Percentage Calculator
Four quick percentage calculators plus a tip & discount helper — every answer updates as you type.
How it works
-
Pick the line that matches your question — X% of a number, what percent, percent change, or reverse percentage.
-
Type your two numbers into that line.
-
Read the answer sentence right below the inputs — it updates live.
-
Use the tip & discount block to add or subtract a percentage from any amount.
Frequently asked questions
How is percent change calculated?
Percent change = (new − old) ÷ |old| × 100. Going from 80 to 100 is a 25% increase; going from 100 to 80 is a 20% decrease — the two directions are not symmetric, which is why the wording matters.
What is a reverse percentage?
It answers "Y is X% of what number?" — the whole is Y ÷ (X ÷ 100). For example, if 30 is 20% of something, the something is 30 ÷ 0.20 = 150. Handy for working back from a deposit, a discount, or a partial score.
How does the tip & discount block work?
Enter an amount and a percentage. We show the percentage amount itself, the total with it added (a tip or tax), and the total with it subtracted (a discount) — all three at once, rounded to two decimals.
Are my numbers sent to a server?
No. All calculations run entirely in your browser — nothing is uploaded or stored. Close the page and the numbers are gone.
Related tools
Statistics Calculator
Mean, median, mode, standard deviation, quartiles, and outliers — with a histogram and box plot drawn from your data.
Scientific Calculator
Type full expressions with sin, cos, log, √, π and more — evaluated instantly, with history and an ans variable.
Unit Converter
Instant conversions across length, weight, temperature, and more — as you type.
GPA Calculator
Term and cumulative GPA, weighted by credit hours — on 4.0 and 5.0 grading scales.