Percentage Formula in Excel: 5 Calculations You'll Use

Excel doesn't have a PERCENT function. Percentages are just division and multiplication, formatted with the % button. Here are the five calculations people need most.

1. What percent is A of B?

=B2/C2

Then click % on the Home tab. 45 out of 60 → 0.75 → 75%.

Don't multiply by 100 and also use % format, or you'll get 7500%.

2. Share of total (with $)

Each row's share of a total in B14:

=B2/$B$14

The $ keeps the total fixed when you fill down. Without it, row 3 divides by B15 and shows #DIV/0!. This is the classic test question. See absolute references.

3. Percentage of a number

20% of 250:

=250*20%
=B2*C2         (if C2 holds 20%)

4. Add or take off a percentage

Price plus 8% tax:

=B2*(1+C2)

Price after 15% discount:

=B2*(1-C2)

With one rate for every row, lock it: =B2*(1+$F$1).

5. Percent change

=(B3-B2)/B2

Full guide: percent change.

Formatting tips

• Ctrl + Shift + % applies percentage format.
• Increase decimals with the .00 button: 18.3% instead of 18%.
• Typing 20% into a cell stores 0.2, which formulas use correctly.

Reverse a percentage

The price was $108 including 8% tax. Before tax:

=B2/(1+8%)   → 100

Practise it

Shares of a total and "one rate, many rows" are core lessons in Cellio's "Copy formulas right" unit. Your formula is filled down the column like Excel does, so you see straight away if the $ is missing.

Frequently asked questions

How do I calculate a percentage in Excel?

Divide the part by the whole (=B2/C2) and format the result as %.

How do I calculate percentage of total in Excel?

=B2/$B$14, locking the total with $, then fill down.

How do I add 10% to a number in Excel?

=B2*1.1 or =B2*(1+10%).

Why does my percentage show 5000%?

You multiplied by 100 and applied % format. Do one or the other.