How dates and times work in Google Sheets

How Dates Work

Though it may not be obvious initially, spreadsheets store dates as numbers instead of text. You can show dates in many different formats to the user, but their underlying value doesn’t change.

To illustrate the concept of the format changing but not the value, all of the rows in this table consist of 42734 displayed differently.

42734No formatting applied
12/30/2016Format -> Number -> Date
12-30-2016Format -> Number -> More Date and Time Formats…
12/30Format -> Number -> More Date and Time Formats…
Friday, December 30, 2016, 12:00:00 AMFormat -> Number -> More Date and Time Formats…

Using Dates in Formulas

If you use dates in formulas, you must be careful to use them correctly. If you write something like =12/31/15-12/31/14, the result will be -.002, which wouldn’t be what you were looking for. Sheets will think you are dividing because of the slashes instead of showing dates. A similar error will occur if you try =12-31-15-12-31-14. The separators for dates, slashes or hyphens, are also arithmetic operators.

To work around this, use quotes to surround them. Let’s look at a few examples. The first example is misinterpreting slashes as division operators. The second example is misinterpreting dashes as subtraction operators. The formula is written and interpreted correctly using quotes to surround each date value until the third example.

-0.000860215053763443Written as =12/31/15-12/30/15
-91Written as =12-31-15-12-30-15
1Written as =”12/31/15″-“12/30/15”

Tip: If you are not in the United States, you may need to change your spreadsheet settings to show dates in the correct format for your location.

Screen capture of the spreadsheet settings for showing dates and times
Change your locale in the settings

If you enter dates in a non-US format, you may get the #VALUE! error. Let’s take December 31, 2016, as an example.

If you hover over the error, the explanation says, “Function MINUS parameter 1 expects number values. but ’31/12/16′ is a text and cannot be coerced into a number.” In other words, Sheets cannot convert 30/12/16 to 42,734, nor can it convert 31/12/16 to 42,735, so it cannot subtract the two values.

 entered as MM/DD/YYentered as DD/MM/YY
start12/31/1630/12/16
end12/31/1631/12/16
elapsed time1#VALUE!

Subtracting Two Dates: Example 1

The same value is formatted in different ways in columns 2 and 3. The elapsed time is subtracting the two values. The result is the same regardless of the format of the cells above. Also, note that the spreadsheet formatted the result as an integer. If the result were formatted as a date, it would display “12/31/1899,” which would not make sense for this operation.

 Formatted as dateFormatted as number
start12/30/1642,734.00
end12/31/1642,735.00
elapsed time11.00

Subtracting Two Dates: Example 2

The same value is formatted in different ways in columns 2 and 3. It is similar to example one, but you should look at this one too, just for giggles. Notice the extra day for leap year.

start12/31/1542,369.00
end12/31/1642,735.00
elapsed time366 (2016 was a leap year)366.00 (2016 was a leap year)

The Beginning of Time

According to Google Sheets, time started on December 31, 1899. However, the dates before this will still exist, but negative integers will represent them.

Formatted as a dateFormatted as a number
12/29/1899-1.00
12/30/18990.00
12/31/18991.00
1/1/19002.00

How Times Work

Times work similarly to dates in that they are shown as times, but they are numbers. One hour is .0417, which results from 1 hour divided by 24 hours in a day.

3:00 AMTyped as 3 AM, default formatting
9:00 PMTyped as 9 PM, default formatting
0.125Typed as 3 AM, changed the formatting to Number -> Automatic
.875Typed as 9 PM, changed the formatting to Number -> Automatic

How Dates and Times Work Together

Combining the two is easy once you understand how dates and times work.

12/31/16 3:00 AMTyped as 12/31/16 3 AM, default formatting
42735.125Typed as 12/31/16 3 AM, changed the formatting to Number -> Automatic

Live Examples in Sheets

Go to this spreadsheet for a live version of these examples so that you can study and use them anywhere you like.

Related Tutorials

Leave a Comment