If you need resulting date and end date and you already have add orsub, start date, initial date, time difference and time difference, this calculator does the substitution for you. It suits a quick check, a homework answer you want to confirm, or any figure you need to sanity test.
What Is the Date Calculator?
The date calculator turns add orsub, start date, initial date, time difference and time difference into resulting date and end date.
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 Date 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 add orsub set to 1, start date set to 10, initial date set to 5, the calculator returns end date of 12, and resulting date of 105. Substitute your own figures and the same steps produce the same kind of answer.
Frequently Asked Questions
What do I need to work out resulting date?
Enter add orsub, start date, initial date, time difference and time difference. The calculator then works through the relationship and reports resulting date and end date.
What does the date actually calculate?
It takes add orsub, start date, initial date, time difference and time difference and converts them into resulting date and end date 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 add orsub?
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.
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.
Can I use this for a quick estimate as well as a precise answer?
Yes. The calculator is built for quick checks, so round your inputs to a sensible number of significant figures and the result will be just as useful. If you need more precision, keep the same method and add digits to the inputs rather than adjusting the method itself.