Start with the equals sign, then type what you want to calculate

Every calculation in Excel begins with an equals sign. Type = into any cell, followed by the numbers or cell references you want to work with, and Excel performs the math. The most common operations are addition (+), subtraction (−), multiplication (*), and division (/). For example, =5+3 gives you 8, and =A1+B1 adds whatever numbers sit in cells A1 and B1.

The real power comes from using cell references instead of typing numbers directly. If you have a list of expenses in column A and you want to add them all up, you write a formula that points to those cells. When the numbers change, the formula recalculates automatically — you do not have to rewrite it.

Excel follows the standard order of operations: multiplication and division happen before addition and subtraction. If you need a different order, use parentheses. =10+5*2 gives 20 (multiply first), but =(10+5)*2 gives 30 (add first).

Key Takeaways

  • Every formula starts with = and can use cell references (like A1) or numbers, with operations +, −, *, and / performing basic math.
  • SUM adds a range of cells at once, AVERAGE finds the middle value, COUNT tallies how many cells hold numbers, and MAX or MIN find the highest or lowest.
  • When you copy a formula down or across, cell references shift automatically — A1 becomes A2, A3, and so on — unless you lock them with dollar signs.
  • Parentheses control the order of operations, so =(10+5)*2 multiplies the sum by 2, not just the 5.
  • The formula bar at the top shows what is actually in a cell, so you can see and edit formulas without clicking inside the cell itself.

Use SUM to add ranges of cells quickly

SUM is the most common function in Excel. Instead of typing =A1+A2+A3+A4+A5, you write =SUM(A1:A5). The colon means "through," so A1:A5 means all cells from A1 to A5 in one go. This saves time and makes formulas easier to read.

You can also sum non-consecutive cells. =SUM(A1:A5,C1:C5) adds cells A1 through A5 and C1 through C5, skipping column B. The comma tells Excel to add multiple separate ranges together.

SUM ignores empty cells and text, so it works even if your data has gaps. If a cell contains a word or a blank space, SUM skips it and adds only the numbers.

Find averages, counts, and highest or lowest values

AVERAGE calculates the mean of a range. =AVERAGE(A1:A10) adds all ten numbers and divides by ten. Like SUM, it ignores empty cells and text.

COUNT tells you how many cells in a range hold numbers. =COUNT(A1:A10) returns the number of cells with actual numbers in them, not text or blanks. This is useful when you have a messy list and want to know how much data you actually have.

MAX and MIN find the largest and smallest values. =MAX(A1:A10) returns the highest number in that range, and =MIN(A1:A10) returns the lowest. Both ignore text and empty cells.

Copy formulas down or across without retyping

Once you write a formula in one cell, you can copy it to others. Click the cell with your formula, then drag the small square in the bottom-right corner down or across to fill adjacent cells. Excel automatically adjusts the cell references for you.

If you have =A1+B1 in cell C1 and you drag it down to C2, it becomes =A2+B2. The row numbers shift because you moved down one row. This is called a relative reference, and it is the default behavior.

Sometimes you want a reference to stay the same when you copy. Use a dollar sign before the letter or number you want to lock. =$A$1 never changes, no matter where you copy it. =A$1 locks only the row, so the column shifts but the row stays 1. =$A1 locks only the column, so the row shifts but the column stays A. These are called absolute references.

Use the formula bar to see and edit what is inside a cell

The formula bar sits at the top of the spreadsheet, just below the ribbon. When you click any cell, the formula bar shows exactly what is in it — whether a number, text, or a formula. This is where you can see the full formula if it is too long to fit in the cell itself.

You can edit a formula by clicking in the formula bar and making changes there, or by double-clicking the cell itself to edit directly inside it. Either way, press Enter when you are done and Excel recalculates the result.

The formula bar is also where you can see if a cell contains a formula or just a number. A cell showing 45 might actually contain the formula =SUM(A1:A10) — you cannot tell just by looking at the cell, but the formula bar reveals it.

Understand how parentheses change what gets calculated first

Excel calculates multiplication and division before addition and subtraction, just like math class. =2+3*4 gives 14, not 20, because 3*4 happens first. If you want the addition to happen first, wrap it in parentheses: =(2+3)*4 gives 20.

You can nest parentheses too. =((A1+A2)*B1)/C1 adds A1 and A2, multiplies by B1, then divides by C1. Excel works from the innermost parentheses outward, so the order is clear and predictable.

When formulas get complex, parentheses make them readable. A formula like =SUM(A1:A10)*0.1 is clearer than trying to remember which operation happens first.

Common mistakes and how to spot them

If a cell shows #NAME?, you likely misspelled a function name. Excel does not recognize =SUM spelled as =SUMM. Check the spelling and try again.

#DIV/0! means you tried to divide by zero or by an empty cell. =A1/B1 will show this error if B1 is blank or contains 0. Make sure the cell you are dividing by has a non-zero number.

#REF! appears when a formula points to a cell that no longer exists — usually because you deleted a column or row that the formula relied on. Edit the formula to point to the correct cells.

If a formula does not update when you change a number, check that the cell is formatted as a number, not text. A cell that looks like it holds a number but is actually formatted as text will not calculate. You can also press Ctrl+Shift+F9 (or Cmd+Shift+F9 on Mac) to force Excel to recalculate all formulas.

Frequently Asked Questions

Can I use a formula that refers to cells in a different sheet?

Yes. Type the sheet name, then an exclamation mark, then the cell reference. For example, =Sheet2!A1+B1 adds the value in cell A1 of Sheet2 to the value in B1 of your current sheet. If the sheet name has spaces, wrap it in single quotes: ='Sheet 2'!A1.

What is the difference between = and ==?

In Excel, you use a single equals sign (=) to start any formula or calculation. A double equals sign (==) is not standard Excel syntax. If you are thinking of comparison, Excel uses = to assign or calculate, and uses comparison operators like > (greater than), < (less than), and = inside IF statements to test conditions.

How do I make a formula that only calculates if a condition is true?

Use the IF function. =IF(A1>10,"Yes","No") checks if A1 is greater than 10 and displays "Yes" if true, "No" if false. You can also nest IF statements or combine them with other functions like SUM: =IF(A1>0,SUM(A1:A10),0) adds the range only if A1 is positive.

Why did my formula stop working after I deleted a row?

If your formula pointed to cells in that row, deleting it breaks the reference and shows #REF!. If the deleted row was outside your formula's range, the formula should still work but the cell references may have shifted. Click the cell with the error and check the formula bar to see what went wrong, then edit it to point to the correct cells.