What calculating a percentage of a percentage means
A percentage of a percentage is a two-step calculation where you find a percentage of a number, then find a percentage of that result. For example: if a product costs $100 and you get a 20% discount, the new price is $80. If that discounted price then goes on sale for 10% off, you are finding 10% of $80, not 10% of the original $100. Excel handles this with a single formula that multiplies the percentages together, which is faster and more accurate than calculating each step separately.
This comes up in real situations: calculating commission on a bonus, finding the remaining value after two price cuts, or determining what portion of a reduced budget gets allocated to a specific department. The math is straightforward once you know which cells to reference and in what order.
Key Takeaways
- To find a percentage of a percentage in Excel, multiply the starting number by the first percentage, then multiply that result by the second percentage, or multiply all three in one formula.
- The formula =A1*B1*C1 (where A1 is the starting amount, B1 is the first percentage as a decimal, and C1 is the second percentage as a decimal) calculates both steps at once.
- Convert percentages to decimals by dividing by 100 — so 20% becomes 0.20 — or use the percentage format in Excel and let it handle the conversion automatically.
- Breaking the calculation into separate columns makes it easier to check your work and adjust individual percentages without rewriting the formula.
Setting up your spreadsheet with the starting amount and percentages
Start by entering your numbers in separate cells so you can see each part of the calculation. Put the starting amount in one cell — say A1 — and label it clearly. In B1, enter the first percentage. In C1, enter the second percentage. For example: A1 might be 1000 (your starting value), B1 might be 0.20 (which is 20%), and C1 might be 0.10 (which is 10%).
If you prefer to type percentages the way you see them — as "20%" instead of "0.20" — Excel will convert them automatically. Type 20% directly into the cell, and Excel stores it as 0.20 behind the scenes. Either way works; the key is being consistent so you do not accidentally multiply by 20 instead of 0.20.
Label each column so you remember what the numbers represent. Put "Starting Amount" above A1, "First Discount %" above B1, and "Second Discount %" above C1. This takes 30 seconds and saves confusion later when you come back to the spreadsheet in a week.
Writing the formula to multiply percentages together
In a new cell — say D1 — type the formula =A1*B1*C1. This multiplies the starting amount by the first percentage, then multiplies that result by the second percentage, all in one step. Press Enter, and Excel shows you the final answer.
If your starting amount is 1000, your first percentage is 0.20, and your second percentage is 0.10, the formula calculates: 1000 × 0.20 = 200, then 200 × 0.10 = 20. The result in D1 is 20. That is the percentage of a percentage.
You can also write this as =A1*(B1*C1) if you want to see the combined percentage first. This multiplies B1 and C1 together (0.20 × 0.10 = 0.02, or 2%), then multiplies that by A1. Both formulas give the same answer; use whichever feels clearer to you.
Handling percentages entered as whole numbers
If you entered 20 instead of 0.20 or 20%, you need to divide by 100 inside the formula. Type =A1*(B1/100)*(C1/100). This tells Excel to convert 20 to 0.20 before multiplying. If A1 is 1000, B1 is 20, and C1 is 10, the formula calculates: 1000 × (20/100) × (10/100) = 1000 × 0.20 × 0.10 = 20.
The reason: Excel treats 20 as the number twenty, not as 20%. To make it behave like a percentage, you divide by 100. This is a common source of wrong answers, so double-check how you entered your percentages before you trust the result.
Breaking the calculation into separate steps for clarity
Instead of doing everything in one formula, you can calculate each step in its own cell. Put the starting amount in A1. In B1, type =A1*0.20 to find 20% of A1. In C1, type =B1*0.10 to find 10% of the result from B1. This shows you the intermediate value (what the amount is after the first percentage), which makes it easier to spot mistakes.
This approach takes one extra cell but gives you more control. If you need to change the first percentage from 20% to 25%, you change only B1, and C1 automatically recalculates. If you need to see what the amount is after just the first discount, you can read it straight from B1 without doing math in your head.
Label each column: "Starting Amount" for A1, "After First %" for B1, and "After Second %" for C1. Anyone reading the spreadsheet — including you, three months later — will understand what each number represents.
Copying the formula down to multiple rows
If you have many starting amounts and need to calculate the percentage of a percentage for each one, enter your formula once, then copy it down. Put your starting amounts in column A (A1, A2, A3, and so on). Put your percentages in columns B and C. In D1, type =A1*B1*C1. Click on D1 to select it, then drag the small square at the bottom-right corner of the cell down to D10 (or however many rows you have). Excel copies the formula and adjusts the cell references automatically — D2 becomes =A2*B2*C2, D3 becomes =A3*B3*C3, and so on.
If your percentages are the same for every row, you can lock those cells so they do not change when you copy. In D1, type =A1*$B$1*$C$1. The dollar signs tell Excel to always use B1 and C1, even when the formula is copied down. Now D2 becomes =A2*$B$1*$C$1, which is what you want.
Checking your work with a straightforward example
Use a number you can calculate by hand to verify your formula is correct. If your starting amount is 100 and both percentages are 10%, the answer should be 1 (because 100 × 0.10 = 10, and 10 × 0.10 = 1). Enter 100 in A1, 0.10 in B1, 0.10 in C1, and =A1*B1*C1 in D1. If D1 shows 1, your formula is right.
Try another example: starting amount 200, first percentage 50%, second percentage 20%. By hand: 200 × 0.50 = 100, then 100 × 0.20 = 20. Enter these numbers into your spreadsheet and check that the formula gives 20. If it does, you can trust it with larger numbers and more complex percentages.
Frequently Asked Questions
Can I calculate three or more percentages of percentages in one formula?
Yes. Use =A1*B1*C1*D1 to multiply four values together, or add more cells as needed. The order does not matter — multiplying 0.20 × 0.10 × 0.05 gives the same result as 0.10 × 0.05 × 0.20. Each additional percentage is applied to the result of all the previous ones.
What if I want to show the combined percentage instead of just the final amount?
Multiply the percentages together and format the result as a percentage. Type =B1*C1 in a new cell (where B1 and C1 are your two percentages as decimals). If B1 is 0.20 and C1 is 0.10, the result is 0.02. Right-click the cell, choose Format Cells, select Percentage, and Excel displays it as 2%. This is the single percentage you could explore to the starting amount to get the same result as explore both percentages separately.
Why does my formula give a decimal instead of a percentage?
Excel is showing the number, not the format. The calculation is correct; you just need to format the cell as a percentage. Click the cell with your result, right-click, choose Format Cells, select Percentage from the Category list, and click OK. Excel multiplies the number by 100 and adds the % symbol, so 0.02 displays as 2%.
What if one of my percentages is negative?
The formula works the same way. If you are calculating a 20% increase followed by a 10% decrease, use 0.20 for the increase and -0.10 for the decrease. The result will be smaller than if you applied only the increase. Negative percentages are less common but the math is identical.
Can I use this to calculate what percentage one number is of another?
No — that is a different calculation. To find what percentage 25 is of 100, use =25/100 and format as a percentage (result: 25%). To find a percentage of a percentage, you are multiplying percentages together, not dividing numbers. Make sure you are solving the right problem before you write the formula.