Free calculator
Percentage calculator
Solve the percentage jobs that show up in pricing, discounts, planning, and reporting: percent of a number, how much one value is of another, the implied whole when you know a part and its percent, and how to raise or lower a single value by a percent. When you move the same math into a workbook, use the Sheets & Excel section for copy-ready formulas.
When to use this calculator
Typical top-of-funnel checks—fast, transparent, and independent of any one spreadsheet file.
- Quickly find p% of an amount (discounts, fees, or commission lines).
- Express one metric as a percent of another (share of revenue, mix, or attainment).
- Back-solve the whole when a line item is “p% of total” and you only know the part.
- Apply a single percent increase or decrease to a baseline (planning scenarios—not the same as A→B percent change).
Each tab is one standard percentage identity. Pick the tab that matches your wording, enter your numbers, and match the on-screen result to the identity for that mode.
p% of x (percent of)
Identity: part = x × (p ÷ 100)—same as the first tab.
x is what % of y (share)
Identity: 100 × (x ÷ y). In Sheets or Excel you often write =x/y and set Percent number format instead of baking 100 into the formula.
x is p% of what (implied whole)
Identity: whole = 100 × (x ÷ p) with p ≠ 0—same as the reverse tab. Make sure p matches how your sheet stores the rate (for example 15 for 15%, unless you intentionally use decimals).
Increase or decrease one base by p%
Identity: adjusted = base × (1 ± p ÷ 100) with the sign that matches increase vs decrease.
The Increase / decrease tab applies p% forward to one starting value. That is not the same as percent change between two already-known totals ((new − old) ÷ old); see the FAQ when you need both ideas side by side.
Rounding, number formats, percentage points, and two-number percent change are covered in the FAQ below.
Google Sheets & Excel formulas
Copy these patterns into your cells—replace x, y, p, or base with your references (for example =A2*(B2/100) when A2 is the amount and B2 stores 15 for 15%).
=x*(p/100)Example: =A2*(B2/100) when A2 is the number and B2 is the percent as a plain number (15 means 15%).
=x/yFormat the cell as Percent, or use =100*x/y if you want a numeric ratio without percent formatting.
=x/(p/100)Algebraically equivalent to =100*x/p when p is not zero—double-check p references a percent value, not a decimal, unless you intend decimals.
Increase
=base*(1+p/100)Decrease
=base*(1-p/100)Pick the line that matches your direction. Increase / decrease here applies to one base value; percent change between two different totals uses ((new − old) ÷ old) instead—see the FAQ.
Frequently asked questions
What is a percentage?
A percentage expresses a number as parts per hundred. 25% means twenty-five hundredths of a whole, the same idea as writing 0.25 in decimal form.
How do I calculate p% of a number?
Multiply the number by the percent, then divide by one hundred. On this page we show the result as part = x × (p ÷ 100). People often call that the “percent of” or “percentage of” the whole.
What is the difference between percent change and percentage points?
Percent change compares two values relative to a starting amount. Percentage points describe the simple difference between two percentages—for example moving from 10% to 12% is a change of two percentage points, not “2%” in the multiplicative sense.
How do I calculate percentage change from one number to another?
When you have an old value A and a new value B, relative change is ((B − A) ÷ A) × 100. That answers “how much did this total move?” The Increase / decrease tab on this page is different: you enter one base value and a percent to apply forward. Build the two-number comparison once in your sheet if you need it on every row.
How do I do the same math in Google Sheets or Excel?
The patterns in the Google Sheets & Excel formulas section match these one-liners: =x*(p/100) for percent of; =x/y with Percent format (or =100*x/y) for share; =100*x/p or =x/(p/100) for implied whole when p ≠ 0; =base*(1+p/100) / =base*(1-p/100) for increase or decrease. If a cell stores decimals (for example 0.25), percent formatting can display 25%.
How does rounding work here?
We compute with full floating-point precision and format the on-page result for readability. Your spreadsheet may show different decimal places depending on cell formatting.
When do I use “x is p% of what?”
Use it when you know a part and the percent it represents, and you need the implied whole—for example a line item that is 15% of revenue and you want the revenue that makes that true.
Is this financial advice?
No. This page is a free educational helper for arithmetic you already use in models. It does not know your business, tax jurisdiction, or contracts—talk to a qualified professional when decisions matter.