Last summer I posted a draft of an improved formula for calculating business hours between two dates. It was meant to replace formula #13 on my formulas page, but I was waiting to do some additional real-world testing. Yesterday I got a good test case when a customer asked me to tweak the original formula to deal with start and end times outside the business day. I cleaned up a few typos and updated my formulas page.

This new version lets you separately specify a business start time and business end time for each of the 7 days of the week. It also includes additional logic to deal with events that start and/or end outside the business day (e.g. on a weekend, a holiday or after hours). The formula is now about 70 lines long. Fortunately, you only need to make changes in the first 20 lines or so. Here you specify:

• The DateTime fields to use for the Begin and End of each event
• The business start and end times assigned to each day of the week
• The list of holiday dates, which you can enter for multiple years

The output is a numeric value in hours as a decimal. If you want to show the value in “HH:MM” format you can use the “Elapsed Time String” formula on my site to convert this value into that format. Remember to multiply this formula’s result by 3600 since the input for the “Elapsed Time String” formula is seconds.

If you need help implementing this formula or any of my formulas you can always call to schedule a short consult.