# Thread: Calculating time to age 70

1. Hi loungers....I am having a small problem with a formula that I use to calculate ages....I start with a birthdate in column B, and in column C have the date when the person turns age 70.....in col C, the date of turning 70 doesn't always fall on the same birth'day'.....see attached sample.....I am sure is has something to do with leap years, even though I am multiplying 70 years x 365.25 days (to account for leap years)......and in col D, I tried using 70*365.258, but that reversedthe problem....see sample......is there some formula that I can use that 'compensates' for this or, perhaps sees it as an error and willl adjust for it? Thanks for any help.

2. [quote name='dmcnab' post='776291' date='21-May-2009 11:05']Hi loungers....I am having a small problem with a formula that I use to calculate ages....I start with a birthdate in column B, and in column C have the date when the person turns age 70.....in col C, the date of turning 70 doesn't always fall on the same birth'day'.....see attached sample.....I am sure is has something to do with leap years, even though I am multiplying 70 years x 365.25 days (to account for leap years)......and in col D, I tried using 70*365.258, but that reversed the problem....see sample......is there some formula that I can use that 'compensates' for this or, perhaps sees it as an error and willl adjust for it? Thanks for any help.[/quote]
Where the birthdate is in cell B1, why not use =DATE(YEAR(B1)+70,MONTH(B1),DAY(B1)) to calculate 70th birthday

3. That works very nicely, John...thank you

4. [quote name='JohnBF' post='776297' date='22-May-2009 04:15']Where the birthdate is in cell B1, why not use =DATE(YEAR(B1)+70,MONTH(B1),DAY(B1)) to calculate 70th birthday[/quote]
Just in case the birthdate was on 29 February, a more reliable formulation is =MIN(DATE(YEAR(B1)+70,MONTH(B1)+1-{1,0},DAY(B1)*{1,0}))

5. Paul--thank you for that neat variation----I hadn't even thought of that, but it is something that I will build into the formula....have a good weekend

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