Fast browser calculator tools

Quick Percentage Calculator

Fast, private percentage math for shopping, finance, spreadsheets, and everyday work.

Ready in browser
No install
Fast, private, and responsive on desktop and mobile.

Calculators

Quick Percentage Calculator

Fast, private percentage math for shopping, finance, spreadsheets, and everyday work.

Percent of a number Increase / decrease Reverse percentage Discount calculator
Common formula Value = part ÷ rate
Fast output Result + explanation
Built to be Simple, direct, mobile-friendly

Mode 1

Percentage of a Number

What is X% of Y?

%

Formula: result = percentage × number ÷ 100

Result
--
Enter a percentage and a number to see the formula explanation.
Example: 20% of 150 = 30

Mode 2

Percentage Increase / Decrease

From A to B

Formula: ((new - original) ÷ original) × 100

Change
--
No change
Compare two values to see the exact percentage change.
Example: 80 → 100 = 25% increase

Mode 3

Reverse Percentage Calculator

X is Y% of what?

%

Formula: original = partial × 100 ÷ percentage

Original value
--
Use a partial value and percentage to recover the full amount.
Example: 80 is 40% of what = 200

Mode 4

Discount Calculator

X% off Y

%

Formula: final = price - (price × discount ÷ 100)

Savings
--
Final price
--
Enter a price and discount to see the savings and sale price.
Example: 30% off 120 = 84

Calculators

Age Calculator

Calculate an exact age from a date of birth and an optional reference date with a polished, browser-only workflow.

Date of birth Optional reference date Live results Exact time units
Inputs DOB + reference date
Outputs Years through seconds
Built for Fast, private, accurate age checks

Age Calculator

Exact Age From Date of Birth

Enter a birth date and compare it against today or another date.

Leave blank to use today's date.
Age summary
--
Select a date of birth to calculate an exact age.
Years
--
Months
--
Weeks
--
Days
--
Hours
--
Minutes
--
Seconds
--
Example: someone born on 2000-01-01 will show the exact elapsed years, months, weeks, days, hours, minutes, and seconds.