Shipping estimates for many online sellers come from realms in which the customary rules of math do not apply. Not only do ends of business days and weekends tack on time to shipping estimates, but additional bonus days tend to pop in as well.

Take ournextcontestant’s experience in trying to get Target to ship out a Wii in a timely manner:

Buying a Wii for my soon-to-be 8-year-old nephew on Target.com. On the website on Tuesday evening (Oct. 19). Birthday is Sunday, so regular shipping is dicey. I opt for two-day shipping and, luckily, just before completing the order, I see the estimated arrival date is Oct. 25. Hmmm, that’s six days. But even allowing for placing the order in evening and losing a day, Oct. 20 to Oct. 25 is, of course, not two days (not even two business days). Just for kicks, I change the shipping to one day, and it comes up Oct. 22.

So, to review: One-day shipping is not one day, two-day shipping is not two days, and one-day shipping gets there three days quicker than two-day shipping.

In the end, I opted for one-day shipping, as it was just two dollars more.

The shipping estimate, of course, refers to the time it takes the item to get to you once it’s actually sent out, which seems to vary depending on when the shipper gets around to sending your package.

What’s the most you’ve paid to expedite the shipment of something you bought online?

Want more consumer news? Visit our parent organization, Consumer Reports, for the latest on scams, recalls, and other consumer issues.