How to write a formula in Excel

A formula is an instruction to work something out. You type it into a cell, and the cell shows the answer. Change any number the formula uses, and the answer changes by itself. That is the whole point of a spreadsheet, and everything else in Excel builds on it.

Every formula starts with an equals sign

Click a cell, type =, then what you want calculated, and press Enter.

=78+85+91
Result: 254
=C2+D2+E2
Result: 254
=(C2+D2+E2)/3
Result: 84.66666667

The first formula adds three numbers typed in by hand. The second adds the same numbers by naming the cells that hold them. The second way is the right way. If a mark is corrected in the sheet, the total corrects itself. A number typed inside a formula is hidden from view and easily forgotten.

Without the equals sign, Excel treats what you type as plain text and calculates nothing.

Sample sheet: Marks of eight students in three subjects. One Science mark is missing (cell D6 is empty).

	A	B	C	D	E
1	Name	Class	Maths	Science	English
2	Asha	8A	78	85	91
3	Ravi	8B	45	52	60
4	Meena	8A	92	88	79
5	Kabir	8B	33	41	38
6	Tara	8A	67		72
7	Joy	8B	88	90	84
8	Neha	8A	54	61	58
9	Imran	8B	78	73	69

The operators

Sign	Meaning	Example
`+`	add	`=C2+D2`
`-`	subtract	`=C2-D2`
`*`	multiply	`=C2*2`
`/`	divide	`=C2/2`
`^`	to the power of	`=C2^2`
`&`	join text	`=A2&" "&B2`
`=` `<>` `>` `<` `>=` `<=`	compare	`=C2>=33`

A comparison gives TRUE or FALSE.

=C2*2
Result: 156
=C2/E2
Result: 0.857142857
=C2^2
Result: 6084
=A2&" of class "&B2
Result: Asha of class 8A
=C2>=33
Result: TRUE

The order of calculation

Excel does not work from left to right. It follows the school rule: brackets first, then powers, then multiplication and division, then addition and subtraction.

=2+3*4
Result: 14
=(2+3)*4
Result: 20
=C2+D2+E2/3
Result: 193.3333333
=(C2+D2+E2)/3
Result: 84.66666667

The third formula divides only the English mark by 3. The fourth, with brackets, gives the average. When in doubt, add brackets. They never do harm.

Functions

A function is a ready-made calculation with a name. You give it values in brackets, separated by commas, and it returns a result.

=SUM(C2:E2)
Result: 254
=AVERAGE(C2:E2)
Result: 84.66666667
=MAX(C2:C9)
Result: 92
=ROUND(AVERAGE(C2:C9),1)
Result: 66.9

C2:E2 is a range: every cell from C2 to E2. A colon means "to". In the last formula, one function sits inside another. Excel works out the inner one first.

When you type = and the first letters of a name, Excel offers a list. Press Tab to accept a suggestion. A small tip then shows the arguments the function expects, with the optional ones in square brackets. Every function on this site is explained on its own page. The list of functions is the place to look.

Pointing instead of typing

You do not have to type cell addresses. After the equals sign, click the cell you want, or drag over a range. Excel writes the reference for you. It is quicker and avoids typing slips.

Copying a formula down a column

You write a formula once and copy it for every row. Select the cell and drag the small square at its bottom-right corner, the fill handle, down the column. Double-clicking the fill handle fills down as far as the neighbouring column has data.

As a formula is copied, its references move with it. =C2+D2+E2 in row 2 becomes =C3+D3+E3 in row 3. This is called a relative reference, and it is why one formula can serve a thousand rows. When a reference should not move, it is fixed with dollar signs. The guide on cell references explains how.

Looking at and editing a formula

The cell shows the result. The formula bar above the sheet shows the formula.
Press F2, or double-click the cell, to edit. The cells the formula uses are outlined in colours.
Press Ctrl and the grave accent key (the key under Esc) to switch the whole sheet between showing results and showing formulas.
Press Esc to abandon an edit that has gone wrong.

Text, numbers and dates in formulas

Text typed into a formula needs double quotation marks: =IF(C2>=33,"Pass","Fail").
Numbers are typed plainly, with no commas or currency signs: 1200, not 1,200.
Percentages can be typed with the sign: =C2*18%.
Dates are best built with the DATE function, not typed as text.

When the cell shows the formula, not the answer

If a cell displays =C2+D2 as text, one of three things has happened: the cell was formatted as Text before you typed, there is a space or an apostrophe before the equals sign, or Show Formulas is switched on. Set the format to General and enter the formula again.

When it shows an error

A result that starts with a hash sign, such as #DIV/0! or #NAME?, means Excel could not finish the calculation. Each one has a particular meaning and cure, set out in the guide to formula errors.

Good habits from the start

Put every figure that might change, such as a tax rate or a pass mark, in its own labelled cell, and refer to that cell. Do not bury it in formulas.
One formula per column, the same in every row. If row 7 needs something special, think again about the design.
Check a new formula against a calculation you do by hand for one or two rows.
Keep formulas short. Two simple columns are better than one formula nobody can read.

Every result on this page was calculated in Microsoft Excel (version 16.0, build 20326) on 12 November 2026, not typed by hand.

This is an independent help site. It is not connected with or approved by Microsoft. Excel and Microsoft 365 are trademarks of Microsoft Corporation, named here only to say which program a formula is for. The people and figures in the sample sheets are made up.