Dear Alexandre , moutaz
I hope im correct about what ill explain well here what i understood
MS project is having around 4 calenders
base calender and project calender and tast calender and resource calender too
so what im interested in here is the the MS proj software have its defult values like this:
the base calender is 8 hours per day and 5 days per week and the starting hour of work is 8:00am and ending at 5:00pm with one hour break
ok this is his base if you start a new project MS proj is asking you some things like :
when is the project will start and if i want to save my project on server or not and this is the first step in the project guide the critical one is the next step
in the project guide which is called : Define general working time and here you setup the project calender
now everybody must take care of something if u defined your working time differently than the program defults
which is 8:00 till 5:00 and 8 hours per day and 5 working days per week for sure it will appear those fractions in the duration
cause the program will take what u entered measure it or divide it according to its defult and give u in fraction the deviation between what he have and what you entered
i can give numerical example for this:
lets start with MS project and start new project:
leave everything as default in the MS proj if not modify them
so before to start the new project go to :
Tools menue: and select :Options
and then go to calender and select or modify the defaults of the program by entering 8:00 am and 5:00 pm in both default starting and default ending time for a working day
and then move to hours per day enter 8
and then move to hours per week enter 40
and put days per month = 20 so now PRESS THE BUTTON "Set as Default"

now you are sure that the program is having its original Defaults
now go to make new project and even if you have different values for working like 10 hours or something else dont bother ur head now
then go to define the project and enter the starting day of the project enter any day you want lets say 1st of march this year
now now move to the next step
which is server one click now and then finsih this step
NOW GO to define general working times step and as i think this is the project calender which will be the tast calender if u didnt specify any calender to a task
lets think this way that my project working time will be
10 hours and 6 working days and start from 8:00am till 7:00pm
with one hour break for lunch
ok so he ask u now to select calender template
well leave it as standard cause its just a template u r using to identify your project calender
ok and move to the next step

the program ask u now "Which days of the week are the usual work days for this project? "we select all of them except sunday cause we want 6 days per week
and now choose the other choice which is "I want to adjust the working hours shown for one or more days of the week "
and move to another step

enter the new working time change only 5:00 pm till 7:00 pm to have in you project calender 10 working hours and leave the one hour break for lunch and press apply for all days button
then press save and go to step 3 link
skip the step for entering holidays and vacations and so on and move to another step
take care now the program is giving u his default which is
8 hours
40 hours
and 20 days
now change those to be like this
10
60
26
and start to enter activity A and activity B and activity c
and lets assume that A will start on 3/2/07 and end of 3/5/07 on the calender u will find out that those r 3 days from friday 2nd of march and saturday 3rd of march
and monday 5th of march but the duration will not be 3 will be 2.8 so u r working now everyday 10 hours this mean ur project calender is faster than the base calender
which is for MS project default 8 and 40 and 20
so what happened is the program saw that the first 2 days u finished 20 hours working from an activity which needs 3 days working on his calender so the last day will be 8/10 = 80%
so this activity with ur rate of working will not finished more fast or more earlier than the calender states it will finish in 2.8 days not 3

what to do if u wanna avoide this ok u must make a task calender and let the base calender or the MS project and the project calender are identical
so close the program open it again and before to start anything go to tools options and in calender tab change everything to default 8 40 and 20 and press set as default

press new project and go thru the same steps dont modify anything leave everything as default and eneter again A B and C with the same dates
u see he give u 3 days 2 days and 2 days without fractions
now suppose u want activity A to have this scheme which is 10 hours 6 days go to make calender and assign this calender to that activity
go to tools and now this time go or press change working time and press in this tab the button new
now u wanna make a task calender
name it like 6 h 10 days calendar
and choose the second option make a copy of standard calender
and now edit ur working hours and select all saturday in the calendar and edit the working hours for them to be from 8 till 7 with one hour break and press Ok
now u can go for activiy b or d and double click it and then u will specify in advanced tab the new calender u want for this activity
and u will not see 1.8 day u will see 2 days but estimated duration 2 days?
anyway i think when we plan we enter the duration and let the program to tell me the finish date
its very rarely to enter the start and the finish date and the program tell me the duration
cause when u plan u know every precess and how much it can take
i hope i was correct about what i explained
thanks.........

we have the same prob and i think in MS project we have two or 3 kind of calenders and i started to change the data in the options calenders and i started to change the hours per day and i put it once 8 and once 10 and once 24 while my original setting at starting the project was 10 hours per day for working including saturday and this mean 6 days per week and 60 hours per week and after i started to enter the activities he started to give me something like 1.8 one day and 80% of a day which mean i guess that the program took the next day as his default working hours as 8 and he divided 8/10 cause when i go to tool menu and options and calender and i started to change or to play with the values in working hours per day like this 24 he gave me 0.75 day which mean one day which mean i guess or according to my understanding he took 20 divided by 24 and it was 75% i really dont know for sure if somebody can explain to us or help us cause im new commer in this and this is my first action with MS project thanksss....