percentage calculator in excel

How to calculate percentage in Excel

If you work with budgets, sales dashboards, marketing performance, grades, or financial reports, percentage calculations are unavoidable. The good news is that Excel makes these calculations simple once you understand a few core formulas.

This guide gives you both an interactive calculator and practical formulas so you can calculate percentages quickly and correctly inside Excel.

Most useful Excel percentage formulas

• Find X% of a number: =B2*C2 (if B2 is already formatted as a percent) or =B2*C2/100
• Find what percent A is of B: =A2/B2 then format as Percentage
• Percent increase/decrease: =(New-Old)/Old
• Add a percentage: =A2*(1+B2)
• Subtract a percentage: =A2*(1-B2)

Example scenarios you can use right away

1) Calculate tax, commission, or discount

If your price is in A2 and tax rate is in B2, use:

• Tax amount: =A2*B2
• Total price with tax: =A2*(1+B2)

For discounts, use =A2*(1-B2).

2) Calculate contribution to total

If each department's sales are in B2:B10, and total sales are in B11, the share of each department is:

=B2/$B$11

Format as Percentage and drag down for the full list.

3) Calculate month-over-month growth

If January is in B2 and February is in C2, growth is:

=(C2-B2)/B2

This returns positive values for growth and negative values for decline.

Formatting percentages correctly in Excel

Formatting errors are one of the biggest reasons people get percentage calculations wrong. Keep these rules in mind:

• If you type 15%, Excel stores it as 0.15.
• If you type 15 and format as Percentage, Excel shows 1500%.
• Use decimal rates (0.15) or literal percent entries (15%) consistently.
• Apply Percentage format from the Home tab for cleaner results.

Common mistakes to avoid

• Dividing by zero: when the base value is 0, percentage formulas break.
• Mixing percent formats: entering some values as 15 and others as 15% causes bad results.
• Wrong denominator: for "part of whole", always divide part by total (not total by part).
• Forgetting absolute references: use $ for fixed totals, e.g., $B$11.

Pro tip: combine with IFERROR

For cleaner dashboards, wrap percentage formulas with IFERROR:

=IFERROR((C2-B2)/B2,0)

This avoids ugly #DIV/0! errors in reports.

FAQ: percentage calculator in excel

How do I calculate 20% of a number in Excel?

Use =number*20% or place 20% in a cell and multiply: =A2*B2.

How do I show result as percent instead of decimal?

Select the result cell, go to Home > Number, and choose Percentage.

How do I calculate percentage increase from one value to another?

Use =(new-old)/old and format as Percentage.