The age to birthday calculator works out age from date of birth, date of birth, on… and on…. Enter what you have and the relationship is applied straight away, so you get the answer without working through the algebra yourself.
What Is the Age to Birthday Calculator?
The age to birthday calculator turns date of birth, date of birth, on... and on... into age.
It is a quick way to get from the numbers you have to the number you need, without setting up a spreadsheet or reaching for a formula.
How the Age to Birthday Works
Each result follows from the ones before it, and the calculator shows every step, so a surprising answer can be traced back to the input that caused it.
Round your inputs to the precision you actually know, and keep more precision than that in the intermediate steps.
Getting a Result You Can Trust
Run the calculation twice with slightly different inputs. A sensible calculator moves its output in proportion; a wild change points to a unit or a decimal point problem in what you entered.
Write the inputs down next to the answer. It takes a moment and it is the difference between a number you can explain and one you cannot.
A Worked Example
Working through an example, with date of birth set to 10, date of birth set to 5, on... set to 2, the calculator returns age of -0.02, and age (age2) of 0. Substitute your own figures and the same steps produce the same kind of answer.
Frequently Asked Questions
What do I need to work out age?
Enter date of birth, date of birth, on... and on.... The calculator then works through the relationship and reports age.
What does the age to birthday actually calculate?
It takes date of birth, date of birth, on... and on... and converts them into age using the standard relationship for this problem. Each step is applied in turn, so every output is traceable back to the numbers you typed in.
How should I enter date of birth?
Use the value you actually have, in the unit shown next to the field. Enter every value in the same unit system. The calculator assumes the figures you supply are consistent, so it cannot correct a mistake that happens before the calculation starts.
Why does a small change in one value move the answer so much?
That happens when an output depends on a ratio, because dividing by a small number magnifies any change in it. Check the units first, then check whether the value you entered is in the range the relationship was designed for.
Is the answer exact?
It is as exact as the formula and the inputs allow. The method itself is the standard one for this problem, so the only sources of error are the figures you enter and the precision you ask for.