Calculating precise number of months between two specific dates

Adetro

New Member
Joined
Feb 18, 2021
Messages
7
Office Version
  1. 2016
Platform
  1. Windows
Hello. I'd really like some help with this. I really appreciate any replies.

I need to do forecasting on salary costs for staff members. They are paid a salary which is divided equally between the months. So if their salary is £36,000, then they get paid £3,000 in February, and £3,000 in March, and £3,000 in every month of the year.

I have been trying to tweak the below formulae which I've found in a thread from 2012. Both formula does the same thing. However, currently those formulae assume that the start date is to be discounted from the answer, but I need it to be inclusive.

=(DAY(EOMONTH(A1,0))-DAY(A1))/DAY(EOMONTH(A1,0))+DATEDIF(A1,B1,"m")-1+DAY(B1)/DAY(EOMONTH(B1,0))

=DATEDIF(A2,B2,"m")+DAY(B2)/DAY(EOMONTH(B2,0))-DAY(A2)/DAY(EOMONTH(A2,0))

Thus, someone will work for us as follows:
Start date: 01/07/2021 (or 07/01/2021 in US terminology)
End date: 31/12/2021
This is exactly 6.0 months. But using the above formulae I get 5.96774 months, because it's subtracting 1st July.

What I need is the precise formula which would also include 1st July in the months counted.

But it also needs to work if someone is commencing or departing at any point in a month, not necessarily just the start/end of a month

Many thanks in advance
Paul
 

Some videos you may like

Excel Facts

Get help while writing formula
Click the italics "fx" icon to the left of the formula bar to open the Functions Arguments dialog. Help is displayed for each argument.

Candyman8019

Board Regular
Joined
Dec 2, 2020
Messages
138
Office Version
  1. 365
Platform
  1. Windows
You could try something along this line substituting the dates for your specific cell:
=MONTH(DATE(2021,7,1)-DATE(2021,1,7))
 

mart37

Well-known Member
Joined
Aug 4, 2017
Messages
1,044
Office Version
  1. 2016
Platform
  1. Windows
=DATEDIF(DATE(YEAR(A1),MONTH(A1),1),DATE(YEAR(B1),MONTH(B1),DAY(EOMONTH(B1,0)))+1,"m")
 

Fluff

MrExcel MVP, Moderator
Joined
Jun 12, 2014
Messages
55,251
Office Version
  1. 365
Platform
  1. Windows
Hi & welcome to MrExcel.
Maybe
Excel Formula:
=DATEDIF(A2,B2,"m")+DAY(B2)/DAY(EOMONTH(B2,0))-(DAY(A2)-1)/DAY(EOMONTH(A2,0))
 

Adetro

New Member
Joined
Feb 18, 2021
Messages
7
Office Version
  1. 2016
Platform
  1. Windows

ADVERTISEMENT

=DATEDIF(DATE(YEAR(A1),MONTH(A1),1),DATE(YEAR(B1),MONTH(B1),DAY(EOMONTH(B1,0)))+1,"m")
Thank you for your reply. Unfortunately this only gives a whole number of months. If the start date is, say, 11th June, and the end date is the end of a month, then I'll want the answer to show .667
 

Adetro

New Member
Joined
Feb 18, 2021
Messages
7
Office Version
  1. 2016
Platform
  1. Windows
=DATEDIF(A2,B2,"m")+DAY(B2)/DAY(EOMONTH(B2,0))-(DAY(A2)-1)/DAY(EOMONTH(A2,0))
Thank you for your reply.

Unfortunately, if I enter a start date of 09/12/2020, and an end date of 05/01/2021, the formula gives an answer of -0.0968.
 

Fluff

MrExcel MVP, Moderator
Joined
Jun 12, 2014
Messages
55,251
Office Version
  1. 365
Platform
  1. Windows

ADVERTISEMENT

In that case can you please post some sample data showing expected results.

MrExcel has a tool called “XL2BB” that lets you post samples of your data that will allow us to copy/paste it to our Excel spreadsheets, so we can work with the same copy of data that you are. Instructions on using this tool can be found here: XL2BB Add-in

Note that there is also a "Test Here” forum on this board. This is a place where you can test using this tool (or any other posting techniques that you want to test) before trying to use those tools in your actual posts.
 

Fluff

MrExcel MVP, Moderator
Joined
Jun 12, 2014
Messages
55,251
Office Version
  1. 365
Platform
  1. Windows
Maybe
Excel Formula:
=YEARFRAC(A2,B2)*12
Failing that I will need examples
 

Adetro

New Member
Joined
Feb 18, 2021
Messages
7
Office Version
  1. 2016
Platform
  1. Windows
In that case can you please post some sample data showing expected results.

MrExcel has a tool called “XL2BB” that lets you post samples of your data that will allow us to copy/paste it to our Excel spreadsheets, so we can work with the same copy of data that you are. Instructions on using this tool can be found here: XL2BB Add-in

Note that there is also a "Test Here” forum on this board. This is a place where you can test using this tool (or any other posting techniques that you want to test) before trying to use those tools in your actual posts.
Thanks, Fluff, for getting back so swiftly.

Essentially, every whole month between the two dates should count as 1.0, and the two months which are included in the specified dates should be >0.0-1.0, depending how much of the month is covered. I give some examples of this below.

01/01/2021​
31/12/2021​
12​
18/02/2021​
25/07/2021​
5.1993088​
19/02/2021​
15/09/2021​
5.8571429​
20/02/2021​
15/09/2021​
5.8214286​
21/02/2021​
27/11/2021​
9.1857143​
22/02/2021​
28/11/2021​
9.1833333​
23/02/2021​
29/11/2021​
9.1809524​
24/02/2021​
03/09/2025​
53.278571​
25/02/2021​
03/09/2025​
53.242857​
26/02/2021​
04/09/2025​
53.240476​
27/02/2021​
25/02/2025​
46.964286​
28/02/2021​
17/01/2022​
9.5841014​

Essentially, what I have done here is use the formula I posted in my OP, but included a second column (hidden above) which simply subtracts one day from the first column. This means that the forumla now works, but I would really like this to work without having to add an additional column.

Sorry, I'll have to see if I can upload this as a spreadsheet! Many thanks again!
 

Watch MrExcel Video

Forum statistics

Threads
1,126,982
Messages
5,621,964
Members
415,869
Latest member
LWSkinner

We've detected that you are using an adblocker.

We have a great community of people providing Excel help here, but the hosting costs are enormous. You can help keep this site running by allowing ads on MrExcel.com.
Allow Ads at MrExcel

Which adblocker are you using?

Disable AdBlock

Follow these easy steps to disable AdBlock

1)Click on the icon in the browser’s toolbar.
2)Click on the icon in the browser’s toolbar.
2)Click on the "Pause on this site" option.
Go back

Disable AdBlock Plus

Follow these easy steps to disable AdBlock Plus

1)Click on the icon in the browser’s toolbar.
2)Click on the toggle to disable it for "mrexcel.com".
Go back

Disable uBlock Origin

Follow these easy steps to disable uBlock Origin

1)Click on the icon in the browser’s toolbar.
2)Click on the "Power" button.
3)Click on the "Refresh" button.
Go back

Disable uBlock

Follow these easy steps to disable uBlock

1)Click on the icon in the browser’s toolbar.
2)Click on the "Power" button.
3)Click on the "Refresh" button.
Go back
Top