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Ansh P., MS Office Specialist
Category: Microsoft Office
Satisfied Customers: 8147
Experience:  Computer Science Engineer with 10 years experience in MS Office (All Versions).
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# help me. please! how can i calculate the date of birth if i

### Resolved Question:

help me. please! how can i calculate the date of birth if i know a person's age at march 31, 2013. e.g. a person was 39.05 years old on march 31, 2013. what was their date of birth if A1 is 39.05 years old? what is the formula i should use? please.

Submitted: 2 years ago.
Category: Microsoft Office
Expert:  Ansh P. replied 2 years ago.

JATechSpecialis :

JATechSpecialis :

Are you using Excel 2007 or 2010 version?

Customer:

i believe it is 2010

Customer:

sorry. itis 2007

JATechSpecialis :

JATechSpecialis :

=(TODAY()-A1*365.25)

JATechSpecialis :

Make sure the format of the cell is "Date"

Customer:

that formula is for the age of 39.05 being TODAY.

JATechSpecialis :

Age 39.05 should be in A1

JATechSpecialis :

and the cell in which you put this formula should be in Date(Right click > Format cells > Choose date)

Customer:

yes, but the age of 39.05 is as of march 31, 2013 which is 9 days ago. the formula you are giving me is for the age of 39.05 being today.

JATechSpecialis :

Sorry

JATechSpecialis :

You can replace today with 3/31/2013

Customer:

ah. ok. let me try it. so the forumla should be:

JATechSpecialis :

I need to modify it a bit, give me some time please

JATechSpecialis :

If you replace today with the date it will not work I guess, need to analyze it

Customer:

what i did was add .05 to 39.05 and then used today

JATechSpecialis :

JATechSpecialis :

So if the persons age is 39.05 on 31-Mar

JATechSpecialis :

the formula should be

Customer:

ok. hold on so the formula should be

Customer:

=(3/31/2013()-A1*365.25)

JATechSpecialis :

No it will give an error

JATechSpecialis :

It should be in this format

JATechSpecialis :

=(J5-F11*365.25)

JATechSpecialis :

where J5 contains the 31-Mar-2013 date and F11 contains the age

JATechSpecialis :

as of that date

Customer:

sorry. not following.

JATechSpecialis :

Ok, lets say cell A1 contains 39.05 which is the age as of 31-Mar

Customer:

oh hold on i get it now. let me try

JATechSpecialis :

sure

Customer:

no, wait. i have one cell with the age being the value of 39.05 on march 31.

Customer:

i think i need to just add the .05 to get 39.1 and then use the "Today" formula to get the date of birth and then take the date of birth to generate new numbers based on "Today" going forward.

JATechSpecialis :

you can do that but adding 0.05 will only work if the age is of Mar-31 only

JATechSpecialis :

moreover, it may not be accurate for some cases

Customer:

yes that is the age for march 31 only.

Customer:

so how do i get

JATechSpecialis :

But I will suggest you to use the date directly

Customer:

you are suggesing i use this:

Customer:

you recommended i used this formula:

=(J5-F11*365.25)

where J5 contains the 31-Mar-2013 date and F11 contains the age

Customer:

but my value is 39

Customer:

my value is only one cell

Customer:

i do not have two cells

JATechSpecialis :

I will tell you how to do that

Customer:

one cell only.39.05 which represents the age on march 31, 2013

JATechSpecialis :

Try this formula

JATechSpecialis :

=(41364-A1*365.25)

JATechSpecialis :

A1 contains the age

Customer:

ok. a1 contains age. hold on.

JATechSpecialis :

yes

Customer:

hmmm. it is on average about ten days different from my attempt at adding .05 to the 39.05 and using the "Today" formula.

Customer:

JATechSpecialis :

It can't be totally accurate, do you want it like that?

Customer:

i guess it will have to do.

Customer:

unless you can think of anything else.

Customer:

how did you arrive at the =(41364-A1*365.25) forumla?

JATechSpecialis :

calculating age from dob is different but vice versa can't be 100% accurate

Customer:

ok. well if that is as good as it gets. i guess it will have to do.

JATechSpecialis :

41364 is the numeric format of 31-Mar-2013 date

Customer:

definitely better than nothing i guess

Customer:

oh.....right!

Customer:

where did you find that?

Customer:

it makes sense now.

JATechSpecialis :

Using Excel

Customer:

what do i do now?

Customer:

this is the first time i have used this service.

Customer:

you found the numeric value of march 21, 2013 where in excel?

JATechSpecialis :

just type the date into a cell in excel

JATechSpecialis :

and format it to numeric value

JATechSpecialis :

general or number without decimals

Customer:

WOW. got it.

JATechSpecialis :

most of the people try to convert DOB to age :)

JATechSpecialis :

JATechSpecialis :

hope you are happy with my help. ;)

Customer:

i know. but i work in HR and i have the AGES of employees and have to figure out their date of birth in the absense of that information from a company that my company is acquiring.

Customer:

very exhausting.

Customer:

and i thought i didnt know how to use excel. NO ONE knows how.

Customer:

everyone PRETENDS to know how.

Customer:

i freely admit i do not know how to do something, but seem to be more capable than some people.

Customer:

how do i pay for this?

JATechSpecialis :

Got it, yes you are

JATechSpecialis :

I can see that

JATechSpecialis :

You can use the smiley buttons below to rate me.

Customer:

ok. where are you located btw? i am in vancouver

JATechSpecialis :

I will try to find something to convert age to DOB more accurately

JATechSpecialis :

If I get anything, I will reply here.

Customer:

oh. do you think you could?

JATechSpecialis :

I am located in Bangalore, India :-)

Customer:

reply here. will it get forwarded to me?

JATechSpecialis :

I will try. Since dates don't follow a symmetrical pattern, this problem arises

JATechSpecialis :

Customer:

wow. that would be greatly appreciated. thank you for your help

Ansh P., MS Office Specialist
Category: Microsoft Office
Satisfied Customers: 8147
Experience: Computer Science Engineer with 10 years experience in MS Office (All Versions).

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