Why and how does Project calculate duration in decimal amounts?

[groggydoggie]

In the duration column of Microsoft Project some days are shown as fractional
amounts with decimals. Why and how does it do this? For example, why doesn't
it show 3 days instead of 2.75. These fractional numbers seem to be only on
parent, or summary tasks. Do I have to change my settings for the summary
tasks in order to get them to be whole numbers?

 

[John]

In the duration column of Microsoft Project some days are shown as fractional
amounts with decimals. Why and how does it do this? For example, why doesn't
it show 3 days instead of 2.75. These fractional numbers seem to be only on
parent, or summary tasks. Do I have to change my settings for the summary
tasks in order to get them to be whole numbers?

groggydoggie,
If any task starts or ends at a time that is different from the work day
Start and Finish times (i.e. default 8:00 am and 5:00 pm), the Duration
of that task will show fractional days. This is also true of Summary
Lines whose Duration is calculated by Project to be the number of
working days (default) from the Start of the first subtask to the Finish
of the last subtask under it.

"Off-hour" Start and Finish times can result from many different things
including, but not limited to, resource assignments, leveling, user
input, etc.

There are basically two ways to ensure Duration is in whole days. First,
make sure all tasks only Start and Finish at the default times, or, set
up a custom field with a formula that rounds the Duration to whole days.

Hope this helps.
John
Project MVP

 

[Jan De Messemaeker]

Hi,

Maybe you should also read
http://www.mvps.org/project/faqs.htm
Faq5: Default working hours
That is the most common reason for decimal durations.
HTH

 

[Nwazue N.]

In the duration column of Microsoft Project some days are shown as fractional
amounts with decimals. Why and how does it do this? For example, why doesn't
it show 3 days instead of 2.75. These fractional numbers seem to be only on
parent, or summary tasks. Do I have to change my settings for the summary
tasks in order to get them to be whole numbers?

Greeting everyone, having similar issue. Tried to change the settings to fixed duration from the options (shedulling - default task type - then fixed duration). Then i double click on the duration which i would wanna edit to a whole number, click on general and change to manually shedule, den go to custome fiels to edit. It actually worked but my major challenge is that it changes the Actual finish date. Really need help on this one