By Allen Wyatt for Excel.Tips.Net
Peter asked if it was possible in Excel to create a custom number format that will deal with imperial linear distances, such as inches, feet, miles, etc. The short answer is that no, this is not possible. Excel works natively in the decimal system, and many imperial measuring systems are based on other numeric systems (feet on base 12, for instance). While custom formatting can change the way that numbers are displayed, it cannot perform the conversions necessary for imperial measurements.
Your best bet is to keep the different units of whatever imperial measurement you want in different cells. For instance, a distance of 3 miles, 428 feet, and 7 inches could be kept in three cells, one for miles, one for feet, and the other for inches. You could then write the formulas necessary to convert to whatever measurement system you desire. There are also Excel add-ins available around the Internet (a quick search will find them) that can allow you to use this technique to work with linear measurements.
This post is excerpted with permission from Excel.Tips.Net