I do a fair amount of billable hour work in my practice. Over the years, I've developed a fairly simple but flexible spreadsheet for tracking my billable time. For our firm, this represents the ideal solution at present. I have taken a liking to a few different Mac billing apps out there (like Billings, Involer, Invoice, GrandTotal, and iRatchet) but each of them falls short in one way or another for our purposes. I would encourage you to give them a try, however, as your needs might be different than ours.
Early on, I would write my time down here and there, and at the end of the month, I would be gathering my snippets of billing information from all over my office and my computer - even going back over my recent emails and documents to forensically reconstruct my billable time for the month. As you can imagine, you lose a fair amount of billable time that way - both for time it takes to recreate the month, and for the work that ultimately never gets billed for because it was missed in the reconstruction.
Obviously, I needed to find a system for capturing my time contemporaneously with the work I was billing for. For a while, my solution was to keep a legal pad next to my computer and jot down my work as I was doing it. That's not a terrible solution, but it left me at the end of the month with a good bit of work still to do. I would go over the pages of chicken scratch (yes, surprise, my handwriting is horrific), and try to give a client-by-client report to our secretary who creates and sends out our billing invoices.
Eventually, I realized that by using a spreadsheet, I could capture my time as I do the work, and, at the end of the month, we can manipulate the data in any way we want. Specifically, the data can be arranged by client or matter to give our billing secretary easy access to copy and paste the relevant information.
As most firms do, our firm bills by the tenth of an hour.
It is easy to type in the start time and end time for your tasks in the spreadsheet. The hard(er) part is to do math with the time, convert it to tenths and round it up to the next tenth. Of course, this can be done manually, which is how I used to do it, but the with power of Numbers and Excel, it can easily be done automatically - if you know the right formulas.
First, you need to make sure your start and end time columns are set to the Date and Time format. The next step is intuitive enough: subtract the start time from the end time. If that is all you do, however, your result will be something like "0.0" because the spreadsheet doesn't fully understand what you're up to. Multiplying the whole answer by 24 will give you a decimal representation of the time. But, you're not done yet. At this point, you may get an answer like 0.717. You could just set the decimal places to 1 in the cell format settings, but that would round to the nearest tenth, rather than rounding up. The solution is to add the ROUNDUP operator to the beginning of the formula. To tell the spreadsheet what decimal place to round up to, add a ",1" to the end of the formula.
In the end, your formula for calculating time to the tenth of an hour, rounding up, is "=ROUNDUP((B1-A1)*24,1)" where B1 is your end time and A1 is your start time.
So, without further ado, here are two templates for tracking your billable time:
One final tip: I have found that in order for me to practically capture my time as I do the work, I need to have the spreadsheet very quickly accessible. The way I accomplished this was to put the billing document in my dock. Just drag the document from where ever you keep it to the right side of the dock (where your "stacks" folders are kept), and it will stay in the dock for one click access to your timesheet.