# Workday Formula Fridays

I am currently using a workday formula to calculate an end date based on a “Start Date and an
Average Length of Completion” for a task. My issue is with single-day tasks, if the task begins on any day other than a Friday, the formula works. If it starts on a Friday, it won’t calculate as a single day.

Formula is: DATEADD(WORKDAY({Start date}, {Length of Days}), -1, ‘days’)

tl;dr: Monday-Thursday formula works and returns the correct end date. Friday start date calculate a Monday end date.

Hi @James_Masciovecchio
My apologies, can you explain the purpose of the -1 in your formula?

Removing it from the formula. I set a date of 5/27/2022 with a Length of Days set to 1 and the formula returns Monday 5/30/2022.

So Airtable generally returns a 1 day length as a full 24 hours. So your Start Date would go 5/25 to 5/26. However that is not accurate as the event is same day, starting and ending on the 25th. You put the “-1” in to account for that. It’s how the system accounts for the start date as 1 day,

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