Dates are numbers

How many days passed between January 20 and February 4? To answer, you don't need to flip through a calendar: in Excel, you just subtract one date from the other. This works because every date is stored in a cell as a number.

The day number

Excel numbers days starting from January 1, 1900: that day has the number 1, the next one 2, and so on. February 1, 2026 gets the number 46054.

The cell stores this number, and the Short Date format shows it as a month, day and year:

How many days between dates

Since dates are numbers, regular signs work with them:

• the difference between two dates equals the number of days between them: =C2-B2;
• a date plus a number gives the date that many days later: =B2+14.

Below are invoices with the dates they were issued and paid. Column D already has the difference between the dates. Look at what it shows:

Excel calculated correctly, but it gave the new cells the format of the neighboring cells, the date format. So it showed the number of days as a day number, that is, as a date from the very start of the count, January 1900. The General format shows the number itself: invoice #101 was paid after 15 days, one day past the deadline.

In column E, the date format fits: a date plus days is exactly the date by which the invoice had to be paid.

Today's date

Invoice #104 was issued on September 1, and it still hasn't been paid. How many days the client has been delaying the payment is counted with the TODAY function: it returns today's date. It has no arguments, but the parentheses are required:

=TODAY()-B2

The date updates by itself: tomorrow the answer will be one more, and you won't need to rewrite the formula.

A date written as text

A date from an export sometimes turns out to be text: it's aligned to the left edge of the cell, there's no day number inside, and COUNT skips it. One such date is easier to type again, and a whole column is fixed by the Text to Columns button on the Data tab. Excel enters each cell again, as if it had been typed, and recognizes the date in it.

The main points

• Excel stores a date as a day number, so you subtract and shift dates with regular signs: =C2-B2, =B2+14.
• If a difference between dates looks like a date from 1900, give the cells the General format.
• TODAY() returns today's date and updates by itself every day.