How To Keep A Constant In Excel And Other Spreadsheets

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When creating a formula in Excel or most other spreadsheet programs we sometimes need one of the values to be dynamic (e.g. we can change it in one place and effect everywhere it’s referenced) but stay constant when we replicate that formula across rows or columns.

To keep a constant value in Excel use the following steps:

1. Create a cell with the constant value you want to reference
2. Create a formula in a cell that performs your calculation
3. In the formula where you reference the value you created in step 1, add a “$” before the letter (representing the column) and number (representing the row).

Example of Keeping A Constant Value in Excel

We have a cell, let’s say cell A1 which just contains the text “Interest Rate” which is simply a label so we know what we’re dealing with.

Next, we have a cell B1 which contains the actual interest rate, we’ll represent our percentage as a decimal so 10% becomes .1.

Now below that we have three columns:

1. Principal Amount
2. Simple Interest
3. Total (Principal Amount + Simple Interest)

in A3 we put $1000, in A4 we put $2000 then highlight both cells and grab the bottom right corner and drag down for 8 more rows so you now have values $1000 – $10,000.

Next in B3 we enter a formula to calculate interest by multiplying our first value ($1000 in cell A3) by the interest rate (.1 or 10% in B1).

=(A3*B1)

The cell should show $100.

Now, as with creating the 10 rows in increments of $1000, we can grab the bottom right corner and drag down. The problem is that both references will change cells but we only want the first one (principal amount) to calculate from the next cell down (A4, A5 and so on). we want the interest rate cell to always be calculated from B1 (not B2, B3, etc… as the spreadsheet will naturally assume).

So to fix this we add the “$” before the Column letter and Row number for our interest rate cell changing the formula in B3 to now look like this:

=(A3*$B$1)

Now when we grab and drag the interest rate will always be calculated from the value in B1.

Finally, just to round things out, lets do another forumla in C3 to add Principal to Interest using the simple formula =(A3+B3) in C3.

Now grab and drag C3 down and you’ll see the increments increase and we now know how much simple interest we’ll make in a year on $1000 – $10,000.

Want to see things change? Modify the .1 in cell B1 to .05 (5%) and everything will change across the board.

What are your favorite excel tips and tricks? Need help figuring out something in a spreadsheet? Hit me up on twitter @vsellis or google+ at gplus.to/scottellis.

Learn something new everyday!