As the world becomes more global, people are buying more products from other countries. Many of those purchases are from countries overseas in Europe, Asia or Australia. While the global economy and improved shipping has resulted in this possibility, shipping items from other countries is still more difficult than from within the United States. This issue is true within any country, but especially when it come to realistic shipping times when having to cross an ocean.
Customs always adds time to shipments which can vary from country to country, shipment to shipment and time of year. Customs randomly chooses packages to inspect more thoroughly although they do look for markers of illegal shipments. Specific categories of shipments may be due for extra inspections when they come under special scrutiny. Most packages clear customs within 24 hours, however some can take several days.
Shipping from overseas requires either a boat or plane to move the package. While shipping by air is clearly faster, even air shipments can take longer than within a country. Overnight air shipments are extremely costly between two countries. If you are ordering products from overseas, it is better to assume it will take at least two extra days than if you order within the U.S. If the product is shipped by boat, it can take one or more weeks because it is shipped on a pallet with other freight.
While the time difference when dealing with countries across the world does not add to the shipping time, it can add to the ordering or customer service time. Dealing with a country in a drastically different time zone makes it more difficult to reach people by phone, although email can cut through some of the delay. Ultimately, it just makes sense to add the different time factors in to your schedule when ordering from overseas.