Calculate expected percentage

Hi,

I have the following date of where my progress should be by these dates:

Start: 01/08/2017:
25% complete: 02/09/2017
50% complete: 10/10/2017
75% complete: 12/12/2017
End: 31/12/2017

I want to work out what % i should be on, based on todays date.

As the amount of dates are not the same between each quarter i have been unable to work this out.

Any help would be greatly appreciated.

Should every day from October 10th 2017 to December 11th 2017, for example, return 50% complete?

No, for example on the 12th October it would show 52% (or whatever % would be correct)

That's tricky. Try this (see attachment)

I created a lookup table which includes the completion %, the date, and the number of days in each range.

I then used the following formula
=SUM(LOOKUP(E2,B2:B6,A2:A6),(0.25*(E2-MAX(IF(B2:B6<=E2,B2:B6)))/LOOKUP(E2,B2:B5,C2:C5))) Ctrl Shift Enter

Hi,

Thanks for your help!

When I choose today's date, the percentage is shown as -96%. Any ideas?