's actually 150.1 lbs, you could face some SERIOUS upcharges. Given all the above, I've found IF you put in the truly-correct information, the calculated cost is very accurate. There do seem to be some legit horror-stories about folks getting whacked with completely overstated charges. But MOST of the ones I've seen where real info eventually got provided, it turned out to be mismeasurement and/or 'hoping to slide one by'... More on reddit.com

UPS stores are independently owned and operated franchises. They upcharge the shipping cost in order to make a profit. You can avoid this by making a UPS account and printing the shipping label yourself. As long as the box is fully sealed and labeled you can even still drop it off at the store and get a receipt. More on reddit.com