Percentage Calculator
This is the percent tool I wish I had in school. It does the three sums we all need.
Percent of a sum, a sum as a percent, and percent change. Pick your mode and go.
How to use this tool
- 1For percent of a sum: the sum times the percent split by 100.
- 2For a part as a percent: the part split by the whole times 100.
- 3Add and take modes work the percent on to the sum in one go.
The math behind it
Part = whole x percent / 100
What is 15 percent of 240? Multiply 240 by 15 and split by 100.
The answer is 36.
Who this tool is for
I watch which tools folk open most, and this one gets used by the same kinds of people again and again. If any of these sound like you, you are in the right place.
- Students and any one rusty on percent math
- Shoppers checking adds and takes in one place
- Workers checking fees against sums
I keep a note on my phone that says just percent, and it is full of sums like this. Tip on a service, fee on a payment, a part as a slice of a whole. Percent questions come at you in five shapes. This tool holds all five shapes so my phone note can retire.
Tips from me
- Type what you know in any mix. The tool flips the sum for you.
- Percent of vs percent off are different sums. Read the label twice.
- For money, keep two decimals. For big counts, round to whole units.
Mistakes I see with this sum
These are the three slips I made my self or watch folk make most. Skip them and your number will be closer to the truth on the first try.
- 1Typing the part in the whole box in the is what percent mode.
- 2Forgetting that more than 100 percent is a real and normal answer.
- 3Mixing up a percent change with a percent of a sum. Different sums, same words.
Two words worth knowing
Percent
A slice out of 100. 25 percent is 25 of every 100.
Base
The whole sum the percent sits on.
That is the whole page. The tool does the math, and the words above give it a shape. If a number still looks odd, change an input and watch what moves. Playing with the boxes taught me more than any guide did.
Common questions
+How do I work out a percent by hand?
Part split by whole, times 100. Or whole times percent, split by 100. Same two moves this tool uses.
+Why is my answer more than 100 percent?
That means the part is bigger than the whole. It happens. 250 out of 200 is 125 percent.
+How do I turn a percent in to a decimal?
Split by 100. Twenty five percent becomes 0.25, which makes the mental math easy.
+What is the difference between percent and percentage points?
Percent is a share of a whole. Percentage points are the gap between two percents. Two percent to five percent is three points.
+Why does my percent of a percent look odd?
Percent of a percent is a percent of a smaller thing. Five percent of twenty percent is one percent, not twenty five.