# Date Calculator

## What is a date calculator?

Essentially there are a number of methods which are put in to use to calculate the date or for that matter the day of the week. An individual will be in a position to calculate the date either in the past or the future with the help of this date calculator. In addition to this, to calculate the date as well as the day of the week, a lot of algorithms form the base for such a calculation. The best part of this is that though the tables which are found in the perpetual calendars do not require any sort of a calculation still they make use of the algorithms to arrive at the solution.

## Date Difference Calculator

 From Date : To Date :

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## How is the date & day determined?

As far as the determination of the date & day of the week is concerned that too from the numerical operations then the following aspects are to be kept in mind. Sunday through to Saturday, these are represented by numbers such as 1 to 7. To get to this the arithmetic modulo 7 is put in to use. This modulo 7 happens to be the operation which helps in calculation of the reminder of a certain number that is further divided by 7.

### What is the formula used in the date calculator?

The basic formula used in a date calculator is as follows –

$$(\,d\,+\,m\,+\,y\,+\,[\frac{y}{4}]\,+\,c\,)\, mod\, 7$$

In the above equation, d is stated to be the day of the month while m is the month’s number (as per the month’s table). In addition to this, y means it is the last 2 digits of a year & c is the century’s number according to the ‘100s of Years’ table.

However, now a days, people are using another simple formula when the date calculator is in question. And this formula has also been mentioned below –

$$365\,\times \, year\, + \frac{year}{4}\,-\, \frac{year}{100}\,+\, \frac{year}{400}\,+\,date\,+\, \frac{153 \, \times \, month\, +8}{5}$$

## What is the use of the date calculator?

In simple words, a date calculator is quite helpful & the reason for the same has been given here as well. There are basically 2 date calculators which one can see on this page. On one hand, 1 calculator will be used to compare the difference between the 2 dates while on the other hand, the other calculator’s purpose would be to either add or to subtract the days / weeks / months / years from the given date.

## How to use a date calculator?

To make use of the date calculator & especially when the number of years, months, weeks, & days between 2 dates are concerned then the following steps are to be followed – firstly, you will have to enter the date followed by month & the year, remember this will be the start date & then enter the end date. Click on calculate tab to know the result. And when you wish to subtract or add from a given date then enter the start date followed by the years, months, days & the weeks & click on calculate.