Percentage Calculator
Calculate percentages, percentage changes, increases, and decreases
Enter values and click "Calculate" to see your result
Percentages used to hurt my brain, you see. I mean it. If a restaurant receipt said "find 15 percent of $80," I would wing it with the tip. After that, my cousin—who has an odd aptitude for math—showed me how easy this stuff is. I genuinely know what I'm doing now.
X Percent of Any Number Can Be Found
Let's say you need 25% of 200. What I do is this:
When the percent sign is removed, divide by 100 and then multiply. I consider percentages to be parts per hundred. 25 percent scaled up to whatever number I'm working with means I want 25 parts out of every 100.
How Much of a Change Was There?
It keeps coming up: how much did my electricity bill increase, how much weight did I lose, and so on. We'll assume that your bill increased from $100 to $120.
$20 is the difference between $120 and $100.
$20 ÷ $100 = 0.20 is the result of dividing by the initial.
In percentage terms: 0.20 × 100 = 20% increase.
Increasing Something by a Percentage
I discovered there are two methods to add 20 percent to 100:
The lengthy method: 100 + (100 × 20 ÷ 100) = 120
The shortcut: 100 × 1.20 = 120 (since 1.20 is equal to 100 percent plus 20 percent)
These days I always take the shortcut. Significantly less labor.
And What Percentage of That Is This?
For example, you answered 25 of the 100 questions correctly. Simply divide by 100 and the result is:
Things I Do Use This For:
- • Tipping at restaurants: 18% of $47.50 is equivalent to about $8.55
- • Sales at the store: 40 percent off $75 = I pay $45
- • Monitoring progress: Weight loss of 6-7% from 150 to 140 pounds
All of this is automatically handled by the calculator above, but knowing the math is useful when you're not using your phone.