Lawyers, especially litigators, frequently need to calculate dates: a brief is due in 45 days, an appeal is due in 30 days, a contract or an order compels performance in 100 days, etc. I have been trying out some of the various date calculator apps for the iPhone for some time and I thought I would share my thoughts on three programs.
DaysFrom Date Calculator. This $0.99 app by Quinn McHenry of QD Ideas, LLC is my favorite of the bunch because it is simple and fast. At the top of the screen the reference date is listed -- by default, it is the current date, and you tap to change it. Listed below are the resulting dates that are a certain number of days in the future (or past). What I love about this app is that the user chooses the date ranges at the outset, and then they are set for as long as you keep them (although you can always add or remove the date ranges). Thus, once I set up the app just once for the date ranges that I use the most, subsequent uses of the app are very fast. Just pick the starting reference date and the ending dates are automatically listed.
This app does lack more advanced features, such as the ability to only count business days. Quinn tells me that he first developed this app for his wife, a pharmacist who often needs to know what is 100 days in the future, and that while he has considered adding more advanced features such as excluding weekends, holidays, etc., he found that it just added too much complexity to the app. Frankly, I think that Quinn made the right call. Simplicity is a virtue, and being straightforward and quick is what makes this app great. And priced at only a buck, I can't imagine anyone being disappointed with this app.
DateCalcPro. This $2.99 app from Adam Alexander has a few more features than DaysFrom. When you launch the app, the default start date is whatever date you used last in the app and the default calculation period is whatever you set the last time you used the app, which some might find to be a useful feature. You can count either a number of days, weeks, months, and/or years in the future or the past. You can also pick two dates and the app can tell you the number of days between those dates (or even the years, months, weeks and/or days between the dates). By default, the app counts every day, but you can also tell the app which days of the week to count, such as only Monday through Friday. That feature could be useful if you are in federal court and confronting a deadline of less than 11 days for which, pursuant to Fed. R. Civ. Pro. 6, you don't weekends or holidays; the app won't take into account holidays, but the app can handle the weekends for you. Frankly, for those 10 days or less periods I can just do the math in my head, but I can see this feature being very useful if you need to count business days for a longer period of time.
This app works well, and the author even has a Google Groups forum where you can discuss the app and request more features. The only reason that it not my favorite of the apps is that it is just a little too powerful for my needs. Because of all of the options, I find myself having to adjust several settings to get what I want, and DaysFrom just works faster for me with fewer taps. But if you have the need for more sophisticated date calculations, you will like this app.
Date Calc. This $4.99 app from Morgan Brown Consultancy, Ltd. is the most ambitious app of this group. It allows you to not only count calendar days and business days, it also allows you to choose from one of 16 different holiday calendars. The U.S. calendar, for example knows about 10 holidays: New Year's Day, MLK's Birthday, Washington's Birthday, Memorial Day, Independence Day, Labor Day, Columbus Day, Veteran's Day, Thanksgiving Day and Christmas. (Yes, that list complies with Fed. R. Civ. Pro. 6(a)(4)(A).) You have an option to either go to today when you launch the app or go to the last date that you entered. Like DateCalcPro, you can either pick one date and then count forward (or backward), or you can pick two dates and determine the number of days between them. The app even allows you to send your results via e-mail. So in terms of sheer number of features, Date Calc has the most.
As you can see, the interface of this app is unique and does not comply with the normal iPhone user interface (UI) standards. In one sense this is a plus; it is nice to see a calendar. On the other hand, the UI takes some time to get used to and the buttons are small and non-standard. Please be aware that there is one very important aspect of Date Calc that you must consider when using the app -- currently, the app begins counting on the first date of a range. Thus, if your starting date is April 1 and you want the app to count forward 5 days, the app will tell you that the last day is April 5th, not April 6th. In other words, the app does not comply with Fed. R. Civ. Pro. 6(a)(1), nor the rules of most states, which tell you not to count the day that begins the period. (In Louisiana, for example, see La. C.C.P. art. 5059.) However, the author of the app, David Morgan-Brown, tells me that this will be addressed in an update to the app that should be released in May. He also plans to add the ability to save common offset calculations (15 days, 30 days, etc.) and larger fonts, which he tells me are two other features frequently requested by lawyers. Those additions would greatly improve this sophisticated app.
For me, the UI is a negative, but I realize that is purely a personal preference. Fortunately, the developer has made it easy for you to decide for yourself whether you like the UI becasue there is a free version of this app called Date Calc Free. This version only tells you the number of days between two dates that you select; you can't pick one date and then have the app count a specific number of days in the future. The free version also lacks the holiday calendars. Nevertheless, if you are thinking of getting the full version of Date Calc, I encourage you to first try the free version just to get a sense of whether you like the interface.
Conclusion. These three apps take different approaches to calculating dates. All of them do the basic job of counting forward (or backwards) a number of days, and which you pick is really just a matter of personal taste on factors such as the interface and simplicity versus features. DaysFrom is my favorite of the bunch because of the simplicity, but DateCalcPro is fantastic for its advanced features. Date Calc seems less useful for litigators right now because of the way it counts, but once updated in May, I suspect that some people will consider it the best because of all of the advanced features. It is nice to have choices, and I would be interested to hear from you on which one you like the best.
Click here to get DaysFrom ($0.99): 
Click here to get DateCalcPro ($2.99):
Click here to get Date Calc ($4.99):
Click here to get Date Calc Free (free):
