I think the Post Office HAS an estimate of how long it will take things to travel from one zip code to another for each type of shipping, because if you go to their web site and look up shipping it gives the delivery time - but they don't make it available to merchants!! Only for outside the US. I hope they'll make it available to us at some point and then we could include it. Most times of the year, things take about 3 days in the US - but sometimes for no reason at all they take a couple of weeks! Fortunately this rarely happens.