EstimatorPercentage Calculator
Six percentage tools in one: percent of a number, a number as a percent of another, increase, decrease, percent change and percent difference — results update as you type.
How it works
Every mode uses the same core idea — a percent is a fraction of 100. Percent of: (p ÷ 100) × number. Number as a percent: (part ÷ whole) × 100. Percent change: (new − old) ÷ old × 100. Percent difference is the one people mix up with change: it compares two numbers symmetrically, dividing by their average — |a − b| ÷ ((a + b) ÷ 2) × 100 — so it gives the same answer whichever order you enter the numbers.
When to use this
- A discount, tax or tip where you need the percent of a number, fast and exactly.
- Your grade, score or result expressed as a percentage of a total.
- Prices, weights or metrics moved and you need the percent change — up or down.
- Two numbers compared head-to-head as a percentage difference for a report or an argument.
How to use it, step by step
- Choose the mode that matches your question (percent of, as a %, increase, decrease, change, difference).
- Type the two numbers the mode asks for.
- Read the result, then use the breakdown line to see the arithmetic.
- For money, sanity-check the direction: an increase result must be bigger than the start, a decrease smaller.
What the inputs mean
| Input | What it is | Typical values |
|---|---|---|
| Percent | The rate being applied | 5–30% for tips/tax; any value works |
| Part / whole | The piece and the total it belongs to | Part must be ≤ whole for a share |
| From / to | Start and end values for change | Prices, scores, weights, counts |
Another worked example
Three everyday answers from one tool: 18% of 240 is 43.2 (a tax or tip line); 45 out of 180 is exactly 25% (a test score); and a price moving from $120 to $150 is a +25% change — note the return trip, $150 down to $120, is −20%, because percent change always divides by where you started.
Frequently asked questions
What is the difference between percent change and percent difference?
Percent change is directional: it measures growth or decline from an old value to a new one, so swapping the numbers changes the answer. Percent difference treats both numbers equally by dividing by their average, so the order does not matter.
How do I find what percent one number is of another?
Divide the part by the whole and multiply by 100. For example, 30 out of 150 is 30 ÷ 150 × 100 = 20%. Use the "Number as %" mode above.
How do I increase a number by a percentage?
Multiply the number by (1 + p ÷ 100). Increasing 150 by 20% gives 150 × 1.2 = 180. The "% increase" mode shows both the new value and the amount added.
Can a percentage be more than 100?
Yes. A percent is just a ratio to 100 — 250% of 40 is 100, and a price that triples has increased by 200%. Percentages below 0 appear when a change is negative.
🏷️ Shopping math, handled
Pair percentages with the Discount Calculator to see the final price with tax included.
Why is a 25% increase not undone by a 25% decrease?
Because the base changes. $100 up 25% is $125; $125 down 25% is $93.75. Percent change is always relative to the starting value of that step, which is why this tool asks for 'from' and 'to' explicitly.
What is the difference between percent change and percentage difference?
Change has a direction and a start (old → new). Difference compares two peers symmetrically, dividing by their average — the right choice when neither number is 'before' or 'after', like comparing two products' prices.